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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
#nullable disable
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.IO;
using System.Linq;
using System.Text;
using Microsoft.CodeAnalysis.CSharp.Symbols;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
using Microsoft.CodeAnalysis.Emit;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Roslyn.Utilities;
using Xunit;
namespace Microsoft.CodeAnalysis.CSharp.UnitTests
{
public class LambdaTests : SemanticModelTestBase
{
[Fact, WorkItem(37456, "https://github.com/dotnet/roslyn/issues/37456")]
public void Verify37456()
{
var comp = CreateCompilation(@"
using System;
using System.Collections.Generic;
using System.Linq;
public static partial class EnumerableEx
{
public static void Join1<TA, TKey, T>(this IEnumerable<TA> a, Func<TA, TKey> aKey, Func<TA, T> aSel, Func<TA, TA, T> sel)
{
KeyValuePair<TK, TV> Pair<TK, TV>(TK k, TV v) => new KeyValuePair<TK, TV>(k, v);
_ = a.GroupJoin(a, aKey, aKey, (f, ss) => Pair(f, ss.Select(s => Pair(true, s)))); // simplified repro
}
public static IEnumerable<T> Join2<TA, TB, TKey, T>(this IEnumerable<TA> a, IEnumerable<TB> b, Func<TA, TKey> aKey, Func<TB, TKey> bKey, Func<TA, T> aSel, Func<TA, TB, T> sel, IEqualityComparer<TKey> comp)
{
KeyValuePair<TK, TV> Pair<TK, TV>(TK k, TV v) => new KeyValuePair<TK, TV>(k, v);
return
from j in a.GroupJoin(b, aKey, bKey, (f, ss) => Pair(f, from s in ss select Pair(true, s)), comp)
from s in j.Value.DefaultIfEmpty()
select s.Key ? sel(j.Key, s.Value) : aSel(j.Key);
}
}");
comp.VerifyDiagnostics();
CompileAndVerify(comp);
// emitting should not hang
}
[Fact, WorkItem(608181, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/608181")]
public void BadInvocationInLambda()
{
var src = @"
using System;
using System.Linq.Expressions;
class C
{
Expression<Action<dynamic>> e = x => new object[](x);
}";
var comp = CreateCompilationWithMscorlib40AndSystemCore(src);
comp.VerifyDiagnostics(
// (7,52): error CS1586: Array creation must have array size or array initializer
// Expression<Action<dynamic>> e = x => new object[](x);
Diagnostic(ErrorCode.ERR_MissingArraySize, "[]").WithLocation(7, 52)
);
}
[Fact]
public void TestLambdaErrors01()
{
var comp = CreateCompilationWithMscorlib40AndSystemCore(@"
using System;
using System.Linq.Expressions;
namespace System.Linq.Expressions
{
public class Expression<T> {}
}
class C
{
delegate void D1(ref int x, out int y, int z);
delegate void D2(out int x);
void M()
{
int q1 = ()=>1;
int q2 = delegate { return 1; };
Func<int> q3 = x3=>1;
Func<int, int> q4 = (System.Itn23 x4)=>1; // type mismatch error should be suppressed on error type
Func<double> q5 = (System.Duobel x5)=>1; // but arity error should not be suppressed on error type
D1 q6 = (double x6, ref int y6, ref int z6)=>1;
// COMPATIBILITY: The C# 4 compiler produces two errors:
//
// error CS1676: Parameter 2 must be declared with the 'out' keyword
// error CS1688: Cannot convert anonymous method block without a parameter list
// to delegate type 'D1' because it has one or more out parameters
//
// This seems redundant (because there is no 'parameter 2' in the source code)
// I propose that we eliminate the first error.
D1 q7 = delegate {};
Frob q8 = ()=>{};
D2 q9 = x9=>{};
D1 q10 = (x10,y10,z10)=>{};
// COMPATIBILITY: The C# 4 compiler produces two errors:
//
// error CS0127: Since 'System.Action' returns void, a return keyword must
// not be followed by an object expression
//
// error CS1662: Cannot convert lambda expression to delegate type 'System.Action'
// because some of the return types in the block are not implicitly convertible to
// the delegate return type
//
// The problem is adequately characterized by the first message; I propose we
// eliminate the second, which seems both redundant and wrong.
Action q11 = ()=>{ return 1; };
Action q12 = ()=>1;
Func<int> q13 = ()=>{ if (false) return 1; };
Func<int> q14 = ()=>123.456;
// Note that the type error is still an error even if the offending
// return is unreachable.
Func<double> q15 = ()=>{if (false) return 1m; else return 0; };
// In the native compiler these errors were caught at parse time. In Roslyn, these are now semantic
// analysis errors. See changeset 1674 for details.
Action<int[]> q16 = delegate (params int[] p) { };
Action<string[]> q17 = (params string[] s)=>{};
Action<int, double[]> q18 = (int x, params double[] s)=>{};
object q19 = new Action( (int x)=>{} );
Expression<int> ex1 = ()=>1;
}
}");
comp.VerifyDiagnostics(
// (16,20): error CS1660: Cannot convert lambda expression to type 'int' because it is not a delegate type
// int q1 = ()=>1;
Diagnostic(ErrorCode.ERR_AnonMethToNonDel, "=>").WithArguments("lambda expression", "int").WithLocation(16, 20),
// (17,18): error CS1660: Cannot convert anonymous method to type 'int' because it is not a delegate type
// int q2 = delegate { return 1; };
Diagnostic(ErrorCode.ERR_AnonMethToNonDel, "delegate").WithArguments("anonymous method", "int").WithLocation(17, 18),
// (18,26): error CS1593: Delegate 'Func<int>' does not take 1 arguments
// Func<int> q3 = x3=>1;
Diagnostic(ErrorCode.ERR_BadDelArgCount, "=>").WithArguments("System.Func<int>", "1").WithLocation(18, 26),
// (19,37): error CS0234: The type or namespace name 'Itn23' does not exist in the namespace 'System' (are you missing an assembly reference?)
// Func<int, int> q4 = (System.Itn23 x4)=>1; // type mismatch error should be suppressed on error type
Diagnostic(ErrorCode.ERR_DottedTypeNameNotFoundInNS, "Itn23").WithArguments("Itn23", "System").WithLocation(19, 37),
// (20,35): error CS0234: The type or namespace name 'Duobel' does not exist in the namespace 'System' (are you missing an assembly reference?)
// Func<double> q5 = (System.Duobel x5)=>1; // but arity error should not be suppressed on error type
Diagnostic(ErrorCode.ERR_DottedTypeNameNotFoundInNS, "Duobel").WithArguments("Duobel", "System").WithLocation(20, 35),
// (20,45): error CS1593: Delegate 'Func<double>' does not take 1 arguments
// Func<double> q5 = (System.Duobel x5)=>1; // but arity error should not be suppressed on error type
Diagnostic(ErrorCode.ERR_BadDelArgCount, "=>").WithArguments("System.Func<double>", "1").WithLocation(20, 45),
// (21,52): error CS1661: Cannot convert lambda expression to type 'C.D1' because the parameter types do not match the delegate parameter types
// D1 q6 = (double x6, ref int y6, ref int z6)=>1;
Diagnostic(ErrorCode.ERR_CantConvAnonMethParams, "=>").WithArguments("lambda expression", "C.D1").WithLocation(21, 52),
// (21,25): error CS1678: Parameter 1 is declared as type 'double' but should be 'ref int'
// D1 q6 = (double x6, ref int y6, ref int z6)=>1;
Diagnostic(ErrorCode.ERR_BadParamType, "x6").WithArguments("1", "", "double", "ref ", "int").WithLocation(21, 25),
// (21,37): error CS1676: Parameter 2 must be declared with the 'out' keyword
// D1 q6 = (double x6, ref int y6, ref int z6)=>1;
Diagnostic(ErrorCode.ERR_BadParamRef, "y6").WithArguments("2", "out").WithLocation(21, 37),
// (21,49): error CS1677: Parameter 3 should not be declared with the 'ref' keyword
// D1 q6 = (double x6, ref int y6, ref int z6)=>1;
Diagnostic(ErrorCode.ERR_BadParamExtraRef, "z6").WithArguments("3", "ref").WithLocation(21, 49),
// (32,17): error CS1688: Cannot convert anonymous method block without a parameter list to delegate type 'C.D1' because it has one or more out parameters
// D1 q7 = delegate {};
Diagnostic(ErrorCode.ERR_CantConvAnonMethNoParams, "delegate").WithArguments("C.D1").WithLocation(32, 17),
// (34,9): error CS0246: The type or namespace name 'Frob' could not be found (are you missing a using directive or an assembly reference?)
// Frob q8 = ()=>{};
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Frob").WithArguments("Frob").WithLocation(34, 9),
// (36,17): error CS1676: Parameter 1 must be declared with the 'out' keyword
// D2 q9 = x9=>{};
Diagnostic(ErrorCode.ERR_BadParamRef, "x9").WithArguments("1", "out").WithLocation(36, 17),
// (38,19): error CS1676: Parameter 1 must be declared with the 'ref' keyword
// D1 q10 = (x10,y10,z10)=>{};
Diagnostic(ErrorCode.ERR_BadParamRef, "x10").WithArguments("1", "ref").WithLocation(38, 19),
// (38,23): error CS1676: Parameter 2 must be declared with the 'out' keyword
// D1 q10 = (x10,y10,z10)=>{};
Diagnostic(ErrorCode.ERR_BadParamRef, "y10").WithArguments("2", "out").WithLocation(38, 23),
// (52,28): error CS8030: Anonymous function converted to a void returning delegate cannot return a value
// Action q11 = ()=>{ return 1; };
Diagnostic(ErrorCode.ERR_RetNoObjectRequiredLambda, "return").WithLocation(52, 28),
// (54,26): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
// Action q12 = ()=>1;
Diagnostic(ErrorCode.ERR_IllegalStatement, "1").WithLocation(54, 26),
// (56,42): warning CS0162: Unreachable code detected
// Func<int> q13 = ()=>{ if (false) return 1; };
Diagnostic(ErrorCode.WRN_UnreachableCode, "return").WithLocation(56, 42),
// (56,27): error CS1643: Not all code paths return a value in lambda expression of type 'Func<int>'
// Func<int> q13 = ()=>{ if (false) return 1; };
Diagnostic(ErrorCode.ERR_AnonymousReturnExpected, "=>").WithArguments("lambda expression", "System.Func<int>").WithLocation(56, 27),
// (58,29): error CS0266: Cannot implicitly convert type 'double' to 'int'. An explicit conversion exists (are you missing a cast?)
// Func<int> q14 = ()=>123.456;
Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "123.456").WithArguments("double", "int").WithLocation(58, 29),
// (58,29): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<int> q14 = ()=>123.456;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "123.456").WithArguments("lambda expression").WithLocation(58, 29),
// (62,51): error CS0266: Cannot implicitly convert type 'decimal' to 'double'. An explicit conversion exists (are you missing a cast?)
// Func<double> q15 = ()=>{if (false) return 1m; else return 0; };
Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "1m").WithArguments("decimal", "double").WithLocation(62, 51),
// (62,51): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<double> q15 = ()=>{if (false) return 1m; else return 0; };
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "1m").WithArguments("lambda expression").WithLocation(62, 51),
// (62,44): warning CS0162: Unreachable code detected
// Func<double> q15 = ()=>{if (false) return 1m; else return 0; };
Diagnostic(ErrorCode.WRN_UnreachableCode, "return").WithLocation(62, 44),
// (66,39): error CS1670: params is not valid in this context
// Action<int[]> q16 = delegate (params int[] p) { };
Diagnostic(ErrorCode.ERR_IllegalParams, "params").WithLocation(66, 39),
// (67,49): warning CS9100: Parameter 1 has params modifier in lambda but not in target delegate type.
// Action<string[]> q17 = (params string[] s)=>{};
Diagnostic(ErrorCode.WRN_ParamsArrayInLambdaOnly, "s").WithArguments("1").WithLocation(67, 49),
// (68,61): warning CS9100: Parameter 2 has params modifier in lambda but not in target delegate type.
// Action<int, double[]> q18 = (int x, params double[] s)=>{};
Diagnostic(ErrorCode.WRN_ParamsArrayInLambdaOnly, "s").WithArguments("2").WithLocation(68, 61),
// (70,41): error CS1593: Delegate 'Action' does not take 1 arguments
// object q19 = new Action( (int x)=>{} );
Diagnostic(ErrorCode.ERR_BadDelArgCount, "=>").WithArguments("System.Action", "1").WithLocation(70, 41),
// (72,9): warning CS0436: The type 'Expression<T>' in '' conflicts with the imported type 'Expression<TDelegate>' in 'System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. Using the type defined in ''.
// Expression<int> ex1 = ()=>1;
Diagnostic(ErrorCode.WRN_SameFullNameThisAggAgg, "Expression<int>").WithArguments("", "System.Linq.Expressions.Expression<T>", "System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "System.Linq.Expressions.Expression<TDelegate>").WithLocation(72, 9),
// (72,33): error CS0835: Cannot convert lambda to an expression tree whose type argument 'int' is not a delegate type
// Expression<int> ex1 = ()=>1;
Diagnostic(ErrorCode.ERR_ExpressionTreeMustHaveDelegate, "=>").WithArguments("int").WithLocation(72, 33));
}
[Fact] // 5368
public void TestLambdaErrors02()
{
string code = @"
class C
{
void M()
{
System.Func<int, int> del = x => x + 1;
}
}";
var compilation = CreateCompilation(code);
compilation.VerifyDiagnostics(); // no errors expected
}
[WorkItem(539538, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/539538")]
[Fact]
public void TestLambdaErrors03()
{
string source = @"
using System;
interface I : IComparable<IComparable<I>> { }
class C
{
static void Goo(Func<IComparable<I>> x) { }
static void Goo(Func<I> x) {}
static void M()
{
Goo(() => null);
}
}
";
CreateCompilation(source).VerifyDiagnostics(
// (12,9): error CS0121: The call is ambiguous between the following methods or properties: 'C.Goo(Func<IComparable<I>>)' and 'C.Goo(Func<I>)'
// Goo(() => null);
Diagnostic(ErrorCode.ERR_AmbigCall, "Goo").WithArguments("C.Goo(System.Func<System.IComparable<I>>)", "C.Goo(System.Func<I>)").WithLocation(12, 9));
}
[WorkItem(18645, "https://github.com/dotnet/roslyn/issues/18645")]
[Fact]
public void LambdaExpressionTreesErrors()
{
string source = @"
using System;
using System.Linq.Expressions;
class C
{
void M()
{
Expression<Func<int,int>> ex1 = () => 1;
Expression<Func<int,int>> ex2 = (double d) => 1;
}
}
";
CreateCompilation(source).VerifyDiagnostics(
// (9,44): error CS1593: Delegate 'Func<int, int>' does not take 0 arguments
// Expression<Func<int,int>> ex1 = () => 1;
Diagnostic(ErrorCode.ERR_BadDelArgCount, "=>").WithArguments("System.Func<int, int>", "0").WithLocation(9, 44),
// (10,49): error CS1678: Parameter 1 is declared as type 'double' but should be 'int'
// Expression<Func<int,int>> ex2 = (double d) => 1;
Diagnostic(ErrorCode.ERR_BadParamType, "d").WithArguments("1", "", "double", "", "int").WithLocation(10, 49),
// (10,52): error CS1661: Cannot convert lambda expression to type 'Expression<Func<int, int>>' because the parameter types do not match the delegate parameter types
// Expression<Func<int,int>> ex2 = (double d) => 1;
Diagnostic(ErrorCode.ERR_CantConvAnonMethParams, "=>").WithArguments("lambda expression", "System.Linq.Expressions.Expression<System.Func<int, int>>").WithLocation(10, 52));
}
[WorkItem(539976, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/539976")]
[Fact]
public void LambdaArgumentToOverloadedDelegate()
{
var text = @"class W
{
delegate T Func<A0, T>(A0 a0);
static int F(Func<short, int> f) { return 0; }
static int F(Func<short, double> f) { return 1; }
static int Main()
{
return F(c => c);
}
}
";
var comp = CreateCompilation(Parse(text));
comp.VerifyDiagnostics();
}
[WorkItem(528044, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/528044")]
[Fact]
public void MissingReferenceInOverloadResolution()
{
var text1 = @"
using System;
public static class A
{
public static void Goo(Func<B, object> func) { }
public static void Goo(Func<C, object> func) { }
}
public class B
{
public Uri GetUrl()
{
return null;
}
}
public class C
{
public string GetUrl()
{
return null;
}
}";
var comp1 = CreateCompilationWithMscorlib40(
new[] { Parse(text1) },
new[] { NetFramework.System });
var text2 = @"
class Program
{
static void Main()
{
A.Goo(x => x.GetUrl());
}
}
";
var comp2 = CreateCompilationWithMscorlib40(
new[] { Parse(text2) },
new[] { new CSharpCompilationReference(comp1) });
Assert.Equal(0, comp2.GetDiagnostics().Count());
}
[WorkItem(528047, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/528047")]
[Fact()]
public void OverloadResolutionWithEmbeddedInteropType()
{
var text1 = @"
using System;
using System.Collections.Generic;
using stdole;
public static class A
{
public static void Goo(Func<X> func)
{
System.Console.WriteLine(""X"");
}
public static void Goo(Func<Y> func)
{
System.Console.WriteLine(""Y"");
}
}
public delegate void X(List<IDispatch> addin);
public delegate void Y(List<string> addin);
";
var comp1 = CreateCompilation(
Parse(text1),
targetFramework: TargetFramework.NetFramework,
references: [TestReferences.SymbolsTests.NoPia.StdOleNetFramework.WithEmbedInteropTypes(true)],
options: TestOptions.ReleaseDll);
var text2 = @"
public class Program
{
public static void Main()
{
A.Goo(() => delegate { });
}
}
";
var comp2 = CreateCompilation(
Parse(text2),
targetFramework: TargetFramework.NetFramework,
references:
[
new CSharpCompilationReference(comp1),
TestReferences.SymbolsTests.NoPia.StdOleNetFramework.WithEmbedInteropTypes(true)
],
options: TestOptions.ReleaseExe);
CompileAndVerify(comp2, expectedOutput: "Y").Diagnostics.Verify();
var comp3 = CreateCompilation(
Parse(text2),
targetFramework: TargetFramework.NetFramework,
references:
[
comp1.EmitToImageReference(),
TestReferences.SymbolsTests.NoPia.StdOleNetFramework.WithEmbedInteropTypes(true)
],
options: TestOptions.ReleaseExe);
CompileAndVerify(comp3, expectedOutput: "Y").Diagnostics.Verify();
}
[WorkItem(6358, "DevDiv_Projects/Roslyn")]
[Fact]
public void InvalidExpressionInvolveLambdaOperator()
{
var text1 = @"
class C
{
static void X()
{
int x=0; int y=0;
if(x-=>*y) // CS1525
return;
return;
}
}
";
var comp = CreateCompilation(Parse(text1));
var errs = comp.GetDiagnostics();
Assert.True(0 < errs.Count(), "Diagnostics not empty");
Assert.True(0 < errs.Where(e => e.Code == 1525).Select(e => e).Count(), "Diagnostics contains CS1525");
}
[WorkItem(540219, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/540219")]
[Fact]
public void OverloadResolutionWithStaticType()
{
var vbSource = @"
Imports System
Namespace Microsoft.VisualBasic.CompilerServices
<System.AttributeUsage(System.AttributeTargets.Class, Inherited:=False, AllowMultiple:=False)>
Public NotInheritable Class StandardModuleAttribute
Inherits System.Attribute
Public Sub New()
MyBase.New()
End Sub
End Class
End Namespace
Public Module M
Sub Goo(x as Action(Of String))
End Sub
Sub Goo(x as Action(Of GC))
End Sub
End Module
";
var vbProject = VisualBasic.VisualBasicCompilation.Create(
"VBProject",
references: new[] { MscorlibRef },
syntaxTrees: new[] { VisualBasic.VisualBasicSyntaxTree.ParseText(vbSource) });
var csSource = @"
class Program
{
static void Main()
{
M.Goo(x => { });
}
}
";
var metadataStream = new MemoryStream();
var emitResult = vbProject.Emit(metadataStream, options: new EmitOptions(metadataOnly: true));
Assert.True(emitResult.Success);
var csProject = CreateCompilation(
Parse(csSource),
new[] { MetadataReference.CreateFromImage(metadataStream.ToImmutable()) });
Assert.Equal(0, csProject.GetDiagnostics().Count());
}
[Fact]
public void OverloadResolutionWithStaticTypeError()
{
var vbSource = @"
Imports System
Namespace Microsoft.VisualBasic.CompilerServices
<System.AttributeUsage(System.AttributeTargets.Class, Inherited:=False, AllowMultiple:=False)>
Public NotInheritable Class StandardModuleAttribute
Inherits System.Attribute
Public Sub New()
MyBase.New()
End Sub
End Class
End Namespace
Public Module M
Public Dim F As Action(Of GC)
End Module
";
var vbProject = VisualBasic.VisualBasicCompilation.Create(
"VBProject",
references: new[] { MscorlibRef },
syntaxTrees: new[] { VisualBasic.VisualBasicSyntaxTree.ParseText(vbSource) });
var csSource = @"
class Program
{
static void Main()
{
M.F = x=>{};
}
}
";
var vbMetadata = vbProject.EmitToArray(options: new EmitOptions(metadataOnly: true));
var csProject = CreateCompilation(Parse(csSource), new[] { MetadataReference.CreateFromImage(vbMetadata) });
csProject.VerifyDiagnostics(
// (6,15): error CS0721: 'GC': static types cannot be used as parameters
// M.F = x=>{};
Diagnostic(ErrorCode.ERR_ParameterIsStaticClass, "x").WithArguments("System.GC").WithLocation(6, 15));
}
[Fact]
public void StaticTypeLambdaParameter()
{
var source = """
static class StaticClass {}
class Program
{
public void M()
{
var lam = (StaticClass sc) => sc;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,20): error CS0721: 'StaticClass': static types cannot be used as parameters
// var lam = (StaticClass sc) => sc;
Diagnostic(ErrorCode.ERR_ParameterIsStaticClass, "StaticClass").WithArguments("StaticClass").WithLocation(7, 20));
}
[Fact]
public void ScopedNonRefValueRefStructLambdaParam()
{
var source = """
public class Program
{
public void M()
{
var lam = (scoped int n) => n;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,20): error CS9048: The 'scoped' modifier can be used for refs and ref struct values only.
// var lam = (scoped int n) => n;
Diagnostic(ErrorCode.ERR_ScopedRefAndRefStructOnly, "scoped int n").WithLocation(5, 20));
}
[WorkItem(62960, "https://github.com/dotnet/roslyn/issues/62960")]
[Fact]
public void ReferenceToRestrictedTypeLambdaParameter()
{
var source = """
using System;
public class Program
{
public void M()
{
var lam = (ref TypedReference r) => {};
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (6,20): error CS1601: Cannot make reference to variable of type 'TypedReference'
// var lam = (ref TypedReference r) => {};
Diagnostic(ErrorCode.ERR_MethodArgCantBeRefAny, "ref TypedReference r").WithArguments("System.TypedReference").WithLocation(6, 20));
}
[WorkItem(540251, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/540251")]
[Fact]
public void AttributesCannotBeUsedInAnonymousMethods()
{
var csSource = @"
using System;
class Program
{
static void Main()
{
const string message = ""The parameter is obsolete"";
Action<int> a = delegate ([ObsoleteAttribute(message)] int x) { };
}
}
";
var csProject = CreateCompilation(csSource);
csProject.VerifyEmitDiagnostics(
// (8,22): warning CS0219: The variable 'message' is assigned but its value is never used
// const string message = "The parameter is obsolete";
Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "message").WithArguments("message").WithLocation(8, 22),
// (9,35): error CS7014: Attributes are not valid in this context.
// Action<int> a = delegate ([ObsoleteAttribute(message)] int x) { };
Diagnostic(ErrorCode.ERR_AttributesNotAllowed, "[ObsoleteAttribute(message)]").WithLocation(9, 35));
}
[WorkItem(540263, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/540263")]
[Fact]
public void ErrorsInUnboundLambdas()
{
var csSource = @"using System;
class Program
{
static void Main()
{
((Func<int>)delegate { return """"; })();
((Func<int>)delegate { })();
((Func<int>)delegate { 1 / 0; })();
}
}
";
CreateCompilation(csSource).VerifyDiagnostics(
// (7,39): error CS0029: Cannot implicitly convert type 'string' to 'int'
// ((Func<int>)delegate { return ""; })();
Diagnostic(ErrorCode.ERR_NoImplicitConv, @"""""").WithArguments("string", "int").WithLocation(7, 39),
// (7,39): error CS1662: Cannot convert anonymous method to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// ((Func<int>)delegate { return ""; })();
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, @"""""").WithArguments("anonymous method").WithLocation(7, 39),
// (8,21): error CS1643: Not all code paths return a value in anonymous method of type 'Func<int>'
// ((Func<int>)delegate { })();
Diagnostic(ErrorCode.ERR_AnonymousReturnExpected, "delegate").WithArguments("anonymous method", "System.Func<int>").WithLocation(8, 21),
// (9,32): error CS0020: Division by constant zero
// ((Func<int>)delegate { 1 / 0; })();
Diagnostic(ErrorCode.ERR_IntDivByZero, "1 / 0").WithLocation(9, 32),
// (9,32): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
// ((Func<int>)delegate { 1 / 0; })();
Diagnostic(ErrorCode.ERR_IllegalStatement, "1 / 0").WithLocation(9, 32),
// (9,21): error CS1643: Not all code paths return a value in anonymous method of type 'Func<int>'
// ((Func<int>)delegate { 1 / 0; })();
Diagnostic(ErrorCode.ERR_AnonymousReturnExpected, "delegate").WithArguments("anonymous method", "System.Func<int>").WithLocation(9, 21)
);
}
[WorkItem(540181, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/540181")]
[Fact]
public void ErrorInLambdaArgumentList()
{
var csSource = @"using System;
class Program
{
public Program(string x) : this(() => x) { }
static void Main(string[] args)
{
((Action<string>)(f => Console.WriteLine(f)))(nulF);
}
}";
CreateCompilation(csSource).VerifyDiagnostics(
// (5,40): error CS1660: Cannot convert lambda expression to type 'string' because it is not a delegate type
// public Program(string x) : this(() => x) { }
Diagnostic(ErrorCode.ERR_AnonMethToNonDel, "=>").WithArguments("lambda expression", "string").WithLocation(5, 40),
// (8,55): error CS0103: The name 'nulF' does not exist in the current context
// ((Action<string>)(f => Console.WriteLine(f)))(nulF);
Diagnostic(ErrorCode.ERR_NameNotInContext, "nulF").WithArguments("nulF").WithLocation(8, 55));
}
[WorkItem(541725, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/541725")]
[Fact]
public void DelegateCreationIsNotStatement()
{
var csSource = @"
delegate void D();
class Program
{
public static void Main(string[] args)
{
D d = () => new D(() => { });
new D(()=>{});
}
}";
// Though it is legal to have an object-creation-expression, because it might be useful
// for its side effects, a delegate-creation-expression is not allowed as a
// statement expression.
CreateCompilation(csSource).VerifyDiagnostics(
// (7,21): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
// D d = () => new D(() => { });
Diagnostic(ErrorCode.ERR_IllegalStatement, "new D(() => { })"),
// (8,9): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
// new D(()=>{});
Diagnostic(ErrorCode.ERR_IllegalStatement, "new D(()=>{})"));
}
[WorkItem(542336, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/542336")]
[Fact]
public void ThisInStaticContext()
{
var csSource = @"
delegate void D();
class Program
{
public static void Main(string[] args)
{
D d = () => {
object o = this;
};
}
}";
CreateCompilation(csSource).VerifyDiagnostics(
// (8,24): error CS0026: Keyword 'this' is not valid in a static property, static method, or static field initializer
// object o = this;
Diagnostic(ErrorCode.ERR_ThisInStaticMeth, "this")
);
}
[WorkItem(542431, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/542431")]
[Fact]
public void LambdaHasMoreParametersThanDelegate()
{
var csSource = @"
class C
{
static void Main()
{
System.Func<int> f = new System.Func<int>(r => 0);
}
}";
CreateCompilation(csSource).VerifyDiagnostics(
// (6,53): error CS1593: Delegate 'Func<int>' does not take 1 arguments
// System.Func<int> f = new System.Func<int>(r => 0);
Diagnostic(ErrorCode.ERR_BadDelArgCount, "=>").WithArguments("System.Func<int>", "1").WithLocation(6, 53));
}
[Fact, WorkItem(529054, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/529054")]
public void LambdaInDynamicCall()
{
var source = @"
public class Program
{
static void Main()
{
dynamic b = new string[] { ""AA"" };
bool exists = System.Array.Exists(b, o => o != ""BB"");
}
}";
CreateCompilation(source).VerifyDiagnostics(
// (7,46): error CS1977: Cannot use a lambda expression as an argument to a dynamically dispatched operation without first casting it to a delegate or expression tree type.
// bool exists = System.Array.Exists(b, o => o != "BB");
Diagnostic(ErrorCode.ERR_BadDynamicMethodArgLambda, @"o => o != ""BB""")
);
}
[Fact, WorkItem(529389, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/529389")]
public void ParenthesizedLambdaInCastExpression()
{
var source = @"
using System;
using System.Collections.Generic;
class Program
{
static void Main()
{
int x = 1;
byte y = (byte) (x + x);
Func<int> f1 = (() => { return 1; });
Func<int> f2 = (Func<int>) (() => { return 2; });
}
}
";
var tree = SyntaxFactory.ParseSyntaxTree(source);
var comp = CreateCompilation(tree);
var model = comp.GetSemanticModel(tree);
ExpressionSyntax expr = tree.GetCompilationUnitRoot().DescendantNodes().OfType<BinaryExpressionSyntax>().
Where(e => e.Kind() == SyntaxKind.AddExpression).Single();
var tinfo = model.GetTypeInfo(expr);
var conv = model.GetConversion(expr);
// Not byte
Assert.Equal("int", tinfo.Type.ToDisplayString());
var exprs = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ParenthesizedLambdaExpressionSyntax>();
expr = exprs.First();
tinfo = model.GetTypeInfo(expr);
conv = model.GetConversion(expr);
Assert.True(conv.IsAnonymousFunction, "LambdaConversion");
Assert.Null(tinfo.Type);
var sym = model.GetSymbolInfo(expr).Symbol;
Assert.NotNull(sym);
Assert.Equal(SymbolKind.Method, sym.Kind);
Assert.Equal(MethodKind.AnonymousFunction, (sym as IMethodSymbol).MethodKind);
expr = exprs.Last();
tinfo = model.GetTypeInfo(expr);
conv = model.GetConversion(expr);
Assert.True(conv.IsAnonymousFunction, "LambdaConversion");
Assert.Null(tinfo.Type);
sym = model.GetSymbolInfo(expr).Symbol;
Assert.NotNull(sym);
Assert.Equal(SymbolKind.Method, sym.Kind);
Assert.Equal(MethodKind.AnonymousFunction, (sym as IMethodSymbol).MethodKind);
}
[WorkItem(544594, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544594")]
[Fact]
public void LambdaInEnumMemberDecl()
{
var csSource = @"
public class TestClass
{
public enum Test { aa = ((System.Func<int>)(() => 1))() }
Test MyTest = Test.aa;
public static void Main()
{
}
}
";
CreateCompilation(csSource).VerifyDiagnostics(
// (4,29): error CS0133: The expression being assigned to 'TestClass.Test.aa' must be constant
Diagnostic(ErrorCode.ERR_NotConstantExpression, "((System.Func<int>)(() => 1))()").WithArguments("TestClass.Test.aa"),
// (5,10): warning CS0414: The field 'TestClass.MyTest' is assigned but its value is never used
Diagnostic(ErrorCode.WRN_UnreferencedFieldAssg, "MyTest").WithArguments("TestClass.MyTest"));
}
[WorkItem(544932, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544932")]
[Fact]
public void AnonymousLambdaInEnumSubtraction()
{
string source = @"
class Test
{
enum E1 : byte
{
A = byte.MinValue,
C = 1
}
static void Main()
{
int j = ((System.Func<Test.E1>)(() => E1.A))() - E1.C;
System.Console.WriteLine(j);
}
}
";
string expectedOutput = @"255";
CompileAndVerify(new[] { source }, expectedOutput: expectedOutput);
}
[WorkItem(545156, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/545156")]
[Fact]
public void SpeculativelyBindOverloadResolution()
{
string source = @"
using System;
using System.Collections;
using System.Collections.Generic;
class Program
{
static void Main()
{
Goo(() => () => { var x = (IEnumerable<int>)null; return x; });
}
static void Goo(Func<Func<IEnumerable>> x) { }
static void Goo(Func<Func<IFormattable>> x) { }
}
";
var compilation = CreateCompilation(source);
var tree = compilation.SyntaxTrees.Single();
var model = compilation.GetSemanticModel(tree);
var invocation = tree.GetCompilationUnitRoot().DescendantNodes().OfType<InvocationExpressionSyntax>().Single();
// Used to throw a NRE because of the ExpressionSyntax's null SyntaxTree.
model.GetSpeculativeSymbolInfo(
invocation.SpanStart,
SyntaxFactory.ParseExpression("Goo(() => () => { var x = null; return x; })"), // cast removed
SpeculativeBindingOption.BindAsExpression);
}
[WorkItem(545343, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/545343")]
[Fact]
public void LambdaUsingFieldInConstructor()
{
string source = @"
using System;
public class Derived
{
int field = 1;
Derived()
{
int local = 2;
// A lambda that captures a local and refers to an instance field.
Action a = () => Console.WriteLine(""Local = {0}, Field = {1}"", local, field);
// NullReferenceException if the ""this"" field of the display class hasn't been set.
a();
}
public static void Main()
{
Derived d = new Derived();
}
}";
CompileAndVerify(source, expectedOutput: "Local = 2, Field = 1");
}
[WorkItem(642222, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/642222")]
[Fact]
public void SpeculativelyBindOverloadResolutionAndInferenceWithError()
{
string source = @"
using System;using System.Linq.Expressions;
namespace IntellisenseBug
{
public class Program
{
void M(Mapper<FromData, ToData> mapper)
{
// Intellisense is broken here when you type . after the x:
mapper.Map(x => x/* */.
}
}
public class Mapper<TTypeFrom, TTypeTo>
{
public void Map<TPropertyFrom, TPropertyTo>(
Expression<Func<TTypeFrom, TPropertyFrom>> from,
Expression<Func<TTypeTo, TPropertyTo>> to)
{ }
}
public class FromData
{
public int Int { get; set; }
public string String { get; set; }
}
public class ToData
{
public int Id { get; set; }
public string Name
{
get; set;
}
}
}";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
// We don't actually require any particular diagnostics, but these are what we get.
compilation.VerifyDiagnostics(
// (10,36): error CS1001: Identifier expected
// mapper.Map(x => x/* */.
Diagnostic(ErrorCode.ERR_IdentifierExpected, ""),
// (10,36): error CS1026: ) expected
// mapper.Map(x => x/* */.
Diagnostic(ErrorCode.ERR_CloseParenExpected, ""),
// (10,36): error CS1002: ; expected
// mapper.Map(x => x/* */.
Diagnostic(ErrorCode.ERR_SemicolonExpected, "")
);
var tree = compilation.SyntaxTrees.Single();
var model = compilation.GetSemanticModel(tree);
var xReference =
tree
.GetCompilationUnitRoot()
.DescendantNodes()
.OfType<ExpressionSyntax>()
.Where(e => e.ToFullString() == "x/* */")
.Last();
var typeInfo = model.GetTypeInfo(xReference);
Assert.NotNull(((ITypeSymbol)typeInfo.Type).GetMember("String"));
}
[WorkItem(722288, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/722288")]
[Fact]
public void CompletionInLambdaInIncompleteInvocation()
{
string source = @"
using System;
using System.Linq.Expressions;
public class SomeType
{
public string SomeProperty { get; set; }
}
public class IntelliSenseError
{
public static void Test1<T>(Expression<Func<T, object>> expr)
{
Console.WriteLine(((MemberExpression)expr.Body).Member.Name);
}
public static void Test2<T>(Expression<Func<T, object>> expr, bool additionalParameter)
{
Test1(expr);
}
public static void Main()
{
Test2<SomeType>(o => o/* */.
}
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
// We don't actually require any particular diagnostics, but these are what we get.
compilation.VerifyDiagnostics(
// (21,37): error CS1001: Identifier expected
// Test2<SomeType>(o => o/* */.
Diagnostic(ErrorCode.ERR_IdentifierExpected, ""),
// (21,37): error CS1026: ) expected
// Test2<SomeType>(o => o/* */.
Diagnostic(ErrorCode.ERR_CloseParenExpected, ""),
// (21,37): error CS1002: ; expected
// Test2<SomeType>(o => o/* */.
Diagnostic(ErrorCode.ERR_SemicolonExpected, "")
);
var tree = compilation.SyntaxTrees.Single();
var model = compilation.GetSemanticModel(tree);
var oReference =
tree
.GetCompilationUnitRoot()
.DescendantNodes()
.OfType<NameSyntax>()
.Where(e => e.ToFullString() == "o/* */")
.Last();
var typeInfo = model.GetTypeInfo(oReference);
Assert.NotNull(((ITypeSymbol)typeInfo.Type).GetMember("SomeProperty"));
}
[WorkItem(871896, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/871896")]
[Fact]
public void Bug871896()
{
string source = @"
using System.Threading;
using System.Threading.Tasks;
class TestDataPointBase
{
private readonly IVisualStudioIntegrationService integrationService;
protected void TryGetDocumentId(CancellationToken token)
{
DocumentId documentId = null;
if (!await Task.Run(() => this.integrationService.TryGetDocumentId(null, out documentId), token).ConfigureAwait(false))
{
}
}
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees.Single();
var model = compilation.GetSemanticModel(tree);
var oReference =
tree
.GetCompilationUnitRoot()
.DescendantNodes()
.OfType<ExpressionSyntax>()
.OrderByDescending(s => s.SpanStart);
foreach (var name in oReference)
{
CSharpExtensions.GetSymbolInfo(model, name);
}
// We should get a bunch of errors, but no asserts.
compilation.VerifyDiagnostics(
// (6,22): error CS0246: The type or namespace name 'IVisualStudioIntegrationService' could not be found (are you missing a using directive or an assembly reference?)
// private readonly IVisualStudioIntegrationService integrationService;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "IVisualStudioIntegrationService").WithArguments("IVisualStudioIntegrationService").WithLocation(6, 22),
// (9,9): error CS0246: The type or namespace name 'DocumentId' could not be found (are you missing a using directive or an assembly reference?)
// DocumentId documentId = null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "DocumentId").WithArguments("DocumentId").WithLocation(9, 9),
// (10,25): error CS0117: 'System.Threading.Tasks.Task' does not contain a definition for 'Run'
// if (!await Task.Run(() => this.integrationService.TryGetDocumentId(null, out documentId), token).ConfigureAwait(false))
Diagnostic(ErrorCode.ERR_NoSuchMember, "Run").WithArguments("System.Threading.Tasks.Task", "Run").WithLocation(10, 25),
// (10,14): error CS4033: The 'await' operator can only be used within an async method. Consider marking this method with the 'async' modifier and changing its return type to 'Task'.
// if (!await Task.Run(() => this.integrationService.TryGetDocumentId(null, out documentId), token).ConfigureAwait(false))
Diagnostic(ErrorCode.ERR_BadAwaitWithoutVoidAsyncMethod, "await Task.Run(() => this.integrationService.TryGetDocumentId(null, out documentId), token).ConfigureAwait(false)").WithLocation(10, 14),
// (6,54): warning CS0649: Field 'TestDataPointBase.integrationService' is never assigned to, and will always have its default value null
// private readonly IVisualStudioIntegrationService integrationService;
Diagnostic(ErrorCode.WRN_UnassignedInternalField, "integrationService").WithArguments("TestDataPointBase.integrationService", "null").WithLocation(6, 54)
);
}
[Fact, WorkItem(960755, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/960755")]
public void Bug960755_01()
{
var source = @"
using System.Collections.Generic;
class C
{
static void M(IList<C> c)
{
var tmp = new C();
tmp.M((a, b) => c.Add);
}
}
";
var tree = SyntaxFactory.ParseSyntaxTree(source, options: TestOptions.Regular9);
var comp = CreateCompilation(tree);
comp.VerifyDiagnostics(
// (9,22): error CS1660: Cannot convert lambda expression to type 'IList<C>' because it is not a delegate type
// tmp.M((a, b) => c.Add);
Diagnostic(ErrorCode.ERR_AnonMethToNonDel, "=>").WithArguments("lambda expression", "System.Collections.Generic.IList<C>").WithLocation(9, 22));
var model = comp.GetSemanticModel(tree);
var expr = (ExpressionSyntax)tree.GetCompilationUnitRoot().DescendantNodes().OfType<ParenthesizedLambdaExpressionSyntax>().Single().Body;
var symbolInfo = model.GetSymbolInfo(expr);
Assert.Null(symbolInfo.Symbol);
Assert.Equal("void System.Collections.Generic.ICollection<C>.Add(C item)", symbolInfo.CandidateSymbols.Single().ToTestDisplayString());
Assert.Equal(CandidateReason.OverloadResolutionFailure, symbolInfo.CandidateReason);
}
[Fact, WorkItem(960755, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/960755")]
public void Bug960755_02()
{
var source = @"
using System.Collections.Generic;
class C
{
static void M(IList<C> c)
{
int tmp = c.Add;
}
}
";
var tree = SyntaxFactory.ParseSyntaxTree(source);
var comp = CreateCompilation(tree);
var model = comp.GetSemanticModel(tree);
var expr = (ExpressionSyntax)tree.GetCompilationUnitRoot().DescendantNodes().OfType<VariableDeclaratorSyntax>().Single().Initializer.Value;
var symbolInfo = model.GetSymbolInfo(expr);
Assert.Null(symbolInfo.Symbol);
Assert.Equal("void System.Collections.Generic.ICollection<C>.Add(C item)", symbolInfo.CandidateSymbols.Single().ToTestDisplayString());
Assert.Equal(CandidateReason.OverloadResolutionFailure, symbolInfo.CandidateReason);
}
[Fact, WorkItem(960755, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/960755")]
public void Bug960755_03()
{
var source = @"
using System.Collections.Generic;
class C
{
static void M(IList<C> c)
{
var tmp = new C();
tmp.M((a, b) => c.Add);
}
static void M(System.Func<int, int, System.Action<C>> x)
{}
}
";
var tree = SyntaxFactory.ParseSyntaxTree(source);
var comp = CreateCompilation(tree);
var model = comp.GetSemanticModel(tree);
var expr = (ExpressionSyntax)tree.GetCompilationUnitRoot().DescendantNodes().OfType<ParenthesizedLambdaExpressionSyntax>().Single().Body;
var symbolInfo = model.GetSymbolInfo(expr);
Assert.Equal("void System.Collections.Generic.ICollection<C>.Add(C item)", symbolInfo.Symbol.ToTestDisplayString());
Assert.Equal(0, symbolInfo.CandidateSymbols.Length);
Assert.Equal(CandidateReason.None, symbolInfo.CandidateReason);
}
[Fact]
public void RefLambdaInferenceMethodArgument()
{
var text = @"
delegate ref int D();
class C
{
static void MD(D d) { }
static int i = 0;
static void M()
{
MD(() => ref i);
MD(() => { return ref i; });
MD(delegate { return ref i; });
}
}
";
CreateCompilationWithMscorlib461(text).VerifyDiagnostics();
}
[Fact]
public void RefLambdaInferenceDelegateCreation()
{
var text = @"
delegate ref int D();
class C
{
static int i = 0;
static void M()
{
var d = new D(() => ref i);
d = new D(() => { return ref i; });
d = new D(delegate { return ref i; });
}
}
";
CreateCompilationWithMscorlib461(text).VerifyDiagnostics();
}
[Fact]
public void RefLambdaInferenceOverloadedDelegateType()
{
var text = @"
delegate ref int D();
delegate int E();
class C
{
static void M(D d) { }
static void M(E e) { }
static int i = 0;
static void M()
{
M(() => ref i);
M(() => { return ref i; });
M(delegate { return ref i; });
M(() => i);
M(() => { return i; });
M(delegate { return i; });
}
}
";
CreateCompilationWithMscorlib461(text).VerifyDiagnostics();
}
[Fact]
public void RefLambdaInferenceArgumentBadRefReturn()
{
var text = @"
delegate int E();
class C
{
static void ME(E e) { }
static int i = 0;
static void M()
{
ME(() => ref i);
ME(() => { return ref i; });
ME(delegate { return ref i; });
}
}
";
CreateCompilationWithMscorlib461(text).VerifyDiagnostics(
// (11,22): error CS8149: By-reference returns may only be used in by-reference returning methods.
// ME(() => ref i);
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "i").WithLocation(11, 22),
// (12,20): error CS8149: By-reference returns may only be used in by-reference returning methods.
// ME(() => { return ref i; });
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(12, 20),
// (13,23): error CS8149: By-reference returns may only be used in by-reference returning methods.
// ME(delegate { return ref i; });
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(13, 23));
}
[Fact]
public void RefLambdaInferenceDelegateCreationBadRefReturn()
{
var text = @"
delegate int E();
class C
{
static int i = 0;
static void M()
{
var e = new E(() => ref i);
e = new E(() => { return ref i; });
e = new E(delegate { return ref i; });
}
}
";
CreateCompilationWithMscorlib461(text).VerifyDiagnostics(
// (9,33): error CS8149: By-reference returns may only be used in by-reference returning methods.
// var e = new E(() => ref i);
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "i").WithLocation(9, 33),
// (10,27): error CS8149: By-reference returns may only be used in by-reference returning methods.
// e = new E(() => { return ref i; });
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(10, 27),
// (11,30): error CS8149: By-reference returns may only be used in by-reference returning methods.
// e = new E(delegate { return ref i; });
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(11, 30));
}
[Fact]
public void RefLambdaInferenceMixedByValueAndByRefReturns()
{
var text = @"
delegate ref int D();
delegate int E();
class C
{
static void MD(D e) { }
static void ME(E e) { }
static int i = 0;
static void M()
{
MD(() => {
if (i == 0)
{
return ref i;
}
return i;
});
ME(() => {
if (i == 0)
{
return ref i;
}
return i;
});
}
}
";
CreateCompilationWithMscorlib461(text).VerifyDiagnostics(
// (18,13): error CS8150: By-value returns may only be used in by-value returning methods.
// return i;
Diagnostic(ErrorCode.ERR_MustHaveRefReturn, "return").WithLocation(18, 13),
// (23,17): error CS8149: By-reference returns may only be used in by-reference returning methods.
// return ref i;
Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(23, 17));
}
[WorkItem(1112875, "DevDiv")]
[WorkItem(1112875, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1112875")]
[Fact]
public void Bug1112875_1()
{
var comp = CreateCompilation(@"
using System;
class Program
{
static void Main()
{
ICloneable c = """";
Goo(() => (c.Clone()), null);
}
static void Goo(Action x, string y) { }
static void Goo(Func<object> x, object y) { Console.WriteLine(42); }
}", options: TestOptions.ReleaseExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "42");
}
[WorkItem(1112875, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1112875")]
[Fact]
public void Bug1112875_2()
{
var comp = CreateCompilation(@"
class Program
{
void M()
{
var d = new System.Action(() => (new object()));
}
}
");
comp.VerifyDiagnostics(
// (6,41): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
// var d = new System.Action(() => (new object()));
Diagnostic(ErrorCode.ERR_IllegalStatement, "(new object())").WithLocation(6, 41));
}
[WorkItem(1830, "https://github.com/dotnet/roslyn/issues/1830")]
[Fact]
public void FuncOfVoid()
{
var comp = CreateCompilation(@"
using System;
class Program
{
void M1<T>(Func<T> f) {}
void Main(string[] args)
{
M1(() => { return System.Console.Beep(); });
}
}
");
comp.VerifyDiagnostics(
// (8,27): error CS4029: Cannot return an expression of type 'void'
// M1(() => { return System.Console.Beep(); });
Diagnostic(ErrorCode.ERR_CantReturnVoid, "System.Console.Beep()").WithLocation(8, 27)
);
}
[Fact, WorkItem(1179899, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1179899")]
public void ParameterReference_01()
{
var src = @"
using System;
class Program
{
static Func<Program, string> stuff()
{
return a => a.
}
}
";
var compilation = CreateCompilation(src);
compilation.VerifyDiagnostics(
// (8,23): error CS1001: Identifier expected
// return a => a.
Diagnostic(ErrorCode.ERR_IdentifierExpected, "").WithLocation(8, 23),
// (8,23): error CS1002: ; expected
// return a => a.
Diagnostic(ErrorCode.ERR_SemicolonExpected, "").WithLocation(8, 23)
);
var tree = compilation.SyntaxTrees.Single();
var node = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "a").Single();
Assert.Equal("a.", node.Parent.ToString().Trim());
var semanticModel = compilation.GetSemanticModel(tree);
var symbolInfo = semanticModel.GetSymbolInfo(node);
Assert.Equal("Program a", symbolInfo.Symbol.ToTestDisplayString());
}
[Fact, WorkItem(1179899, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1179899")]
public void ParameterReference_02()
{
var src = @"
using System;
class Program
{
static void stuff()
{
Func<Program, string> l = a => a.
}
}
";
var compilation = CreateCompilation(src);
compilation.VerifyDiagnostics(
// (8,42): error CS1001: Identifier expected
// Func<Program, string> l = a => a.
Diagnostic(ErrorCode.ERR_IdentifierExpected, "").WithLocation(8, 42),
// (8,42): error CS1002: ; expected
// Func<Program, string> l = a => a.
Diagnostic(ErrorCode.ERR_SemicolonExpected, "").WithLocation(8, 42)
);
var tree = compilation.SyntaxTrees.Single();
var node = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "a").Single();
Assert.Equal("a.", node.Parent.ToString().Trim());
var semanticModel = compilation.GetSemanticModel(tree);
var symbolInfo = semanticModel.GetSymbolInfo(node);
Assert.Equal("Program a", symbolInfo.Symbol.ToTestDisplayString());
}
[Fact, WorkItem(1179899, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1179899")]
public void ParameterReference_03()
{
var src = @"
using System;
class Program
{
static void stuff()
{
M1(a => a.);
}
static void M1(Func<Program, string> l){}
}
";
var compilation = CreateCompilation(src);
compilation.VerifyDiagnostics(
// (8,20): error CS1001: Identifier expected
// M1(a => a.);
Diagnostic(ErrorCode.ERR_IdentifierExpected, ")").WithLocation(8, 20)
);
var tree = compilation.SyntaxTrees.Single();
var node = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "a").Single();
Assert.Equal("a.", node.Parent.ToString().Trim());
var semanticModel = compilation.GetSemanticModel(tree);
var symbolInfo = semanticModel.GetSymbolInfo(node);
Assert.Equal("Program a", symbolInfo.Symbol.ToTestDisplayString());
}
[Fact, WorkItem(1179899, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/1179899")]
public void ParameterReference_04()
{
var src = @"
using System;
class Program
{
static void stuff()
{
var l = (Func<Program, string>) (a => a.);
}
}
";
var compilation = CreateCompilation(src);
compilation.VerifyDiagnostics(
// (8,49): error CS1001: Identifier expected
// var l = (Func<Program, string>) (a => a.);
Diagnostic(ErrorCode.ERR_IdentifierExpected, ")").WithLocation(8, 49)
);
var tree = compilation.SyntaxTrees.Single();
var node = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "a").Single();
Assert.Equal("a.", node.Parent.ToString().Trim());
var semanticModel = compilation.GetSemanticModel(tree);
var symbolInfo = semanticModel.GetSymbolInfo(node);
Assert.Equal("Program a", symbolInfo.Symbol.ToTestDisplayString());
}
[Fact]
[WorkItem(3826, "https://github.com/dotnet/roslyn/issues/3826")]
public void ExpressionTreeSelfAssignmentShouldError()
{
var source = @"
using System;
using System.Linq.Expressions;
class Program
{
static void Main()
{
Expression<Func<int, int>> x = y => y = y;
}
}";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
compilation.VerifyDiagnostics(
// (9,45): warning CS1717: Assignment made to same variable; did you mean to assign something else?
// Expression<Func<int, int>> x = y => y = y;
Diagnostic(ErrorCode.WRN_AssignmentToSelf, "y = y").WithLocation(9, 45),
// (9,45): error CS0832: An expression tree may not contain an assignment operator
// Expression<Func<int, int>> x = y => y = y;
Diagnostic(ErrorCode.ERR_ExpressionTreeContainsAssignment, "y = y").WithLocation(9, 45));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void RefStructExpressionTree()
{
var text = @"
using System;
using System.Linq.Expressions;
public class Class1
{
public void Method1()
{
Method((Class1 c) => c.Method2(default(Struct1)));
}
public void Method2(Struct1 s1) { }
public static void Method<T>(Expression<Action<T>> expression) { }
}
public ref struct Struct1 { }
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (8,40): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'Struct1'.
// Method((Class1 c) => c.Method2(default(Struct1)));
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "default(Struct1)").WithArguments("Struct1").WithLocation(8, 40));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void RefStructDefaultExpressionTree()
{
var text = @"
using System;
using System.Linq.Expressions;
public class Class1
{
public void Method1()
{
Method((Class1 c) => c.Method2(default));
}
public void Method2(Struct1 s1) { }
public static void Method<T>(Expression<Action<T>> expression) { }
}
public ref struct Struct1 { }
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (8,40): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'Struct1'.
// Method((Class1 c) => c.Method2(default));
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "default").WithArguments("Struct1").WithLocation(8, 40));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void RefStructDefaultCastExpressionTree()
{
var text = @"
using System;
using System.Linq.Expressions;
public class Class1
{
public void Method1()
{
Method((Class1 c) => c.Method2((Struct1) default));
}
public void Method2(Struct1 s1) { }
public static void Method<T>(Expression<Action<T>> expression) { }
}
public ref struct Struct1 { }
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (8,50): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'Struct1'.
// Method((Class1 c) => c.Method2((Struct1) default));
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "default").WithArguments("Struct1").WithLocation(8, 50));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void RefStructNewExpressionTree()
{
var text = @"
using System;
using System.Linq.Expressions;
public class Class1
{
public void Method1()
{
Method((Class1 c) => c.Method2(new Struct1()));
}
public void Method2(Struct1 s1) { }
public static void Method<T>(Expression<Action<T>> expression) { }
}
public ref struct Struct1 { }
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (8,40): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'Struct1'.
// Method((Class1 c) => c.Method2(new Struct1()));
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "new Struct1()").WithArguments("Struct1").WithLocation(8, 40));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void RefStructParamExpressionTree()
{
var text = @"
using System.Linq.Expressions;
public delegate void Delegate1(Struct1 s);
public class Class1
{
public void Method1()
{
Method((Struct1 s) => Method2());
}
public void Method2() { }
public static void Method(Expression<Delegate1> expression) { }
}
public ref struct Struct1 { }
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (9,25): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'Struct1'.
// Method((Struct1 s) => Method2());
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "s").WithArguments("Struct1").WithLocation(9, 25));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void RefStructParamLambda()
{
var text = @"
public delegate void Delegate1(Struct1 s);
public class Class1
{
public void Method1()
{
Method((Struct1 s) => Method2());
}
public void Method2() { }
public static void Method(Delegate1 expression) { }
}
public ref struct Struct1 { }
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics();
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void TypedReferenceExpressionTree()
{
var text = @"
using System;
using System.Linq.Expressions;
public class Class1
{
public void Method1()
{
Method(() => Method2(default));
}
public void Method2(TypedReference tr) { }
public static void Method(Expression<Action> expression) { }
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (8,30): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'TypedReference'.
// Method(() => Method2(default));
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "default").WithArguments("TypedReference").WithLocation(8, 30));
}
[Fact, WorkItem(30776, "https://github.com/dotnet/roslyn/issues/30776")]
public void TypedReferenceParamExpressionTree()
{
var text = @"
using System;
using System.Linq.Expressions;
public delegate void Delegate1(TypedReference tr);
public class Class1
{
public void Method1()
{
Method((TypedReference tr) => Method2());
}
public void Method2() { }
public static void Method(Expression<Delegate1> expression) { }
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(text).VerifyDiagnostics(
// (9,32): error CS8640: Expression tree cannot contain value of ref struct or restricted type 'TypedReference'.
// Method((TypedReference tr) => Method2());
Diagnostic(ErrorCode.ERR_ExpressionTreeCantContainRefStruct, "tr").WithArguments("TypedReference").WithLocation(9, 32));
}
[Fact, WorkItem(5363, "https://github.com/dotnet/roslyn/issues/5363")]
public void ReturnInferenceCache_Dynamic_vs_Object_01()
{
var source =
@"
using System;
using System.Collections;
using System.Collections.Generic;
public static class Program
{
public static void Main(string[] args)
{
IEnumerable<dynamic> dynX = null;
// CS1061 'object' does not contain a definition for 'Text'...
// tooltip on 'var' shows IColumn instead of IEnumerable<dynamic>
var result = dynX.Select(_ => _.Text);
}
public static IColumn Select<TResult>(this IColumn source, Func<object, TResult> selector)
{
throw new NotImplementedException();
}
public static IEnumerable<S> Select<T, S>(this IEnumerable<T> source, Func<T, S> selector)
{
System.Console.WriteLine(""Select<T, S>"");
return null;
}
}
public interface IColumn { }
";
var compilation = CreateCompilation(source, new[] { CSharpRef }, options: TestOptions.ReleaseExe);
CompileAndVerify(compilation, expectedOutput: "Select<T, S>");
}
[Fact, WorkItem(5363, "https://github.com/dotnet/roslyn/issues/5363")]
public void ReturnInferenceCache_Dynamic_vs_Object_02()
{
var source =
@"
using System;
using System.Collections;
using System.Collections.Generic;
public static class Program
{
public static void Main(string[] args)
{
IEnumerable<dynamic> dynX = null;
// CS1061 'object' does not contain a definition for 'Text'...
// tooltip on 'var' shows IColumn instead of IEnumerable<dynamic>
var result = dynX.Select(_ => _.Text);
}
public static IEnumerable<S> Select<T, S>(this IEnumerable<T> source, Func<T, S> selector)
{
System.Console.WriteLine(""Select<T, S>"");
return null;
}
public static IColumn Select<TResult>(this IColumn source, Func<object, TResult> selector)
{
throw new NotImplementedException();
}
}
public interface IColumn { }
";
var compilation = CreateCompilation(source, new[] { CSharpRef }, options: TestOptions.ReleaseExe);
CompileAndVerify(compilation, expectedOutput: "Select<T, S>");
}
[Fact, WorkItem(1867, "https://github.com/dotnet/roslyn/issues/1867")]
public void SyntaxAndSemanticErrorInLambda()
{
var source =
@"
using System;
class C
{
public static void Main(string[] args)
{
Action a = () => { new X().ToString() };
a();
}
}
";
CreateCompilation(source).VerifyDiagnostics(
// (7,47): error CS1002: ; expected
// Action a = () => { new X().ToString() };
Diagnostic(ErrorCode.ERR_SemicolonExpected, "}").WithLocation(7, 47),
// (7,32): error CS0246: The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)
// Action a = () => { new X().ToString() };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "X").WithArguments("X").WithLocation(7, 32)
);
}
[Fact, WorkItem(4527, "https://github.com/dotnet/roslyn/issues/4527")]
public void AnonymousMethodExpressionWithoutParameterList()
{
var source =
@"
using System;
using System.Threading.Tasks;
namespace RoslynAsyncDelegate
{
class Program
{
static EventHandler MyEvent;
static void Main(string[] args)
{
MyEvent += async delegate { await Task.Delay(0); };
}
}
}
";
var compilation = CreateCompilationWithMscorlib461(source, options: TestOptions.DebugExe);
var tree = compilation.SyntaxTrees[0];
var model = compilation.GetSemanticModel(tree);
var node1 = tree.GetRoot().DescendantNodes().Where(n => n.IsKind(SyntaxKind.AnonymousMethodExpression)).Single();
Assert.Equal("async delegate { await Task.Delay(0); }", node1.ToString());
Assert.Equal("void System.EventHandler.Invoke(System.Object sender, System.EventArgs e)", model.GetTypeInfo(node1).ConvertedType.GetMembers("Invoke").Single().ToTestDisplayString());
var lambdaParameters = ((IMethodSymbol)(model.GetSymbolInfo(node1)).Symbol).Parameters;
Assert.Equal("System.Object <p0>", lambdaParameters[0].ToTestDisplayString());
Assert.Equal("System.EventArgs <p1>", lambdaParameters[1].ToTestDisplayString());
CompileAndVerify(compilation);
}
[Fact]
[WorkItem(1867, "https://github.com/dotnet/roslyn/issues/1867")]
public void TestLambdaWithError01()
{
var source =
@"using System.Linq;
class C { C() { string.Empty.Select(() => { new Unbound1 }); } }";
CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (2,58): error CS1526: A new expression requires (), [], or {} after type
// class C { C() { string.Empty.Select(() => { new Unbound1 }); } }
Diagnostic(ErrorCode.ERR_BadNewExpr, "}").WithLocation(2, 58),
// (2,58): error CS1002: ; expected
// class C { C() { string.Empty.Select(() => { new Unbound1 }); } }
Diagnostic(ErrorCode.ERR_SemicolonExpected, "}").WithLocation(2, 58),
// (2,49): error CS0246: The type or namespace name 'Unbound1' could not be found (are you missing a using directive or an assembly reference?)
// class C { C() { string.Empty.Select(() => { new Unbound1 }); } }
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Unbound1").WithArguments("Unbound1").WithLocation(2, 49)
);
}
[Fact]
[WorkItem(1867, "https://github.com/dotnet/roslyn/issues/1867")]
public void TestLambdaWithError02()
{
var source =
@"using System.Linq;
class C { C() { string.Empty.Select(() => { new Unbound1 ( ) }); } }";
CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (2,62): error CS1002: ; expected
// class C { C() { string.Empty.Select(() => { new Unbound1 ( ) }); } }
Diagnostic(ErrorCode.ERR_SemicolonExpected, "}").WithLocation(2, 62),
// (2,49): error CS0246: The type or namespace name 'Unbound1' could not be found (are you missing a using directive or an assembly reference?)
// class C { C() { string.Empty.Select(() => { new Unbound1 ( ) }); } }
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Unbound1").WithArguments("Unbound1").WithLocation(2, 49)
);
}
[Fact]
[WorkItem(1867, "https://github.com/dotnet/roslyn/issues/1867")]
public void TestLambdaWithError03()
{
var source =
@"using System.Linq;
class C { C() { string.Empty.Select(x => Unbound1, Unbound2 Unbound2); } }";
CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (2,61): error CS1003: Syntax error, ',' expected
// class C { C() { string.Empty.Select(x => Unbound1, Unbound2 Unbound2); } }
Diagnostic(ErrorCode.ERR_SyntaxError, "Unbound2").WithArguments(",").WithLocation(2, 61),
// (2,52): error CS0103: The name 'Unbound2' does not exist in the current context
// class C { C() { string.Empty.Select(x => Unbound1, Unbound2 Unbound2); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound2").WithArguments("Unbound2").WithLocation(2, 52),
// (2,61): error CS0103: The name 'Unbound2' does not exist in the current context
// class C { C() { string.Empty.Select(x => Unbound1, Unbound2 Unbound2); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound2").WithArguments("Unbound2").WithLocation(2, 61),
// (2,42): error CS0103: The name 'Unbound1' does not exist in the current context
// class C { C() { string.Empty.Select(x => Unbound1, Unbound2 Unbound2); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound1").WithArguments("Unbound1").WithLocation(2, 42)
);
}
[Fact]
[WorkItem(1867, "https://github.com/dotnet/roslyn/issues/1867")]
public void TestLambdaWithError04()
{
var source =
@"using System.Linq;
class C { C() { string.Empty.Select(x => Unbound1, Unbound2); } }";
CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (2,52): error CS0103: The name 'Unbound2' does not exist in the current context
// class C { C() { string.Empty.Select(x => Unbound1, Unbound2); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound2").WithArguments("Unbound2").WithLocation(2, 52),
// (2,42): error CS0103: The name 'Unbound1' does not exist in the current context
// class C { C() { string.Empty.Select(x => Unbound1, Unbound2); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound1").WithArguments("Unbound1").WithLocation(2, 42)
);
}
[Fact]
[WorkItem(1867, "https://github.com/dotnet/roslyn/issues/1867")]
public void TestLambdaWithError05()
{
var source =
@"using System.Linq;
class C { C() { Unbound2.Select(x => Unbound1); } }";
CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (2,17): error CS0103: The name 'Unbound2' does not exist in the current context
// class C { C() { Unbound2.Select(x => Unbound1); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound2").WithArguments("Unbound2").WithLocation(2, 17),
// (2,38): error CS0103: The name 'Unbound1' does not exist in the current context
// class C { C() { Unbound2.Select(x => Unbound1); } }
Diagnostic(ErrorCode.ERR_NameNotInContext, "Unbound1").WithArguments("Unbound1").WithLocation(2, 38)
);
}
[Fact]
[WorkItem(4480, "https://github.com/dotnet/roslyn/issues/4480")]
public void TestLambdaWithError06()
{
var source =
@"class Program
{
static void Main(string[] args)
{
// completion should work even in a syntactically invalid lambda
var handler = new MyDelegateType((s, e) => { e. });
}
}
public delegate void MyDelegateType(
object sender,
MyArgumentType e
);
public class MyArgumentType
{
public int SomePublicMember;
}";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source)
.VerifyDiagnostics(
// var handler = new MyDelegateType((s, e) => { e. });
Diagnostic(ErrorCode.ERR_IdentifierExpected, "}").WithLocation(6, 57),
// (6,57): error CS1002: ; expected
// var handler = new MyDelegateType((s, e) => { e. });
Diagnostic(ErrorCode.ERR_SemicolonExpected, "}").WithLocation(6, 57)
);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("e", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal("MyArgumentType", typeInfo.Type.Name);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.NotEmpty(typeInfo.Type.GetMembers("SomePublicMember"));
}
[Fact]
[WorkItem(11053, "https://github.com/dotnet/roslyn/issues/11053")]
[WorkItem(11358, "https://github.com/dotnet/roslyn/issues/11358")]
public void TestLambdaWithError07()
{
var source =
@"using System;
using System.Collections.Generic;
public static class Program
{
public static void Main()
{
var parameter = new List<string>();
var result = parameter.FirstOrDefault(x => x. );
}
}
public static class Enumerable
{
public static TSource FirstOrDefault<TSource>(this IEnumerable<TSource> source, TSource defaultValue)
{
return default(TSource);
}
public static TSource FirstOrDefault<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate, TSource defaultValue)
{
return default(TSource);
}
}";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (9,55): error CS1001: Identifier expected
// var result = parameter.FirstOrDefault(x => x. );
Diagnostic(ErrorCode.ERR_IdentifierExpected, ")").WithLocation(9, 55)
);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
[Fact]
[WorkItem(11053, "https://github.com/dotnet/roslyn/issues/11053")]
[WorkItem(11358, "https://github.com/dotnet/roslyn/issues/11358")]
public void TestLambdaWithError08()
{
var source =
@"using System;
using System.Collections.Generic;
public static class Program
{
public static void Main()
{
var parameter = new List<string>();
var result = parameter.FirstOrDefault(x => x. );
}
}
public static class Enumerable
{
public static TSource FirstOrDefault<TSource>(this IEnumerable<TSource> source, params TSource[] defaultValue)
{
return default(TSource);
}
public static TSource FirstOrDefault<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate, params TSource[] defaultValue)
{
return default(TSource);
}
}";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (9,55): error CS1001: Identifier expected
// var result = parameter.FirstOrDefault(x => x. );
Diagnostic(ErrorCode.ERR_IdentifierExpected, ")").WithLocation(9, 55)
);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
[Fact]
[WorkItem(11053, "https://github.com/dotnet/roslyn/issues/11053")]
[WorkItem(11358, "https://github.com/dotnet/roslyn/issues/11358")]
public void TestLambdaWithError09()
{
var source =
@"using System;
public static class Program
{
public static void Main()
{
var parameter = new MyList<string>();
var result = parameter.FirstOrDefault(x => x. );
}
}
public class MyList<TSource>
{
public TSource FirstOrDefault(TSource defaultValue)
{
return default(TSource);
}
public TSource FirstOrDefault(Func<TSource, bool> predicate, TSource defaultValue)
{
return default(TSource);
}
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (8,55): error CS1001: Identifier expected
// var result = parameter.FirstOrDefault(x => x. );
Diagnostic(ErrorCode.ERR_IdentifierExpected, ")").WithLocation(8, 55)
);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
[Fact]
[WorkItem(11053, "https://github.com/dotnet/roslyn/issues/11053")]
[WorkItem(11358, "https://github.com/dotnet/roslyn/issues/11358")]
public void TestLambdaWithError10()
{
var source =
@"using System;
public static class Program
{
public static void Main()
{
var parameter = new MyList<string>();
var result = parameter.FirstOrDefault(x => x. );
}
}
public class MyList<TSource>
{
public TSource FirstOrDefault(params TSource[] defaultValue)
{
return default(TSource);
}
public TSource FirstOrDefault(Func<TSource, bool> predicate, params TSource[] defaultValue)
{
return default(TSource);
}
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source).VerifyDiagnostics(
// (8,55): error CS1001: Identifier expected
// var result = parameter.FirstOrDefault(x => x. );
Diagnostic(ErrorCode.ERR_IdentifierExpected, ")").WithLocation(8, 55)
);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
[Fact]
[WorkItem(557, "https://github.com/dotnet/roslyn/issues/557")]
public void TestLambdaWithError11()
{
var source =
@"using System.Linq;
public static class Program
{
public static void Main()
{
var x = new {
X = """".Select(c => c.
Y = 0,
};
}
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("c", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal(TypeKind.Struct, typeInfo.Type.TypeKind);
Assert.Equal("Char", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("IsHighSurrogate")); // check it is the char we know and love
}
[Fact]
[WorkItem(5498, "https://github.com/dotnet/roslyn/issues/5498")]
public void TestLambdaWithError12()
{
var source =
@"using System.Linq;
class Program
{
static void Main(string[] args)
{
var z = args.Select(a => a.
var goo =
}
}";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambda = tree.GetCompilationUnitRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var eReference = lambda.Body.DescendantNodes().OfType<IdentifierNameSyntax>().First();
Assert.Equal("a", eReference.ToString());
var typeInfo = sm.GetTypeInfo(eReference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
[WorkItem(5498, "https://github.com/dotnet/roslyn/issues/5498")]
[WorkItem(11358, "https://github.com/dotnet/roslyn/issues/11358")]
[Fact]
public void TestLambdaWithError13()
{
// These tests ensure we attempt to perform type inference and bind a lambda expression
// argument even when there are too many or too few arguments to an invocation, in the
// case when there is more than one method in the method group.
// See https://github.com/dotnet/roslyn/issues/11901 for the case of one method in the group
var source =
@"using System;
class Program
{
static void Main(string[] args)
{
Thing<string> t = null;
t.X1(x => x, 1); // too many args
t.X2(x => x); // too few args
t.M2(string.Empty, x => x, 1); // too many args
t.M3(string.Empty, x => x); // too few args
}
}
public class Thing<T>
{
public void M2<T>(T x, Func<T, T> func) {}
public void M3<T>(T x, Func<T, T> func, T y) {}
// Ensure we have more than one method in the method group
public void M2() {}
public void M3() {}
}
public static class XThing
{
public static Thing<T> X1<T>(this Thing<T> self, Func<T, T> func) => null;
public static Thing<T> X2<T>(this Thing<T> self, Func<T, T> func, int i) => null;
// Ensure we have more than one method in the method group
public static void X1(this object self) {}
public static void X2(this object self) {}
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
{
var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", reference.ToString());
var typeInfo = sm.GetTypeInfo(reference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
}
[Fact]
[WorkItem(11901, "https://github.com/dotnet/roslyn/issues/11901")]
public void TestLambdaWithError15()
{
// These tests ensure we attempt to perform type inference and bind a lambda expression
// argument even when there are too many or too few arguments to an invocation, in the
// case when there is exactly one method in the method group.
var source =
@"using System;
class Program
{
static void Main(string[] args)
{
Thing<string> t = null;
t.X1(x => x, 1); // too many args
t.X2(x => x); // too few args
t.M2(string.Empty, x => x, 1); // too many args
t.M3(string.Empty, x => x); // too few args
}
}
public class Thing<T>
{
public void M2<T>(T x, Func<T, T> func) {}
public void M3<T>(T x, Func<T, T> func, T y) {}
}
public static class XThing
{
public static Thing<T> X1<T>(this Thing<T> self, Func<T, T> func) => null;
public static Thing<T> X2<T>(this Thing<T> self, Func<T, T> func, int i) => null;
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
{
var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", reference.ToString());
var typeInfo = sm.GetTypeInfo(reference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
}
[Fact]
[WorkItem(11901, "https://github.com/dotnet/roslyn/issues/11901")]
public void TestLambdaWithError16()
{
// These tests ensure we use the substituted method to bind a lambda expression
// argument even when there are too many or too few arguments to an invocation, in the
// case when there is exactly one method in the method group.
var source =
@"using System;
class Program
{
static void Main(string[] args)
{
Thing<string> t = null;
t.X1<string>(x => x, 1); // too many args
t.X2<string>(x => x); // too few args
t.M2<string>(string.Empty, x => x, 1); // too many args
t.M3<string>(string.Empty, x => x); // too few args
}
}
public class Thing<T>
{
public void M2<T>(T x, Func<T, T> func) {}
public void M3<T>(T x, Func<T, T> func, T y) {}
}
public static class XThing
{
public static Thing<T> X1<T>(this Thing<T> self, Func<T, T> func) => null;
public static Thing<T> X2<T>(this Thing<T> self, Func<T, T> func, int i) => null;
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
{
var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", reference.ToString());
var typeInfo = sm.GetTypeInfo(reference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
}
[Fact]
[WorkItem(12063, "https://github.com/dotnet/roslyn/issues/12063")]
public void TestLambdaWithError17()
{
var source =
@"using System;
class Program
{
static void Main(string[] args)
{
Ma(action: (x, y) => x.ToString(), t: string.Empty);
Mb(action: (x, y) => x.ToString(), t: string.Empty);
}
static void Ma<T>(T t, Action<T, T, int> action) { }
static void Mb<T>(T t, Action<T, T, int> action) { }
static void Mb() { }
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
{
var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", reference.ToString());
var typeInfo = sm.GetTypeInfo(reference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
}
[Fact]
[WorkItem(12063, "https://github.com/dotnet/roslyn/issues/12063")]
public void TestLambdaWithError18()
{
var source =
@"using System;
class Program
{
static void Main(string[] args)
{
Ma(string.Empty, (x, y) => x.ToString());
Mb(string.Empty, (x, y) => x.ToString());
}
static void Ma<T>(T t, Action<T, T, int> action) { }
static void Mb<T>(T t, Action<T, T, int> action) { }
static void Mb() { }
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
{
var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", reference.ToString());
var typeInfo = sm.GetTypeInfo(reference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
}
[Fact]
[WorkItem(12063, "https://github.com/dotnet/roslyn/issues/12063")]
public void TestLambdaWithError19()
{
var source =
@"using System;
using System.Linq.Expressions;
class Program
{
static void Main(string[] args)
{
Ma(string.Empty, (x, y) => x.ToString());
Mb(string.Empty, (x, y) => x.ToString());
Mc(string.Empty, (x, y) => x.ToString());
}
static void Ma<T>(T t, Expression<Action<T, T, int>> action) { }
static void Mb<T>(T t, Expression<Action<T, T, int>> action) { }
static void Mb<T>(T t, Action<T, T, int> action) { }
static void Mc<T>(T t, Expression<Action<T, T, int>> action) { }
static void Mc() { }
}
";
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
{
var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
Assert.Equal("x", reference.ToString());
var typeInfo = sm.GetTypeInfo(reference);
Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
Assert.Equal("String", typeInfo.Type.Name);
Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
}
}
// See MaxParameterListsForErrorRecovery.
[Fact]
public void BuildArgumentsForErrorRecovery_ManyOverloads()
{
BuildArgumentsForErrorRecovery_ManyOverloads_Internal(Binder.MaxParameterListsForErrorRecovery - 1, tooMany: false);
BuildArgumentsForErrorRecovery_ManyOverloads_Internal(Binder.MaxParameterListsForErrorRecovery, tooMany: true);
}
private void BuildArgumentsForErrorRecovery_ManyOverloads_Internal(int n, bool tooMany)
{
var builder = new StringBuilder();
builder.AppendLine("using System;");
for (int i = 0; i < n; i++)
{
builder.AppendLine($"class C{i} {{ }}");
}
builder.Append(
@"class A { }
class B { }
class C
{
void M()
{
F(1, (t, a, b, c) => { });
var o = this[(a, b, c) => { }];
}
");
// Too few parameters.
AppendLines(builder, n, i => $" void F<T>(T t, Action<T, A, C{i}> a) {{ }}");
AppendLines(builder, n, i => $" object this[Action<A, C{i}> a] => {i}");
// Type inference failure.
AppendLines(builder, n, i => $" void F<T, U>(T t, Action<T, U, C{i}> a) where U : T {{ }}");
// Too many parameters.
AppendLines(builder, n, i => $" void F<T>(T t, Action<T, A, B, C, C{i}> a) {{ }}");
AppendLines(builder, n, i => $" object this[Action<A, B, C, C{i}> a] => {i}");
builder.AppendLine("}");
var source = builder.ToString();
var compilation = CreateCompilationWithMscorlib40AndSystemCore(source);
var tree = compilation.SyntaxTrees[0];
var sm = compilation.GetSemanticModel(tree);
var lambdas = tree.GetRoot().DescendantNodes().OfType<ParenthesizedLambdaExpressionSyntax>().ToArray();
// F(1, (t, a, b, c) => { });
var lambda = lambdas[0];
var parameters = lambda.ParameterList.Parameters;
var parameter = (IParameterSymbol)sm.GetDeclaredSymbol(parameters[0]);
Assert.False(parameter.Type.IsErrorType());
Assert.Equal("System.Int32 t", parameter.ToTestDisplayString());
parameter = (IParameterSymbol)sm.GetDeclaredSymbol(parameters[1]);
Assert.False(parameter.Type.IsErrorType());
Assert.Equal("A a", parameter.ToTestDisplayString());
parameter = (IParameterSymbol)sm.GetDeclaredSymbol(parameters[3]);
Assert.Equal(tooMany, parameter.Type.IsErrorType());
Assert.Equal(tooMany ? "? c" : "C c", parameter.ToTestDisplayString());
// var o = this[(a, b, c) => { }];
lambda = lambdas[1];
parameters = lambda.ParameterList.Parameters;
parameter = (IParameterSymbol)sm.GetDeclaredSymbol(parameters[0]);
Assert.False(parameter.Type.IsErrorType());
Assert.Equal("A a", parameter.ToTestDisplayString());
parameter = (IParameterSymbol)sm.GetDeclaredSymbol(parameters[2]);
Assert.Equal(tooMany, parameter.Type.IsErrorType());
Assert.Equal(tooMany ? "? c" : "C c", parameter.ToTestDisplayString());
}
private static void AppendLines(StringBuilder builder, int n, Func<int, string> getLine)
{
for (int i = 0; i < n; i++)
{
builder.AppendLine(getLine(i));
}
}
[Fact]
[WorkItem(13797, "https://github.com/dotnet/roslyn/issues/13797")]
public void DelegateAsAction()
{
var source = @"
using System;
public static class C
{
public static void M() => Dispatch(delegate { });
public static T Dispatch<T>(Func<T> func) => default(T);
public static void Dispatch(Action func) { }
}";
var comp = CreateCompilation(source);
CompileAndVerify(comp);
}
[Fact, WorkItem(278481, "https://devdiv.visualstudio.com/DevDiv/_workitems?id=278481")]
public void LambdaReturningNull_1()
{
var src = @"
public static class ExtensionMethods
{
public static System.Linq.IQueryable<TResult> LeftOuterJoin<TOuter, TInner, TKey, TResult>(
this System.Linq.IQueryable<TOuter> outerValues,
System.Linq.IQueryable<TInner> innerValues,
System.Linq.Expressions.Expression<System.Func<TOuter, TKey>> outerKeySelector,
System.Linq.Expressions.Expression<System.Func<TInner, TKey>> innerKeySelector,
System.Linq.Expressions.Expression<System.Func<TOuter, TInner, TResult>> fullResultSelector,
System.Linq.Expressions.Expression<System.Func<TOuter, TResult>> partialResultSelector,
System.Collections.Generic.IEqualityComparer<TKey> comparer)
{ return null; }
public static System.Linq.IQueryable<TResult> LeftOuterJoin<TOuter, TInner, TKey, TResult>(
this System.Linq.IQueryable<TOuter> outerValues,
System.Linq.IQueryable<TInner> innerValues,
System.Linq.Expressions.Expression<System.Func<TOuter, TKey>> outerKeySelector,
System.Linq.Expressions.Expression<System.Func<TInner, TKey>> innerKeySelector,
System.Linq.Expressions.Expression<System.Func<TOuter, TInner, TResult>> fullResultSelector,
System.Linq.Expressions.Expression<System.Func<TOuter, TResult>> partialResultSelector)
{
System.Console.WriteLine(""1"");
return null;
}
public static System.Collections.Generic.IEnumerable<TResult> LeftOuterJoin<TOuter, TInner, TKey, TResult>(
this System.Collections.Generic.IEnumerable<TOuter> outerValues,
System.Linq.IQueryable<TInner> innerValues,
System.Func<TOuter, TKey> outerKeySelector,
System.Func<TInner, TKey> innerKeySelector,
System.Func<TOuter, TInner, TResult> fullResultSelector,
System.Func<TOuter, TResult> partialResultSelector)
{
System.Console.WriteLine(""2"");
return null;
}
public static System.Collections.Generic.IEnumerable<TResult> LeftOuterJoin<TOuter, TInner, TKey, TResult>(
this System.Collections.Generic.IEnumerable<TOuter> outerQueryable,
System.Collections.Generic.IEnumerable<TInner> innerQueryable,
System.Func<TOuter, TKey> outerKeySelector,
System.Func<TInner, TKey> innerKeySelector,
System.Func<TOuter, TInner, TResult> resultSelector)
{ return null; }
}
partial class C
{
public static void Main()
{
System.Linq.IQueryable<A> outerValue = null;
System.Linq.IQueryable<B> innerValues = null;
outerValue.LeftOuterJoin(innerValues,
co => co.id,
coa => coa.id,
(co, coa) => null,
co => co);
}
}
class A
{
public int id=2;
}
class B
{
public int id = 2;
}";
var comp = CreateCompilationWithMscorlib40AndSystemCore(src, options: TestOptions.DebugExe);
CompileAndVerify(comp, expectedOutput: "1");
}
[Fact, WorkItem(296550, "https://devdiv.visualstudio.com/DevDiv/_workitems?id=296550")]
public void LambdaReturningNull_2()
{
var src = @"
class Test1<T>
{
public void M1(System.Func<T> x) {}
public void M1<S>(System.Func<S> x) {}
public void M2<S>(System.Func<S> x) {}
public void M2(System.Func<T> x) {}
}
class Test2 : Test1<System.>
{
void Main()
{
M1(()=> null);
M2(()=> null);
}
}
";
var comp = CreateCompilation(src, options: TestOptions.DebugDll);
comp.VerifyDiagnostics(
// (10,32): error CS1001: Identifier expected
// class Test2 : Test1<System.>
Diagnostic(ErrorCode.ERR_IdentifierExpected, ">").WithLocation(10, 32)
);
}
[Fact, WorkItem(22662, "https://github.com/dotnet/roslyn/issues/22662")]
public void LambdaSquigglesArea()
{
var src = @"
class C
{
void M()
{
System.Func<bool, System.Action<bool>> x = x1 => x2 =>
{
error();
};
}
}
";
var comp = CreateCompilation(src);
comp.VerifyDiagnostics(
// (8,13): error CS0103: The name 'error' does not exist in the current context
// error();
Diagnostic(ErrorCode.ERR_NameNotInContext, "error").WithArguments("error").WithLocation(8, 13),
// (6,58): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// System.Func<bool, System.Action<bool>> x = x1 => x2 =>
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "x2 =>").WithArguments("lambda expression").WithLocation(6, 58)
);
}
[Fact, WorkItem(22662, "https://github.com/dotnet/roslyn/issues/22662")]
public void LambdaSquigglesAreaInAsync()
{
var src = @"
class C
{
void M()
{
System.Func<bool, System.Threading.Tasks.Task<System.Action<bool>>> x = async x1 => x2 =>
{
error();
};
}
}
";
var comp = CreateCompilation(src);
comp.VerifyDiagnostics(
// (8,13): error CS0103: The name 'error' does not exist in the current context
// error();
Diagnostic(ErrorCode.ERR_NameNotInContext, "error").WithArguments("error").WithLocation(8, 13),
// (6,93): error CS4010: Cannot convert async lambda expression to delegate type 'Task<Action<bool>>'. An async lambda expression may return void, Task or Task<T>, none of which are convertible to 'Task<Action<bool>>'.
// System.Func<bool, System.Threading.Tasks.Task<System.Action<bool>>> x = async x1 => x2 =>
Diagnostic(ErrorCode.ERR_CantConvAsyncAnonFuncReturns, "x2 =>").WithArguments("lambda expression", "System.Threading.Tasks.Task<System.Action<bool>>").WithLocation(6, 93),
// (6,90): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.
// System.Func<bool, System.Threading.Tasks.Task<System.Action<bool>>> x = async x1 => x2 =>
Diagnostic(ErrorCode.WRN_AsyncLacksAwaits, "=>").WithLocation(6, 90)
);
}
[Fact, WorkItem(22662, "https://github.com/dotnet/roslyn/issues/22662")]
public void DelegateSquigglesArea()
{
var src = @"
class C
{
void M()
{
System.Func<bool, System.Action<bool>> x = x1 => delegate(bool x2)
{
error();
};
}
}
";
var comp = CreateCompilation(src);
comp.VerifyDiagnostics(
// (8,13): error CS0103: The name 'error' does not exist in the current context
// error();
Diagnostic(ErrorCode.ERR_NameNotInContext, "error").WithArguments("error").WithLocation(8, 13),
// (6,58): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// System.Func<bool, System.Action<bool>> x = x1 => delegate(bool x2)
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "delegate(bool x2)").WithArguments("lambda expression").WithLocation(6, 58)
);
}
[Fact, WorkItem(22662, "https://github.com/dotnet/roslyn/issues/22662")]
public void DelegateWithoutArgumentsSquigglesArea()
{
var src = @"
class C
{
void M()
{
System.Func<bool, System.Action> x = x1 => delegate
{
error();
};
}
}
";
var comp = CreateCompilation(src);
comp.VerifyDiagnostics(
// (8,13): error CS0103: The name 'error' does not exist in the current context
// error();
Diagnostic(ErrorCode.ERR_NameNotInContext, "error").WithArguments("error").WithLocation(8, 13),
// (6,52): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// System.Func<bool, System.Action> x = x1 => delegate
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "delegate").WithArguments("lambda expression").WithLocation(6, 52)
);
}
[Fact]
public void ThrowExpression_Lambda()
{
var src = @"using System;
class C
{
public static void Main()
{
Action a = () => throw new Exception(""1"");
try
{
a();
}
catch (Exception ex)
{
Console.Write(ex.Message);
}
Func<int, int> b = x => throw new Exception(""2"");
try
{
b(0);
}
catch (Exception ex)
{
Console.Write(ex.Message);
}
b = (int x) => throw new Exception(""3"");
try
{
b(0);
}
catch (Exception ex)
{
Console.Write(ex.Message);
}
b = (x) => throw new Exception(""4"");
try
{
b(0);
}
catch (Exception ex)
{
Console.Write(ex.Message);
}
}
}";
var comp = CreateCompilationWithMscorlib40AndSystemCore(src, options: TestOptions.DebugExe);
CompileAndVerify(comp, expectedOutput: "1234");
}
[Fact, WorkItem(23883, "https://github.com/dotnet/roslyn/issues/23883")]
public void InMalformedEmbeddedStatement_01()
{
var source = @"
class Program
{
void method1()
{
if (method2())
.Any(b => b.ContentType, out var chars)
{
}
}
}
";
var tree = SyntaxFactory.ParseSyntaxTree(source);
var comp = CreateCompilation(tree);
ExpressionSyntax contentType = tree.GetCompilationUnitRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "ContentType").Single();
var model = comp.GetSemanticModel(tree);
Assert.Equal("ContentType", contentType.ToString());
Assert.Null(model.GetSymbolInfo(contentType).Symbol);
Assert.Equal(TypeKind.Error, model.GetTypeInfo(contentType).Type.TypeKind);
ExpressionSyntax b = tree.GetCompilationUnitRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "b").Single();
model = comp.GetSemanticModel(tree);
Assert.Equal("b", b.ToString());
ISymbol symbol = model.GetSymbolInfo(b).Symbol;
Assert.Equal(SymbolKind.Parameter, symbol.Kind);
Assert.Equal("? b", symbol.ToTestDisplayString());
Assert.Equal(TypeKind.Error, model.GetTypeInfo(b).Type.TypeKind);
ParameterSyntax parameterSyntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ParameterSyntax>().Single();
model = comp.GetSemanticModel(tree);
symbol = model.GetDeclaredSymbol(parameterSyntax);
Assert.Equal(SymbolKind.Parameter, symbol.Kind);
Assert.Equal("? b", symbol.ToTestDisplayString());
}
[Fact, WorkItem(23883, "https://github.com/dotnet/roslyn/issues/23883")]
public void InMalformedEmbeddedStatement_02()
{
var source = @"
class Program
{
void method1()
{
if (method2())
.Any(b => b.ContentType, out var chars)
{
}
}
}
";
var tree = SyntaxFactory.ParseSyntaxTree(source);
var comp = CreateCompilation(tree);
ExpressionSyntax contentType = tree.GetCompilationUnitRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "ContentType").Single();
var model = comp.GetSemanticModel(tree);
Assert.Equal("ContentType", contentType.ToString());
var lambda = (IMethodSymbol)model.GetEnclosingSymbol(contentType.SpanStart);
Assert.Equal(MethodKind.AnonymousFunction, lambda.MethodKind);
ExpressionSyntax b = tree.GetCompilationUnitRoot().DescendantNodes().OfType<IdentifierNameSyntax>().Where(id => id.Identifier.ValueText == "b").Single();
model = comp.GetSemanticModel(tree);
Assert.Equal("b", b.ToString());
lambda = (IMethodSymbol)model.GetEnclosingSymbol(b.SpanStart);
Assert.Equal(MethodKind.AnonymousFunction, lambda.MethodKind);
model = comp.GetSemanticModel(tree);
ParameterSyntax parameterSyntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ParameterSyntax>().Single();
Assert.Equal("void Program.method1()", model.GetEnclosingSymbol(parameterSyntax.SpanStart).ToTestDisplayString());
}
[Fact]
public void ShadowNames_Local()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static void M()
{
Action a1 = () => { object x = 0; }; // local
Action<string> a2 = x => { }; // parameter
Action<string> a3 = (string x) => { }; // parameter
object x = null;
Action a4 = () => { void x() { } }; // method
Action a5 = () => { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (9,36): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a1 = () => { object x = 0; }; // local
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(9, 36),
// (10,29): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> a2 = x => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(10, 29),
// (11,37): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> a3 = (string x) => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 37),
// (13,34): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a4 = () => { void x() { } }; // method
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(13, 34),
// (14,38): error CS1931: The range variable 'x' conflicts with a previous declaration of 'x'
// Action a5 = () => { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableOverrides, "x").WithArguments("x").WithLocation(14, 38));
comp = CreateCompilation(source, parseOptions: TestOptions.Regular8);
comp.VerifyDiagnostics();
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_Parameter()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static Action<object> F = (object x) =>
{
Action a1 = () => { object x = 0; }; // local
Action<string> a2 = x => { }; // parameter
Action<string> a3 = (string x) => { }; // parameter
Action a4 = () => { void x() { } }; // method
Action a5 = () => { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
};
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (9,36): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a1 = () => { object x = 0; }; // local
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(9, 36),
// (10,29): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> a2 = x => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(10, 29),
// (11,37): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> a3 = (string x) => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 37),
// (13,38): error CS1931: The range variable 'x' conflicts with a previous declaration of 'x'
// Action a5 = () => { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableOverrides, "x").WithArguments("x").WithLocation(13, 38));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_TypeParameter()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static void M<@x>()
{
Action a1 = () => { object x = 0; }; // local
Action<string> a2 = x => { }; // parameter
Action<string> a3 = (string x) => { }; // parameter
Action a4 = () => { void x() { } }; // method
Action a5 = () => { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (9,36): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action a1 = () => { object x = 0; }; // local
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(9, 36),
// (10,29): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action<string> a2 = x => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(10, 29),
// (11,37): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action<string> a3 = (string x) => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(11, 37),
// (12,34): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action a4 = () => { void x() { } }; // method
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(12, 34),
// (13,38): error CS1948: The range variable 'x' cannot have the same name as a method type parameter
// Action a5 = () => { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableSameAsTypeParam, "x").WithArguments("x").WithLocation(13, 38));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_QueryParameter()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static void Main(string[] args)
{
_ = from x in args select (Action)(() => { object x = 0; }); // local
_ = from x in args select (Action<string>)(x => { }); // parameter
_ = from x in args select (Action<string>)((string x) => { }); // parameter
_ = from x in args select (Action)(() => { void x() { } }); // method
_ = from x in args select (Action)(() => { _ = from x in new[] { 1, 2, 3 } select x; }); // range variable
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (9,59): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// _ = from x in args select (Action)(() => { object x = 0; }); // local
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(9, 59),
// (10,52): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// _ = from x in args select (Action<string>)(x => { }); // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(10, 52),
// (11,60): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// _ = from x in args select (Action<string>)((string x) => { }); // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 60),
// (13,61): error CS1931: The range variable 'x' conflicts with a previous declaration of 'x'
// _ = from x in args select (Action)(() => { _ = from x in new[] { 1, 2, 3 } select x; }); // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableOverrides, "x").WithArguments("x").WithLocation(13, 61));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_Local_Delegate()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static void M()
{
object x = null;
Action a1 = delegate() { object x = 0; }; // local
Action<string> a2 = delegate(string x) { }; // parameter
Action a3 = delegate() { void x() { } }; // method
Action a4 = delegate() { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (10,41): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a1 = delegate() { object x = 0; }; // local
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(10, 41),
// (11,45): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> a2 = delegate(string x) { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 45),
// (12,39): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a3 = delegate() { void x() { } }; // method
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(12, 39),
// (13,43): error CS1931: The range variable 'x' conflicts with a previous declaration of 'x'
// Action a4 = delegate() { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableOverrides, "x").WithArguments("x").WithLocation(13, 43));
comp = CreateCompilation(source, parseOptions: TestOptions.Regular8);
comp.VerifyDiagnostics();
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_Parameter_Delegate()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static Action<object> F = (object x) =>
{
Action a1 = delegate() { object x = 0; }; // local
Action<string> a2 = delegate(string x) { }; // parameter
Action a3 = delegate() { void x() { } }; // method
Action a4 = delegate() { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
};
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (9,41): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a1 = delegate() { object x = 0; }; // local
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(9, 41),
// (10,45): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> a2 = delegate(string x) { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(10, 45),
// (12,43): error CS1931: The range variable 'x' conflicts with a previous declaration of 'x'
// Action a4 = delegate() { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableOverrides, "x").WithArguments("x").WithLocation(12, 43));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_TypeParameter_Delegate()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
using System.Linq;
class Program
{
static void M<@x>()
{
Action a1 = delegate() { object x = 0; }; // local
Action<string> a2 = delegate(string x) { }; // parameter
Action a3 = delegate() { void x() { } }; // method
Action a4 = delegate() { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (9,41): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action a1 = delegate() { object x = 0; }; // local
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(9, 41),
// (10,45): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action<string> a2 = delegate(string x) { }; // parameter
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(10, 45),
// (11,39): error CS0412: 'x': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action a3 = delegate() { void x() { } }; // method
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "x").WithArguments("x").WithLocation(11, 39),
// (12,43): error CS1948: The range variable 'x' cannot have the same name as a method type parameter
// Action a4 = delegate() { _ = from x in new[] { 1, 2, 3 } select x; }; // range variable
Diagnostic(ErrorCode.ERR_QueryRangeVariableSameAsTypeParam, "x").WithArguments("x").WithLocation(12, 43));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_LambdaInsideLambda()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M<T>(object x)
{
Action a1 = () =>
{
Action b1 = () => { object x = 1; }; // local
Action<string> b2 = (string x) => { }; // parameter
};
Action a2 = () =>
{
Action b3 = () => { object T = 3; }; // local
Action<string> b4 = T => { }; // parameter
};
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (10,40): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action b1 = () => { object x = 1; }; // local
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(10, 40),
// (11,41): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<string> b2 = (string x) => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 41),
// (15,40): error CS0412: 'T': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action b3 = () => { object T = 3; }; // local
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "T").WithArguments("T").WithLocation(15, 40),
// (16,33): error CS0412: 'T': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action<string> b4 = T => { }; // parameter
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "T").WithArguments("T").WithLocation(16, 33));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_Underscore_01()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M()
{
Func<int, Func<int, int>> f = _ => _ => _;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (8,44): error CS0136: A local or parameter named '_' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Func<int, Func<int, int>> f = _ => _ => _;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "_").WithArguments("_").WithLocation(8, 44));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_Underscore_02()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M()
{
Func<int, int, int> f = (_, _) => 0;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (8,37): error CS8370: Feature 'lambda discard parameters' is not available in C# 7.3. Please use language version 9.0 or greater.
// Func<int, int, int> f = (_, _) => 0;
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "_").WithArguments("lambda discard parameters", "9.0").WithLocation(8, 37));
comp = CreateCompilation(source);
comp.VerifyEmitDiagnostics();
}
[Fact]
public void ShadowNames_Nested_01()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M()
{
Func<int, Func<int, Func<int, int>>> f = x => x => x => x;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (8,55): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Func<int, Func<int, Func<int, int>>> f = x => x => x => x;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(8, 55),
// (8,60): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Func<int, Func<int, Func<int, int>>> f = x => x => x => x;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(8, 60));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_Nested_02()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M()
{
Func<int, int, int, Func<int, int, Func<int, int, int>>> f = (x, y, z) => (_, x) => (y, _) => x + y + z + _;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (8,87): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Func<int, int, int, Func<int, int, Func<int, int, int>>> f = (x, y, z) => (_, x) => (y, _) => x + y + z + _;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(8, 87),
// (8,94): error CS0136: A local or parameter named 'y' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Func<int, int, int, Func<int, int, Func<int, int, int>>> f = (x, y, z) => (_, x) => (y, _) => x + y + z + _;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "y").WithArguments("y").WithLocation(8, 94),
// (8,97): error CS0136: A local or parameter named '_' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Func<int, int, int, Func<int, int, Func<int, int, int>>> f = (x, y, z) => (_, x) => (y, _) => x + y + z + _;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "_").WithArguments("_").WithLocation(8, 97));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_LambdaInsideLocalFunction_01()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M()
{
void F1()
{
object x = null;
Action a1 = () => { int x = 0; };
}
void F2<T>()
{
Action a2 = () => { int T = 0; };
}
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (11,37): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action a1 = () => { int x = 0; };
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 37),
// (15,37): error CS0412: 'T': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action a2 = () => { int T = 0; };
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "T").WithArguments("T").WithLocation(15, 37));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void ShadowNames_LambdaInsideLocalFunction_02()
{
var source =
@"#pragma warning disable 0219
#pragma warning disable 8321
using System;
class Program
{
static void M<T>()
{
object x = null;
void F()
{
Action<int> a1 = (int x) =>
{
Action b1 = () => { int T = 0; };
};
Action a2 = () =>
{
int x = 0;
Action<int> b2 = (int T) => { };
};
}
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(
// (11,35): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// Action<int> a1 = (int x) =>
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(11, 35),
// (13,41): error CS0412: 'T': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action b1 = () => { int T = 0; };
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "T").WithArguments("T").WithLocation(13, 41),
// (17,21): error CS0136: A local or parameter named 'x' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
// int x = 0;
Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "x").WithArguments("x").WithLocation(17, 21),
// (18,39): error CS0412: 'T': a parameter, local variable, or local function cannot have the same name as a method type parameter
// Action<int> b2 = (int T) => { };
Diagnostic(ErrorCode.ERR_LocalSameNameAsTypeParam, "T").WithArguments("T").WithLocation(18, 39));
comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaAttributes_01()
{
var sourceA =
@"using System;
class A : Attribute { }
class B : Attribute { }
partial class Program
{
static Delegate D1() => (Action)([A] () => { });
static Delegate D2(int x) => (Func<int, int, int>)((int y, [A][B] int z) => x);
static Delegate D3() => (Action<int, object>)(([A]_, y) => { });
Delegate D4() => (Func<int>)([return: A][B] () => GetHashCode());
}";
var sourceB =
@"using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
partial class Program
{
static string GetAttributeString(object a)
{
return a.GetType().FullName;
}
static void Report(Delegate d)
{
var m = d.Method;
var forMethod = ToString(""method"", m.GetCustomAttributes(inherit: false));
var forReturn = ToString(""return"", m.ReturnTypeCustomAttributes.GetCustomAttributes(inherit: false));
var forParameters = ToString(""parameter"", m.GetParameters().SelectMany(p => p.GetCustomAttributes(inherit: false)));
Console.WriteLine(""{0}:{1}{2}{3}"", m.Name, forMethod, forReturn, forParameters);
}
static string ToString(string target, IEnumerable<object> attributes)
{
var builder = new StringBuilder();
foreach (var attribute in attributes)
builder.Append($"" [{target}: {attribute}]"");
return builder.ToString();
}
static void Main()
{
Report(D1());
Report(D2(0));
Report(D3());
Report(new Program().D4());
}
}";
var comp = CreateCompilation(new[] { sourceA, sourceB }, parseOptions: TestOptions.Regular10, options: TestOptions.ReleaseExe);
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>();
var pairs = exprs.Select(e => (e, model.GetSymbolInfo(e).Symbol)).ToArray();
var expectedAttributes = new[]
{
"[A] () => { }: [method: A]",
"(int y, [A][B] int z) => x: [parameter: A] [parameter: B]",
"([A]_, y) => { }: [parameter: A]",
"[return: A][B] () => GetHashCode(): [method: B] [return: A]",
};
AssertEx.Equal(expectedAttributes, pairs.Select(p => getAttributesInternal(p.Item1, p.Item2)));
AssertEx.Equal(expectedAttributes, pairs.Select(p => getAttributesPublic(p.Item1, p.Item2)));
CompileAndVerify(comp, expectedOutput:
@"<D1>b__0_0: [method: A]
<D2>b__0: [parameter: A] [parameter: B]
<D3>b__2_0: [parameter: A]
<D4>b__3_0: [method: System.Runtime.CompilerServices.CompilerGeneratedAttribute] [method: B] [return: A]");
static string getAttributesInternal(LambdaExpressionSyntax expr, ISymbol symbol)
{
var method = symbol.GetSymbol<MethodSymbol>();
return format(expr, method.GetAttributes(), method.GetReturnTypeAttributes(), method.Parameters.SelectMany(p => p.GetAttributes()));
}
static string getAttributesPublic(LambdaExpressionSyntax expr, ISymbol symbol)
{
var method = (IMethodSymbol)symbol;
return format(expr, method.GetAttributes(), method.GetReturnTypeAttributes(), method.Parameters.SelectMany(p => p.GetAttributes()));
}
static string format(LambdaExpressionSyntax expr, IEnumerable<object> methodAttributes, IEnumerable<object> returnAttributes, IEnumerable<object> parameterAttributes)
{
var forMethod = toString("method", methodAttributes);
var forReturn = toString("return", returnAttributes);
var forParameters = toString("parameter", parameterAttributes);
return $"{expr}:{forMethod}{forReturn}{forParameters}";
}
static string toString(string target, IEnumerable<object> attributes)
{
var builder = new StringBuilder();
foreach (var attribute in attributes)
builder.Append($" [{target}: {attribute}]");
return builder.ToString();
}
}
[Fact]
public void LambdaAttributes_02()
{
var source =
@"using System;
class AAttribute : Attribute { }
class BAttribute : Attribute { }
class C
{
static void Main()
{
Action<object, object> a;
a = [A, B] (x, y) => { };
a = ([A] x, [B] y) => { };
a = (object x, [A][B] object y) => { };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (9,13): error CS8773: Feature 'lambda attributes' is not available in C# 9.0. Please use language version 10.0 or greater.
// a = [A, B] (x, y) => { };
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "[A, B]").WithArguments("lambda attributes", "10.0").WithLocation(9, 13),
// (10,14): error CS8773: Feature 'lambda attributes' is not available in C# 9.0. Please use language version 10.0 or greater.
// a = ([A] x, [B] y) => { };
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "[A]").WithArguments("lambda attributes", "10.0").WithLocation(10, 14),
// (10,21): error CS8773: Feature 'lambda attributes' is not available in C# 9.0. Please use language version 10.0 or greater.
// a = ([A] x, [B] y) => { };
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "[B]").WithArguments("lambda attributes", "10.0").WithLocation(10, 21),
// (11,24): error CS8773: Feature 'lambda attributes' is not available in C# 9.0. Please use language version 10.0 or greater.
// a = (object x, [A][B] object y) => { };
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "[A]").WithArguments("lambda attributes", "10.0").WithLocation(11, 24),
// (11,27): error CS8773: Feature 'lambda attributes' is not available in C# 9.0. Please use language version 10.0 or greater.
// a = (object x, [A][B] object y) => { };
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "[B]").WithArguments("lambda attributes", "10.0").WithLocation(11, 27));
comp = CreateCompilation(source, parseOptions: TestOptions.Regular10);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaAttributes_03()
{
var source =
@"using System;
class AAttribute : Attribute { }
class BAttribute : Attribute { }
class C
{
static void Main()
{
Action<object, object> a = delegate (object x, [A][B] object y) { };
Func<object, object> f = [A][B] x => x;
}
}";
var expectedDiagnostics = new[]
{
// (8,56): error CS7014: Attributes are not valid in this context.
// Action<object, object> a = delegate (object x, [A][B] object y) { };
Diagnostic(ErrorCode.ERR_AttributesNotAllowed, "[A]").WithLocation(8, 56),
// (8,59): error CS7014: Attributes are not valid in this context.
// Action<object, object> a = delegate (object x, [A][B] object y) { };
Diagnostic(ErrorCode.ERR_AttributesNotAllowed, "[B]").WithLocation(8, 59),
// (9,34): error CS8916: Attributes on lambda expressions require a parenthesized parameter list.
// Func<object, object> f = [A][B] x => x;
Diagnostic(ErrorCode.ERR_AttributesRequireParenthesizedLambdaExpression, "[A]").WithLocation(9, 34),
// (9,37): error CS8916: Attributes on lambda expressions require a parenthesized parameter list.
// Func<object, object> f = [A][B] x => x;
Diagnostic(ErrorCode.ERR_AttributesRequireParenthesizedLambdaExpression, "[B]").WithLocation(9, 37)
};
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(expectedDiagnostics);
comp = CreateCompilation(source, parseOptions: TestOptions.Regular10);
comp.VerifyDiagnostics(expectedDiagnostics);
}
[Fact]
public void LambdaAttributes_04()
{
var sourceA =
@"namespace N1
{
class A1Attribute : System.Attribute { }
}
namespace N2
{
class A2Attribute : System.Attribute { }
}";
var sourceB =
@"using N1;
using N2;
class Program
{
static void Main()
{
System.Action a1 = [A1] () => { };
System.Action<object> a2 = ([A2] object obj) => { };
}
}";
var comp = CreateCompilation(new[] { sourceA, sourceB }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaAttributes_05()
{
var source =
@"class Program
{
static void Main()
{
System.Action a1 = [A1] () => { };
System.Func<object> a2 = [return: A2] () => null;
System.Action<object> a3 = ([A3] object obj) => { };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (5,29): error CS0246: The type or namespace name 'A1Attribute' could not be found (are you missing a using directive or an assembly reference?)
// System.Action a1 = [A1] () => { };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "A1").WithArguments("A1Attribute").WithLocation(5, 29),
// (5,29): error CS0246: The type or namespace name 'A1' could not be found (are you missing a using directive or an assembly reference?)
// System.Action a1 = [A1] () => { };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "A1").WithArguments("A1").WithLocation(5, 29),
// (6,43): error CS0246: The type or namespace name 'A2Attribute' could not be found (are you missing a using directive or an assembly reference?)
// System.Func<object> a2 = [return: A2] () => null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "A2").WithArguments("A2Attribute").WithLocation(6, 43),
// (6,43): error CS0246: The type or namespace name 'A2' could not be found (are you missing a using directive or an assembly reference?)
// System.Func<object> a2 = [return: A2] () => null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "A2").WithArguments("A2").WithLocation(6, 43),
// (7,38): error CS0246: The type or namespace name 'A3Attribute' could not be found (are you missing a using directive or an assembly reference?)
// System.Action<object> a3 = ([A3] object obj) => { };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "A3").WithArguments("A3Attribute").WithLocation(7, 38),
// (7,38): error CS0246: The type or namespace name 'A3' could not be found (are you missing a using directive or an assembly reference?)
// System.Action<object> a3 = ([A3] object obj) => { };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "A3").WithArguments("A3").WithLocation(7, 38));
}
[Fact]
public void LambdaAttributes_06()
{
var source =
@"using System;
class AAttribute : Attribute
{
public AAttribute(Action a) { }
}
[A([B] () => { })]
class BAttribute : Attribute
{
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (6,11): error CS1003: Syntax error, ',' expected
// [A([B] () => { })]
Diagnostic(ErrorCode.ERR_SyntaxError, "=>").WithArguments(",").WithLocation(6, 11),
// (6,16): error CS1026: ) expected
// [A([B] () => { })]
Diagnostic(ErrorCode.ERR_CloseParenExpected, "}").WithLocation(6, 16),
// (6,16): error CS1003: Syntax error, ']' expected
// [A([B] () => { })]
Diagnostic(ErrorCode.ERR_SyntaxError, "}").WithArguments("]").WithLocation(6, 16),
// (6,16): error CS1022: Type or namespace definition, or end-of-file expected
// [A([B] () => { })]
Diagnostic(ErrorCode.ERR_EOFExpected, "}").WithLocation(6, 16),
// (6,17): error CS1022: Type or namespace definition, or end-of-file expected
// [A([B] () => { })]
Diagnostic(ErrorCode.ERR_EOFExpected, ")").WithLocation(6, 17));
}
[Fact]
public void LambdaAttributes_BadAttributeLocation()
{
var source =
@"using System;
[AttributeUsage(AttributeTargets.Property)]
class PropAttribute : Attribute { }
[AttributeUsage(AttributeTargets.Method)]
class MethodAttribute : Attribute { }
[AttributeUsage(AttributeTargets.ReturnValue)]
class ReturnAttribute : Attribute { }
[AttributeUsage(AttributeTargets.Parameter)]
class ParamAttribute : Attribute { }
[AttributeUsage(AttributeTargets.GenericParameter)]
class TypeParamAttribute : Attribute { }
class Program
{
static void Main()
{
Action<object> a =
[Prop] // 1
[Return] // 2
[Method]
[return: Prop] // 3
[return: Return]
[return: Method] // 4
(
[Param]
[TypeParam] // 5
object o) =>
{
};
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (23,14): error CS0592: Attribute 'Prop' is not valid on this declaration type. It is only valid on 'property, indexer' declarations.
// [Prop] // 1
Diagnostic(ErrorCode.ERR_AttributeOnBadSymbolType, "Prop").WithArguments("Prop", "property, indexer").WithLocation(23, 14),
// (24,14): error CS0592: Attribute 'Return' is not valid on this declaration type. It is only valid on 'return' declarations.
// [Return] // 2
Diagnostic(ErrorCode.ERR_AttributeOnBadSymbolType, "Return").WithArguments("Return", "return").WithLocation(24, 14),
// (26,22): error CS0592: Attribute 'Prop' is not valid on this declaration type. It is only valid on 'property, indexer' declarations.
// [return: Prop] // 3
Diagnostic(ErrorCode.ERR_AttributeOnBadSymbolType, "Prop").WithArguments("Prop", "property, indexer").WithLocation(26, 22),
// (28,22): error CS0592: Attribute 'Method' is not valid on this declaration type. It is only valid on 'method' declarations.
// [return: Method] // 4
Diagnostic(ErrorCode.ERR_AttributeOnBadSymbolType, "Method").WithArguments("Method", "method").WithLocation(28, 22),
// (31,14): error CS0592: Attribute 'TypeParam' is not valid on this declaration type. It is only valid on 'type parameter' declarations.
// [TypeParam] // 5
Diagnostic(ErrorCode.ERR_AttributeOnBadSymbolType, "TypeParam").WithArguments("TypeParam", "type parameter").WithLocation(31, 14));
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var lambda = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var symbol = (IMethodSymbol)model.GetSymbolInfo(lambda).Symbol;
Assert.NotNull(symbol);
verifyAttributes(symbol.GetAttributes(), "PropAttribute", "ReturnAttribute", "MethodAttribute");
verifyAttributes(symbol.GetReturnTypeAttributes(), "PropAttribute", "ReturnAttribute", "MethodAttribute");
verifyAttributes(symbol.Parameters[0].GetAttributes(), "ParamAttribute", "TypeParamAttribute");
void verifyAttributes(ImmutableArray<AttributeData> attributes, params string[] expectedAttributeNames)
{
var actualAttributes = attributes.SelectAsArray(a => a.AttributeClass.GetSymbol());
var expectedAttributes = expectedAttributeNames.Select(n => comp.GetTypeByMetadataName(n));
AssertEx.Equal(expectedAttributes, actualAttributes);
}
}
[Fact]
public void LambdaAttributes_AttributeSemanticModel()
{
var source =
@"using System;
class AAttribute : Attribute { }
class BAttribute : Attribute { }
class CAttribute : Attribute { }
class DAttribute : Attribute { }
class Program
{
static void Main()
{
Action a = [A] () => { };
Func<object> b = [return: B] () => null;
Action<object> c = ([C] object obj) => { };
Func<object, object> d = [D] x => x;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (13,34): error CS8916: Attributes on lambda expressions require a parenthesized parameter list.
// Func<object, object> d = [D] x => x;
Diagnostic(ErrorCode.ERR_AttributesRequireParenthesizedLambdaExpression, "[D]").WithLocation(13, 34));
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var attributeSyntaxes = tree.GetRoot().DescendantNodes().OfType<AttributeSyntax>().ToImmutableArray();
Assert.Equal(4, attributeSyntaxes.Length);
verify(attributeSyntaxes[0], "AAttribute");
verify(attributeSyntaxes[1], "BAttribute");
verify(attributeSyntaxes[2], "CAttribute");
verify(attributeSyntaxes[3], "DAttribute");
void verify(AttributeSyntax attributeSyntax, string expectedAttributeName)
{
var expectedAttributeConstructor = comp.GetTypeByMetadataName(expectedAttributeName).InstanceConstructors.Single().GetPublicSymbol();
var expectedAttributeType = expectedAttributeConstructor.ContainingType;
var typeInfo = model.GetTypeInfo(attributeSyntax);
Assert.Equal(expectedAttributeType, typeInfo.Type);
Assert.Equal(expectedAttributeType, typeInfo.ConvertedType);
var symbol = model.GetSymbolInfo(attributeSyntax).Symbol;
Assert.Equal(expectedAttributeConstructor, symbol);
}
}
[Theory]
[InlineData("Action a = [A] () => { };")]
[InlineData("Func<object> f = [return: A] () => null;")]
[InlineData("Action<int> a = ([A] int i) => { };")]
public void LambdaAttributes_SpeculativeSemanticModel(string statement)
{
string source =
$@"using System;
class AAttribute : Attribute {{ }}
class Program
{{
static void Main()
{{
{statement}
}}
}}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var a = (IdentifierNameSyntax)tree.GetRoot().DescendantNodes().OfType<AttributeSyntax>().Single().Name;
Assert.Equal("A", a.Identifier.Text);
var attrInfo = model.GetSymbolInfo(a);
var attrType = comp.GetMember<NamedTypeSymbol>("AAttribute").GetPublicSymbol();
var attrCtor = attrType.GetMember(".ctor");
Assert.Equal(attrCtor, attrInfo.Symbol);
// Assert that this is also true for the speculative semantic model
var newTree = SyntaxFactory.ParseSyntaxTree(source + " ");
var m = newTree.GetRoot().DescendantNodes().OfType<MethodDeclarationSyntax>().Single();
Assert.True(model.TryGetSpeculativeSemanticModelForMethodBody(m.Body.SpanStart, m, out model));
a = (IdentifierNameSyntax)newTree.GetRoot().DescendantNodes().OfType<AttributeSyntax>().Single().Name;
Assert.Equal("A", a.Identifier.Text);
var info = model.GetSymbolInfo(a);
Assert.Equal(attrCtor, info.Symbol);
}
[Fact]
public void LambdaAttributes_DisallowedAttributes()
{
var source =
@"using System;
using System.Runtime.CompilerServices;
namespace System.Runtime.CompilerServices
{
public class IsReadOnlyAttribute : Attribute { }
public class IsUnmanagedAttribute : Attribute { }
public class IsByRefLikeAttribute : Attribute { }
public class NullableContextAttribute : Attribute { public NullableContextAttribute(byte b) { } }
}
class Program
{
static void Main()
{
Action a =
[IsReadOnly] // 1
[IsUnmanaged] // 2
[IsByRefLike] // 3
[Extension] // 4
[NullableContext(0)] // 5
() => { };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (15,14): error CS8335: Do not use 'System.Runtime.CompilerServices.IsReadOnlyAttribute'. This is reserved for compiler usage.
// [IsReadOnly] // 1
Diagnostic(ErrorCode.ERR_ExplicitReservedAttr, "IsReadOnly").WithArguments("System.Runtime.CompilerServices.IsReadOnlyAttribute").WithLocation(15, 14),
// (16,14): error CS8335: Do not use 'System.Runtime.CompilerServices.IsUnmanagedAttribute'. This is reserved for compiler usage.
// [IsUnmanaged] // 2
Diagnostic(ErrorCode.ERR_ExplicitReservedAttr, "IsUnmanaged").WithArguments("System.Runtime.CompilerServices.IsUnmanagedAttribute").WithLocation(16, 14),
// (17,14): error CS8335: Do not use 'System.Runtime.CompilerServices.IsByRefLikeAttribute'. This is reserved for compiler usage.
// [IsByRefLike] // 3
Diagnostic(ErrorCode.ERR_ExplicitReservedAttr, "IsByRefLike").WithArguments("System.Runtime.CompilerServices.IsByRefLikeAttribute").WithLocation(17, 14),
// (18,14): error CS1112: Do not use 'System.Runtime.CompilerServices.ExtensionAttribute'. Use the 'this' keyword instead.
// [Extension] // 4
Diagnostic(ErrorCode.ERR_ExplicitExtension, "Extension").WithLocation(18, 14),
// (19,14): error CS8335: Do not use 'System.Runtime.CompilerServices.NullableContextAttribute'. This is reserved for compiler usage.
// [NullableContext(0)] // 5
Diagnostic(ErrorCode.ERR_ExplicitReservedAttr, "NullableContext(0)").WithArguments("System.Runtime.CompilerServices.NullableContextAttribute").WithLocation(19, 14));
}
[Fact]
public void LambdaAttributes_DisallowedSecurityAttributes()
{
var source =
@"using System;
using System.Security;
class Program
{
static void Main()
{
Action a =
[SecurityCritical] // 1
[SecuritySafeCriticalAttribute] // 2
async () => { }; // 3
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,14): error CS4030: Security attribute 'SecurityCritical' cannot be applied to an Async method.
// [SecurityCritical] // 1
Diagnostic(ErrorCode.ERR_SecurityCriticalOrSecuritySafeCriticalOnAsync, "SecurityCritical").WithArguments("SecurityCritical").WithLocation(8, 14),
// (9,14): error CS4030: Security attribute 'SecuritySafeCriticalAttribute' cannot be applied to an Async method.
// [SecuritySafeCriticalAttribute] // 2
Diagnostic(ErrorCode.ERR_SecurityCriticalOrSecuritySafeCriticalOnAsync, "SecuritySafeCriticalAttribute").WithArguments("SecuritySafeCriticalAttribute").WithLocation(9, 14),
// (10,22): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.
// async () => { }; // 3
Diagnostic(ErrorCode.WRN_AsyncLacksAwaits, "=>").WithLocation(10, 22));
}
[Fact]
public void LambdaAttributes_ObsoleteAttribute()
{
var source =
@"using System;
class Program
{
static void Report(Action a)
{
foreach (var attribute in a.Method.GetCustomAttributes(inherit: false))
Console.Write(attribute);
}
static void Main()
{
Report([Obsolete] () => { });
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: "System.ObsoleteAttribute");
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var expr = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var symbol = model.GetSymbolInfo(expr).Symbol;
Assert.Equal("System.ObsoleteAttribute", symbol.GetAttributes().Single().ToString());
}
[Fact]
public void LambdaParameterAttributes_Conditional()
{
var source =
@"using System;
using System.Diagnostics;
class Program
{
static void Report(Action a)
{
}
static void Main()
{
Report([Conditional(""DEBUG"")] static () => { });
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview, options: TestOptions.ReleaseExe);
comp.VerifyDiagnostics(
// (10,17): error CS0577: The Conditional attribute is not valid on 'lambda expression' because it is a constructor, destructor, operator, lambda expression, or explicit interface implementation
// Report([Conditional("DEBUG")] static () => { });
Diagnostic(ErrorCode.ERR_ConditionalOnSpecialMethod, @"Conditional(""DEBUG"")").WithArguments("lambda expression").WithLocation(10, 17));
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
var lambda = exprs.SelectAsArray(e => GetLambdaSymbol(model, e)).Single();
Assert.Equal(new[] { "DEBUG" }, lambda.GetAppliedConditionalSymbols());
}
[Fact]
public void LambdaAttributes_WellKnownAttributes()
{
var sourceA =
@"using System;
using System.Runtime.InteropServices;
using System.Security;
class Program
{
static void Main()
{
Action a1 = [DllImport(""MyModule.dll"")] static () => { };
Action a2 = [DynamicSecurityMethod] () => { };
Action a3 = [SuppressUnmanagedCodeSecurity] () => { };
Func<object> a4 = [return: MarshalAs((short)0)] () => null;
}
}";
var sourceB =
@"namespace System.Security
{
internal class DynamicSecurityMethodAttribute : Attribute { }
}";
var comp = CreateCompilation(new[] { sourceA, sourceB }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,22): error CS0601: The DllImport attribute must be specified on a method marked 'static' and 'extern'
// Action a1 = [DllImport("MyModule.dll")] static () => { };
Diagnostic(ErrorCode.ERR_DllImportOnInvalidMethod, "DllImport").WithLocation(8, 22));
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
Assert.Equal(4, exprs.Length);
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.Null(lambdas[0].GetDllImportData()); // [DllImport] is ignored if there are errors.
Assert.True(lambdas[1].RequiresSecurityObject);
Assert.True(lambdas[2].HasDeclarativeSecurity);
Assert.Equal(default, lambdas[3].ReturnValueMarshallingInformation.UnmanagedType);
}
[Fact]
public void LambdaAttributes_Permissions()
{
var source =
@"#pragma warning disable 618
using System;
using System.Security.Permissions;
class Program
{
static void Main()
{
Action a1 = [PermissionSet(SecurityAction.Deny)] () => { };
}
}";
var comp = CreateCompilationWithMscorlib40(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
var lambda = exprs.SelectAsArray(e => GetLambdaSymbol(model, e)).Single();
Assert.NotEmpty(lambda.GetSecurityInformation());
}
[Fact]
public void LambdaAttributes_NullableAttributes_01()
{
var source =
@"using System;
using System.Diagnostics.CodeAnalysis;
class Program
{
static void Main()
{
Func<object> a1 = [return: MaybeNull][return: NotNull] () => null;
Func<object, object> a2 = [return: NotNullIfNotNull(""obj"")] (object obj) => obj;
Func<bool> a4 = [MemberNotNull(""x"")][MemberNotNullWhen(false, ""y"")][MemberNotNullWhen(true, ""z"")] () => true;
}
}";
var comp = CreateCompilation(
new[] { source, MaybeNullAttributeDefinition, NotNullAttributeDefinition, NotNullIfNotNullAttributeDefinition, MemberNotNullAttributeDefinition, MemberNotNullWhenAttributeDefinition },
parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
Assert.Equal(3, exprs.Length);
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.Equal(FlowAnalysisAnnotations.MaybeNull | FlowAnalysisAnnotations.NotNull, lambdas[0].ReturnTypeFlowAnalysisAnnotations);
Assert.Equal(new[] { "obj" }, lambdas[1].ReturnNotNullIfParameterNotNull);
Assert.Equal(new[] { "x" }, lambdas[2].NotNullMembers);
Assert.Equal(new[] { "y" }, lambdas[2].NotNullWhenFalseMembers);
Assert.Equal(new[] { "z" }, lambdas[2].NotNullWhenTrueMembers);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_02()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
class Program
{
static void Main()
{
Func<object> a1 = [return: MaybeNull] () => null;
Func<object?> a2 = [return: NotNull] () => null;
}
}";
var comp = CreateCompilation(new[] { source, MaybeNullAttributeDefinition, NotNullAttributeDefinition }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,27): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<object>' (possibly because of nullability attributes).
// Func<object> a1 = [return: MaybeNull] () => null;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "System.Func<object>").WithLocation(8, 27),
// (9,28): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<object?>' (possibly because of nullability attributes).
// Func<object?> a2 = [return: NotNull] () => null;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] () =>").WithArguments("lambda expression", "System.Func<object?>").WithLocation(9, 28),
// (9,52): warning CS8603: Possible null reference return.
// Func<object?> a2 = [return: NotNull] () => null;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(9, 52)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_AnonymousFunctionConversion_Return()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate object D1();
[return: MaybeNull] delegate object D2();
[return: NotNull] delegate object? D3();
class Program
{
static void Main()
{
Func<object> f1 = [return: MaybeNull] () => null; // 1
D1 f2 = [return: MaybeNull] () => null; // 2
D2 f3 = [return: MaybeNull] () => null;
D3 f4 = [return: MaybeNull] () => null; // 3
Func<object> f5 = [return: NotNull] () => null;
D1 f6 = [return: NotNull] () => null;
D2 f7 = [return: NotNull] () => null; // 4
D3 f8 = [return: NotNull] () => null;
Func<object?> f9 = [return: NotNull] () => null; // 5
D1 f10 = [return: NotNull] object? () => null;
D2 f11 = [return: NotNull] object? () => null; // 6
D3 f12 = [return: NotNull] object? () => null;
}
}";
var comp = CreateCompilation(new[] { source, MaybeNullAttributeDefinition, NotNullAttributeDefinition });
comp.VerifyDiagnostics(
// (13,27): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<object>' (possibly because of nullability attributes).
// Func<object> f1 = [return: MaybeNull] () => null; // 1
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "System.Func<object>").WithLocation(13, 27),
// (14,17): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// D1 f2 = [return: MaybeNull] () => null; // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "D1").WithLocation(14, 17),
// (16,17): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 f4 = [return: MaybeNull] () => null; // 3
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "D3").WithLocation(16, 17),
// (18,51): warning CS8603: Possible null reference return.
// Func<object> f5 = [return: NotNull] () => null;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(18, 51),
// (19,41): warning CS8603: Possible null reference return.
// D1 f6 = [return: NotNull] () => null;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(19, 41),
// (20,17): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 f7 = [return: NotNull] () => null; // 4
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] () =>").WithArguments("lambda expression", "D2").WithLocation(20, 17),
// (20,41): warning CS8603: Possible null reference return.
// D2 f7 = [return: NotNull] () => null; // 4
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(20, 41),
// (21,41): warning CS8603: Possible null reference return.
// D3 f8 = [return: NotNull] () => null;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(21, 41),
// (23,28): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<object?>' (possibly because of nullability attributes).
// Func<object?> f9 = [return: NotNull] () => null; // 5
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] () =>").WithArguments("lambda expression", "System.Func<object?>").WithLocation(23, 28),
// (23,52): warning CS8603: Possible null reference return.
// Func<object?> f9 = [return: NotNull] () => null; // 5
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(23, 52),
// (24,50): warning CS8603: Possible null reference return.
// D1 f10 = [return: NotNull] object? () => null;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(24, 50),
// (25,18): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 f11 = [return: NotNull] object? () => null; // 6
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] object? () =>").WithArguments("lambda expression", "D2").WithLocation(25, 18),
// (25,50): warning CS8603: Possible null reference return.
// D2 f11 = [return: NotNull] object? () => null; // 6
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(25, 50),
// (26,50): warning CS8603: Possible null reference return.
// D3 f12 = [return: NotNull] object? () => null;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(26, 50)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_AnonymousFunctionConversion_Return_Suppressed()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate object D1();
[return: MaybeNull] delegate object D2();
[return: NotNull] delegate object? D3();
class Program
{
static void Main()
{
Func<object> f1 = ([return: MaybeNull] () => null)!;
D1 f2 = ([return: MaybeNull] () => null)!;
D3 f4 = ([return: MaybeNull] () => null)!;
D2 f7 = ([return: NotNull] () => null)!;
Func<object?> f9 = ([return: NotNull] () => null)!;
D2 f11 = ([return: NotNull] object? () => null)!;
}
}";
var comp = CreateCompilation(new[] { source, MaybeNullAttributeDefinition, NotNullAttributeDefinition });
comp.VerifyDiagnostics(
// (17,42): warning CS8603: Possible null reference return.
// D2 f7 = ([return: NotNull] () => null)!;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(17, 42),
// (19,53): warning CS8603: Possible null reference return.
// Func<object?> f9 = ([return: NotNull] () => null)!;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(19, 53),
// (20,51): warning CS8603: Possible null reference return.
// D2 f11 = ([return: NotNull] object? () => null)!;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(20, 51)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_DelegateCreation_Return()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate object D1();
[return: MaybeNull] delegate object D2();
[return: NotNull] delegate object? D3();
class Program
{
static void Main()
{
_ = new Func<object>([return: MaybeNull] () => null); // 1
_ = new D1([return: MaybeNull] () => null); // 2
_ = new D2([return: MaybeNull] () => null);
_ = new D3([return: MaybeNull] () => null); // 3
_ = new Func<object>([return: NotNull] () => null);
_ = new D1([return: NotNull] () => null);
_ = new D2([return: NotNull] () => null); // 4
_ = new D3([return: NotNull] () => null);
_ = new Func<object?>([return: NotNull] () => null); // 5
_ = new D1([return: NotNull] object? () => null);
_ = new D2([return: NotNull] object? () => null); // 6
_ = new D3([return: NotNull] object? () => null);
}
}";
var comp = CreateCompilation(new[] { source, MaybeNullAttributeDefinition, NotNullAttributeDefinition });
comp.VerifyDiagnostics(
// (13,30): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<object>' (possibly because of nullability attributes).
// _ = new Func<object>([return: MaybeNull] () => null); // 1
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "System.Func<object>").WithLocation(13, 30),
// (14,20): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// _ = new D1([return: MaybeNull] () => null); // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "D1").WithLocation(14, 20),
// (16,20): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// _ = new D3([return: MaybeNull] () => null); // 3
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: MaybeNull] () =>").WithArguments("lambda expression", "D3").WithLocation(16, 20),
// (18,54): warning CS8603: Possible null reference return.
// _ = new Func<object>([return: NotNull] () => null);
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(18, 54),
// (19,44): warning CS8603: Possible null reference return.
// _ = new D1([return: NotNull] () => null);
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(19, 44),
// (20,20): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// _ = new D2([return: NotNull] () => null); // 4
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] () =>").WithArguments("lambda expression", "D2").WithLocation(20, 20),
// (20,44): warning CS8603: Possible null reference return.
// _ = new D2([return: NotNull] () => null); // 4
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(20, 44),
// (21,44): warning CS8603: Possible null reference return.
// _ = new D3([return: NotNull] () => null);
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(21, 44),
// (23,31): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<object?>' (possibly because of nullability attributes).
// _ = new Func<object?>([return: NotNull] () => null); // 5
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] () =>").WithArguments("lambda expression", "System.Func<object?>").WithLocation(23, 31),
// (23,55): warning CS8603: Possible null reference return.
// _ = new Func<object?>([return: NotNull] () => null); // 5
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(23, 55),
// (24,52): warning CS8603: Possible null reference return.
// _ = new D1([return: NotNull] object? () => null);
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(24, 52),
// (25,20): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// _ = new D2([return: NotNull] object? () => null); // 6
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "[return: NotNull] object? () =>").WithArguments("lambda expression", "D2").WithLocation(25, 20),
// (25,52): warning CS8603: Possible null reference return.
// _ = new D2([return: NotNull] object? () => null); // 6
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(25, 52),
// (26,52): warning CS8603: Possible null reference return.
// _ = new D3([return: NotNull] object? () => null);
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(26, 52)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_AnonymousFunctionConversion_Parameter()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate void D1(object o);
delegate void D2([AllowNull] object o);
delegate void D3([DisallowNull] object? o);
class Program
{
static void Main()
{
Action<object> x1 = ([AllowNull] object o) => { }; // 1
D1 x2 = ([AllowNull] object o) => { }; // 2
D2 x3 = ([AllowNull] object o) => { };
D3 x4 = ([AllowNull] object o) => { }; // 3
Action<object> x5 = ([DisallowNull] object o) => { };
D1 x6 = ([DisallowNull] object o) => { };
D2 x7 = ([DisallowNull] object o) => { }; // 4
D3 x8 = ([DisallowNull] object o) => { };
Action<object?> x9 = ([DisallowNull] object? o) => { }; // 5
D1 x10 = ([DisallowNull] object? o) => { };
D2 x11 = ([DisallowNull] object? o) => { }; // 6
D3 x12 = ([DisallowNull] object? o) => { };
}
}";
var comp = CreateCompilation(new[] { source, AllowNullAttributeDefinition, DisallowNullAttributeDefinition });
comp.VerifyDiagnostics(
// (13,29): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'Action<object>' (possibly because of nullability attributes).
// Action<object> x1 = ([AllowNull] object o) => { }; // 1
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] object o) =>").WithArguments("o", "lambda expression", "System.Action<object>").WithLocation(13, 29),
// (14,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// D1 x2 = ([AllowNull] object o) => { }; // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] object o) =>").WithArguments("o", "lambda expression", "D1").WithLocation(14, 17),
// (16,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 x4 = ([AllowNull] object o) => { }; // 3
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] object o) =>").WithArguments("o", "lambda expression", "D3").WithLocation(16, 17),
// (20,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 x7 = ([DisallowNull] object o) => { }; // 4
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] object o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(20, 17),
// (23,30): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'Action<object?>' (possibly because of nullability attributes).
// Action<object?> x9 = ([DisallowNull] object? o) => { }; // 5
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] object? o) =>").WithArguments("o", "lambda expression", "System.Action<object?>").WithLocation(23, 30),
// (25,18): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 x11 = ([DisallowNull] object? o) => { }; // 6
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] object? o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(25, 18)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_AnonymousFunctionConversion_Parameter_WithoutType()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate void D1(object o);
delegate void D2([AllowNull] object o);
delegate void D3([DisallowNull] object? o);
class Program
{
static void Main()
{
Action<object> x1 = (o) => { o.ToString(); };
Action<object?> x2 = (o) => { o.ToString(); }; // 1
D1 x3 = (o) => { o.ToString(); };
D2 x4 = (o) => { o.ToString(); }; // 2
D3 x5 = (o) => { o.ToString(); }; // 3, 4
}
}";
var comp = CreateCompilation(new[] { source, AllowNullAttributeDefinition, DisallowNullAttributeDefinition });
comp.VerifyDiagnostics(
// (14,39): warning CS8602: Dereference of a possibly null reference.
// Action<object?> x2 = (o) => { o.ToString(); }; // 1
Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "o").WithLocation(14, 39),
// (16,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 x4 = (o) => { o.ToString(); }; // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "(o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(16, 17),
// (17,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 x5 = (o) => { o.ToString(); }; // 3, 4
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "(o) =>").WithArguments("o", "lambda expression", "D3").WithLocation(17, 17),
// (17,26): warning CS8602: Dereference of a possibly null reference.
// D3 x5 = (o) => { o.ToString(); }; // 3, 4
Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "o").WithLocation(17, 26)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_AnonymousFunctionConversion_Parameter_ConditionalAttributes()
{
var source =
@"#nullable enable
using System.Diagnostics.CodeAnalysis;
delegate bool D1([MaybeNullWhen(true)] out object o);
delegate bool D2([MaybeNullWhen(false)] out object o);
delegate bool D3([NotNullWhen(true)] out object? o);
class Program
{
static void Main()
{
D1 x1 = bool ([MaybeNullWhen(true)] out object o) => throw null!;
D1 x2 = bool ([MaybeNullWhen(false)] out object o) => throw null!; // 1
D1 x3 = bool ([MaybeNull] out object o) => throw null!; // 2
D1 x4 = bool (out object? o) => throw null!; // 3
D2 x5 = bool ([MaybeNullWhen(true)] out object o) => throw null!; // 4
D2 x6 = bool ([MaybeNullWhen(false)] out object o) => throw null!;
D2 x7 = bool ([MaybeNull] out object o) => throw null!; // 5
D2 x8 = bool (out object? o) => throw null!; // 6
D3 x9 = bool ([MaybeNullWhen(true)] out object o) => throw null!; // 7
D3 x10 = bool ([MaybeNullWhen(false)] out object o) => throw null!;
D3 x11 = bool ([MaybeNull] out object o) => throw null!; // 8
D3 x12 = bool (out object? o) => throw null!; // 9
}
}";
var comp = CreateCompilation(new[] { source, MaybeNullWhenAttributeDefinition, NotNullWhenAttributeDefinition, MaybeNullAttributeDefinition });
comp.VerifyDiagnostics(
// (13,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// D1 x2 = bool ([MaybeNullWhen(false)] out object o) => throw null!; // 1
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool ([MaybeNullWhen(false)] out object o) =>").WithArguments("o", "lambda expression", "D1").WithLocation(13, 17),
// (14,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// D1 x3 = bool ([MaybeNull] out object o) => throw null!; // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool ([MaybeNull] out object o) =>").WithArguments("o", "lambda expression", "D1").WithLocation(14, 17),
// (15,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// D1 x4 = bool (out object? o) => throw null!; // 3
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool (out object? o) =>").WithArguments("o", "lambda expression", "D1").WithLocation(15, 17),
// (17,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 x5 = bool ([MaybeNullWhen(true)] out object o) => throw null!; // 4
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool ([MaybeNullWhen(true)] out object o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(17, 17),
// (19,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 x7 = bool ([MaybeNull] out object o) => throw null!; // 5
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool ([MaybeNull] out object o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(19, 17),
// (20,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// D2 x8 = bool (out object? o) => throw null!; // 6
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool (out object? o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(20, 17),
// (22,17): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 x9 = bool ([MaybeNullWhen(true)] out object o) => throw null!; // 7
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool ([MaybeNullWhen(true)] out object o) =>").WithArguments("o", "lambda expression", "D3").WithLocation(22, 17),
// (24,18): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 x11 = bool ([MaybeNull] out object o) => throw null!; // 8
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool ([MaybeNull] out object o) =>").WithArguments("o", "lambda expression", "D3").WithLocation(24, 18),
// (25,18): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 x12 = bool (out object? o) => throw null!; // 9
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "bool (out object? o) =>").WithArguments("o", "lambda expression", "D3").WithLocation(25, 18)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_AnonymousFunctionConversion_NotNullIfNotNull()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate object? D1(object? o);
[return: NotNullIfNotNull(""o"")] delegate object? D2(object? o);
[return: NotNull] delegate object? D3(object? o);
[return: NotNullIfNotNull(""o"")] delegate object D4(object? o);
class Program
{
static void Main()
{
Func<object?, object> f1 = [return: NotNullIfNotNull(""o"")] (object? o) => null; // 1
D1 f2 = [return: NotNullIfNotNull(""o"")] (object? o) => null;
D2 f3 = [return: NotNullIfNotNull(""o"")] (object? o) => null;
D3 f4 = [return: NotNullIfNotNull(""o"")] (object? o) => null; // 2
D4 f5 = [return: NotNullIfNotNull(""o"")] (object? o) => null; // 3
}
}";
var comp = CreateCompilation(new[] { source, NotNullIfNotNullAttributeDefinition, NotNullAttributeDefinition });
comp.VerifyDiagnostics(
// (14,83): warning CS8603: Possible null reference return.
// Func<object?, object> f1 = [return: NotNullIfNotNull("o")] (object? o) => null; // 1
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(14, 83),
// (17,17): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// D3 f4 = [return: NotNullIfNotNull("o")] (object? o) => null; // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, @"[return: NotNullIfNotNull(""o"")] (object? o) =>").WithArguments("lambda expression", "D3").WithLocation(17, 17),
// (18,64): warning CS8603: Possible null reference return.
// D4 f5 = [return: NotNullIfNotNull("o")] (object? o) => null; // 3
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "null").WithLocation(18, 64)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_DelegateCreation_Parameter()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
delegate void D1(object o);
delegate void D2([AllowNull] object o);
delegate void D3([DisallowNull] object? o);
class Program
{
static void Main()
{
_ = new Action<object>(([AllowNull] object o) => { }); // 1
_ = new D1(([AllowNull] object o) => { }); // 2
_ = new D2(([AllowNull] object o) => { });
_ = new D3(([AllowNull] object o) => { }); // 3
_ = new Action<object>(([DisallowNull] object o) => { });
_ = new D1(([DisallowNull] object o) => { });
_ = new D2(([DisallowNull] object o) => { }); // 4
_ = new D3(([DisallowNull] object o) => { });
_ = new Action<object?>(([DisallowNull] object? o) => { }); // 5
_ = new D1(([DisallowNull] object? o) => { });
_ = new D2(([DisallowNull] object? o) => { }); // 6
_ = new D3(([DisallowNull] object? o) => { });
}
}";
var comp = CreateCompilation(new[] { source, AllowNullAttributeDefinition, DisallowNullAttributeDefinition });
comp.VerifyDiagnostics(
// (13,32): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'Action<object>' (possibly because of nullability attributes).
// _ = new Action<object>(([AllowNull] object o) => { }); // 1
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] object o) =>").WithArguments("o", "lambda expression", "System.Action<object>").WithLocation(13, 32),
// (14,20): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D1' (possibly because of nullability attributes).
// _ = new D1(([AllowNull] object o) => { }); // 2
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] object o) =>").WithArguments("o", "lambda expression", "D1").WithLocation(14, 20),
// (16,20): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D3' (possibly because of nullability attributes).
// _ = new D3(([AllowNull] object o) => { }); // 3
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] object o) =>").WithArguments("o", "lambda expression", "D3").WithLocation(16, 20),
// (20,20): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// _ = new D2(([DisallowNull] object o) => { }); // 4
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] object o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(20, 20),
// (23,33): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'Action<object?>' (possibly because of nullability attributes).
// _ = new Action<object?>(([DisallowNull] object? o) => { }); // 5
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] object? o) =>").WithArguments("o", "lambda expression", "System.Action<object?>").WithLocation(23, 33),
// (25,20): warning CS8622: Nullability of reference types in type of parameter 'o' of 'lambda expression' doesn't match the target delegate 'D2' (possibly because of nullability attributes).
// _ = new D2(([DisallowNull] object? o) => { }); // 6
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] object? o) =>").WithArguments("o", "lambda expression", "D2").WithLocation(25, 20)
);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_NullableAttributes_03()
{
var source =
@"#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
class Program
{
static void Main()
{
Action<object> a1 = ([AllowNull] x) => { x.ToString(); };
Action<object?> a2 = ([DisallowNull] x) => { x.ToString(); };
}
}";
var comp = CreateCompilation(new[] { source, AllowNullAttributeDefinition, DisallowNullAttributeDefinition }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,29): warning CS8622: Nullability of reference types in type of parameter 'x' of 'lambda expression' doesn't match the target delegate 'Action<object>' (possibly because of nullability attributes).
// Action<object> a1 = ([AllowNull] x) => { x.ToString(); };
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([AllowNull] x) =>").WithArguments("x", "lambda expression", "System.Action<object>").WithLocation(8, 29),
// (8,50): warning CS8602: Dereference of a possibly null reference.
// Action<object> a1 = ([AllowNull] x) => { x.ToString(); };
Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "x").WithLocation(8, 50),
// (9,30): warning CS8622: Nullability of reference types in type of parameter 'x' of 'lambda expression' doesn't match the target delegate 'Action<object?>' (possibly because of nullability attributes).
// Action<object?> a2 = ([DisallowNull] x) => { x.ToString(); };
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([DisallowNull] x) =>").WithArguments("x", "lambda expression", "System.Action<object?>").WithLocation(9, 30)
);
}
[WorkItem(55013, "https://github.com/dotnet/roslyn/issues/55013")]
[Fact]
public void NullableTypeArraySwitchPattern()
{
var source =
@"#nullable enable
class C
{
object? field;
string Prop => @field switch
{
string?[] a => ""a""
};
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (4,13): warning CS0649: Field 'C.field' is never assigned to, and will always have its default value null
// object? field;
Diagnostic(ErrorCode.WRN_UnassignedInternalField, "field").WithArguments("C.field", "null").WithLocation(4, 13),
// (5,27): warning CS8509: The switch expression does not handle all possible values of its input type (it is not exhaustive). For example, the pattern '_' is not covered.
// string Prop => @field switch
Diagnostic(ErrorCode.WRN_SwitchExpressionNotExhaustive, "switch").WithArguments("_").WithLocation(5, 27));
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
public void LambdaAttributes_DoesNotReturn()
{
var source = @"
#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
class Program
{
static void Main()
{
Action a1 = [DoesNotReturn] () => { };
Action a2 = [DoesNotReturn] () => throw new Exception();
}
}";
var comp = CreateCompilation(new[] { source, DoesNotReturnAttributeDefinition });
comp.VerifyDiagnostics(
// (9,43): warning CS8763: A method marked [DoesNotReturn] should not return.
// Action a1 = [DoesNotReturn] () => { };
Diagnostic(ErrorCode.WRN_ShouldNotReturn, "{ }").WithLocation(9, 43)
);
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
Assert.Equal(2, exprs.Length);
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.Equal(FlowAnalysisAnnotations.DoesNotReturn, lambdas[0].FlowAnalysisAnnotations);
Assert.Equal(FlowAnalysisAnnotations.DoesNotReturn, lambdas[1].FlowAnalysisAnnotations);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaAttributes_DoesNotReturn_OnDelegateType()
{
var source = @"
#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
[return: DoesNotReturn] delegate void DoesNotReturnDelegate();
class Program
{
static void Main()
{
DoesNotReturnDelegate a1 = [DoesNotReturn] () => { }; // 1
DoesNotReturnDelegate a2 = [DoesNotReturn] () => throw new Exception();
DoesNotReturnDelegate a3 = () => { };
DoesNotReturnDelegate a4 = () => throw new Exception();
}
}";
var comp = CreateCompilation(new[] { source, DoesNotReturnAttributeDefinition });
comp.VerifyDiagnostics(
// (6,10): error CS0592: Attribute 'DoesNotReturn' is not valid on this declaration type. It is only valid on 'method' declarations.
// [return: DoesNotReturn] delegate void DoesNotReturnDelegate();
Diagnostic(ErrorCode.ERR_AttributeOnBadSymbolType, "DoesNotReturn").WithArguments("DoesNotReturn", "method").WithLocation(6, 10),
// (6,39): warning CS8770: Method 'void DoesNotReturnDelegate.Invoke()' lacks `[DoesNotReturn]` annotation to match implemented or overridden member.
// [return: DoesNotReturn] delegate void DoesNotReturnDelegate();
Diagnostic(ErrorCode.WRN_DoesNotReturnMismatch, "DoesNotReturnDelegate").WithArguments("void DoesNotReturnDelegate.Invoke()").WithLocation(6, 39),
// (6,39): warning CS8770: Method 'void DoesNotReturnDelegate.Invoke()' lacks `[DoesNotReturn]` annotation to match implemented or overridden member.
// [return: DoesNotReturn] delegate void DoesNotReturnDelegate();
Diagnostic(ErrorCode.WRN_DoesNotReturnMismatch, "DoesNotReturnDelegate").WithArguments("void DoesNotReturnDelegate.Invoke()").WithLocation(6, 39),
// (11,58): warning CS8763: A method marked [DoesNotReturn] should not return.
// DoesNotReturnDelegate a1 = [DoesNotReturn] () => { }; // 1
Diagnostic(ErrorCode.WRN_ShouldNotReturn, "{ }").WithLocation(11, 58)
);
}
[Fact]
public void LambdaAttributes_UnmanagedCallersOnly()
{
var source =
@"using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
Action a = [UnmanagedCallersOnly] static () => { };
}
}";
var comp = CreateCompilation(new[] { source, UnmanagedCallersOnlyAttributeDefinition }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,21): error CS8896: 'UnmanagedCallersOnly' can only be applied to ordinary static non-abstract, non-virtual methods or static local functions.
// Action a = [UnmanagedCallersOnly] static () => { };
Diagnostic(ErrorCode.ERR_UnmanagedCallersOnlyRequiresStatic, "UnmanagedCallersOnly").WithLocation(7, 21));
}
[Fact]
public void LambdaParameterAttributes_OptionalAndDefaultValueAttributes()
{
var source =
@"using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
Action<int> a1 = ([Optional, DefaultParameterValue(2)] int i) => { };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,68): warning CS9099: Parameter 1 has default value '2' in lambda but '<missing>' in the target delegate type.
// Action<int> a1 = ([Optional, DefaultParameterValue(2)] int i) => { };
Diagnostic(ErrorCode.WRN_OptionalParamValueMismatch, "i").WithArguments("1", "2", "<missing>").WithLocation(7, 68));
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
var lambda = exprs.SelectAsArray(e => GetLambdaSymbol(model, e)).Single();
var parameter = (SourceParameterSymbol)lambda.Parameters[0];
Assert.True(parameter.HasOptionalAttribute);
Assert.True(parameter.HasExplicitDefaultValue);
Assert.Equal(2, parameter.DefaultValueFromAttributes.Value);
}
[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/66060")]
public void LambdaParameterAttributes_OverloadResolution()
{
var source = """
using System.Runtime.InteropServices;
new C().M(([Optional] int x = 1) => x);
new C().M((int x = 1) => x);
class C
{
public void M(D1 d) { }
public void M(D2 d) { }
}
delegate int D1(int x = 1);
delegate int D2([Optional, DefaultParameterValue(1)] int x);
""";
CreateCompilation(source).VerifyDiagnostics(
// (3,9): error CS0121: The call is ambiguous between the following methods or properties: 'C.M(D1)' and 'C.M(D2)'
// new C().M(([Optional] int x = 1) => x);
Diagnostic(ErrorCode.ERR_AmbigCall, "M").WithArguments("C.M(D1)", "C.M(D2)").WithLocation(3, 9),
// (4,9): error CS0121: The call is ambiguous between the following methods or properties: 'C.M(D1)' and 'C.M(D2)'
// new C().M((int x = 1) => x);
Diagnostic(ErrorCode.ERR_AmbigCall, "M").WithArguments("C.M(D1)", "C.M(D2)").WithLocation(4, 9));
}
[Fact]
public void LambdaParameterAttributes_OptionalAndDateTimeConstantAttributes()
{
var source =
@"using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
var lam = ([Optional, DateTimeConstant(638004778421967416L)] DateTime d) => d;
Console.Write(lam().Ticks);
}
}";
var comp = CreateCompilation(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: "638004778421967416").VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
var lambda = exprs.SelectAsArray(e => GetLambdaSymbol(model, e)).Single();
var parameter = (SourceParameterSymbol)lambda.Parameters[0];
Assert.True(parameter.HasOptionalAttribute);
Assert.True(parameter.HasExplicitDefaultValue);
Assert.Equal(new DateTime(638004778421967416L), parameter.DefaultValueFromAttributes.Value);
}
[ConditionalFact(typeof(DesktopOnly))]
public void LambdaParameterAttributes_WellKnownAttributes()
{
var source =
@"using System;
using System.Runtime.CompilerServices;
class Program
{
static void Main()
{
Action<object> a1 = ([IDispatchConstant] object obj) => { };
Action<object> a2 = ([IUnknownConstant] object obj) => { };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
Assert.Equal(2, exprs.Length);
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.True(lambdas[0].Parameters[0].IsIDispatchConstant);
Assert.True(lambdas[1].Parameters[0].IsIUnknownConstant);
}
[Fact]
public void LambdaParameterAttributes_NullableAttributes_01()
{
var source =
@"using System;
using System.Diagnostics.CodeAnalysis;
class Program
{
static void Main()
{
Action<object> a1 = ([AllowNull][MaybeNullWhen(false)] object obj) => { };
Action<object, object> a2 = (object x, [NotNullIfNotNull(""x"")] object y) => { };
}
}";
var comp = CreateCompilation(
new[] { source, AllowNullAttributeDefinition, MaybeNullWhenAttributeDefinition, NotNullIfNotNullAttributeDefinition },
parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
Assert.Equal(2, exprs.Length);
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.Equal(FlowAnalysisAnnotations.AllowNull | FlowAnalysisAnnotations.MaybeNullWhenFalse, lambdas[0].Parameters[0].FlowAnalysisAnnotations);
Assert.Equal(new[] { "x" }, lambdas[1].Parameters[1].NotNullIfParameterNotNull);
}
[Fact, WorkItem(52827, "https://github.com/dotnet/roslyn/issues/52827")]
[WorkItem(56668, "https://github.com/dotnet/roslyn/issues/56668")]
public void LambdaParameterAttributes_NullableAttributes_02()
{
var source =
@"#nullable enable
using System.Diagnostics.CodeAnalysis;
delegate bool D(out object? obj);
delegate bool D2([NotNullWhen(true)] out object? obj);
class Program
{
static void Main()
{
D d = ([NotNullWhen(true)] out object? obj) =>
{
obj = null;
return true;
};
D2 d2 = ([NotNullWhen(true)] out object? obj) =>
{
obj = null;
return false;
};
}
}";
var comp = CreateCompilation(new[] { source, NotNullWhenAttributeDefinition }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (10,15): warning CS8622: Nullability of reference types in type of parameter 'obj' of 'lambda expression' doesn't match the target delegate 'D' (possibly because of nullability attributes).
// D d = ([NotNullWhen(true)] out object? obj) =>
Diagnostic(ErrorCode.WRN_NullabilityMismatchInParameterTypeOfTargetDelegate, "([NotNullWhen(true)] out object? obj) =>").WithArguments("obj", "lambda expression", "D").WithLocation(10, 15),
// (13,17): warning CS8762: Parameter 'obj' must have a non-null value when exiting with 'true'.
// return true;
Diagnostic(ErrorCode.WRN_ParameterConditionallyDisallowsNull, "return true;").WithArguments("obj", "true").WithLocation(13, 17)
);
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var expr = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().First();
var lambda = GetLambdaSymbol(model, expr);
Assert.Equal(FlowAnalysisAnnotations.NotNullWhenTrue, lambda.Parameters[0].FlowAnalysisAnnotations);
}
[Fact]
public void LambdaReturnType_01()
{
var source =
@"using System;
class Program
{
static void F<T>()
{
Func<T> f1 = T () => default;
Func<T, T> f2 = T (x) => { return x; };
Func<T, T> f3 = T (T x) => x;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (6,22): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// Func<T> f1 = T () => default;
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "T").WithArguments("lambda return type", "10.0").WithLocation(6, 22),
// (7,25): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// Func<T, T> f2 = T (x) => { return x; };
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "T").WithArguments("lambda return type", "10.0").WithLocation(7, 25),
// (8,25): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// Func<T, T> f3 = T (T x) => x;
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "T").WithArguments("lambda return type", "10.0").WithLocation(8, 25));
comp = CreateCompilation(source, parseOptions: TestOptions.Regular10);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaReturnType_02()
{
var source =
@"using System;
class Program
{
static void F<T, U>()
{
Func<T> f1;
Func<U> f2;
f1 = T () => default;
f2 = T () => default;
f1 = U () => default;
f2 = U () => default;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (9,19): error CS8934: Cannot convert lambda expression to type 'Func<U>' because the return type does not match the delegate return type
// f2 = T () => default;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Func<U>").WithLocation(9, 19),
// (10,19): error CS8934: Cannot convert lambda expression to type 'Func<T>' because the return type does not match the delegate return type
// f1 = U () => default;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Func<T>").WithLocation(10, 19));
}
[Fact]
public void LambdaReturnType_03()
{
var source =
@"using System;
class Program
{
static void F<T, U>() where U : T
{
Func<T> f1;
Func<U> f2;
f1 = T () => default;
f2 = T () => default;
f1 = U () => default;
f2 = U () => default;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (9,19): error CS8934: Cannot convert lambda expression to type 'Func<U>' because the return type does not match the delegate return type
// f2 = T () => default;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Func<U>").WithLocation(9, 19),
// (10,19): error CS8934: Cannot convert lambda expression to type 'Func<T>' because the return type does not match the delegate return type
// f1 = U () => default;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Func<T>").WithLocation(10, 19));
}
[Fact]
public void LambdaReturnType_04()
{
var source =
@"using System;
using System.Linq.Expressions;
class Program
{
static void F<T, U>()
{
Expression<Func<T>> e1;
Expression<Func<U>> e2;
e1 = T () => default;
e2 = T () => default;
e1 = U () => default;
e2 = U () => default;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (10,19): error CS8934: Cannot convert lambda expression to type 'Expression<Func<U>>' because the return type does not match the delegate return type
// e2 = T () => default;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Linq.Expressions.Expression<System.Func<U>>").WithLocation(10, 19),
// (11,19): error CS8934: Cannot convert lambda expression to type 'Expression<Func<T>>' because the return type does not match the delegate return type
// e1 = U () => default;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Linq.Expressions.Expression<System.Func<T>>").WithLocation(11, 19));
}
[Fact]
public void LambdaReturnType_05()
{
var source =
@"#nullable enable
using System;
class Program
{
static void Main()
{
Func<dynamic> f1 = object () => default!;
Func<(int, int)> f2 = (int X, int Y) () => default;
Func<string?> f3 = string () => default!;
Func<IntPtr> f4 = nint () => default;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (9,28): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<string?>' (possibly because of nullability attributes).
// Func<string?> f3 = string () => default!;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "string () =>").WithArguments("lambda expression", "System.Func<string?>").WithLocation(9, 28));
}
[Fact]
public void LambdaReturnType_06()
{
var source =
@"#nullable enable
using System;
using System.Linq.Expressions;
class Program
{
static void Main()
{
Expression<Func<object>> e1 = dynamic () => default!;
Expression<Func<(int X, int Y)>> e2 = (int, int) () => default;
Expression<Func<string>> e3 = string? () => default;
Expression<Func<nint>> e4 = IntPtr () => default;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (10,39): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<string>' (possibly because of nullability attributes).
// Expression<Func<string>> e3 = string? () => default;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "string? () =>").WithArguments("lambda expression", "System.Func<string>").WithLocation(10, 39));
}
[Fact]
public void LambdaReturnType_07()
{
var source =
@"#nullable enable
using System;
struct S<T> { }
class Program
{
static void Main()
{
Delegate d1 = string? () => default;
Delegate d2 = string () => default;
Delegate d3 = S<object?> () => default(S<object?>);
Delegate d4 = S<object?> () => default(S<object>);
Delegate d5 = S<object> () => default(S<object?>);
Delegate d6 = S<object> () => default(S<object>);
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (9,36): warning CS8603: Possible null reference return.
// Delegate d2 = string () => default;
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "default").WithLocation(9, 36),
// (11,40): warning CS8619: Nullability of reference types in value of type 'S<object>' doesn't match target type 'S<object?>'.
// Delegate d4 = S<object?> () => default(S<object>);
Diagnostic(ErrorCode.WRN_NullabilityMismatchInAssignment, "default(S<object>)").WithArguments("S<object>", "S<object?>").WithLocation(11, 40),
// (12,39): warning CS8619: Nullability of reference types in value of type 'S<object?>' doesn't match target type 'S<object>'.
// Delegate d5 = S<object> () => default(S<object?>);
Diagnostic(ErrorCode.WRN_NullabilityMismatchInAssignment, "default(S<object?>)").WithArguments("S<object?>", "S<object>").WithLocation(12, 39));
}
[Fact]
public void LambdaReturnType_08()
{
var source =
@"#nullable enable
using System;
struct S<T> { }
class Program
{
static void Main()
{
Func<string?> f1 = string? () => throw null!;
Func<string?> f2 = string () => throw null!;
Func<string> f3 = string? () => throw null!;
Func<string> f4 = string () => throw null!;
Func<S<object?>> f5 = S<object?> () => throw null!;
Func<S<object?>> f6 = S<object> () => throw null!;
Func<S<object>> f7 = S<object?> () => throw null!;
Func<S<object>> f8 = S<object> () => throw null!;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (9,28): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<string?>' (possibly because of nullability attributes).
// Func<string?> f2 = string () => throw null!;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "string () =>").WithArguments("lambda expression", "System.Func<string?>").WithLocation(9, 28),
// (10,27): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<string>' (possibly because of nullability attributes).
// Func<string> f3 = string? () => throw null!;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "string? () =>").WithArguments("lambda expression", "System.Func<string>").WithLocation(10, 27),
// (13,31): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<S<object?>>' (possibly because of nullability attributes).
// Func<S<object?>> f6 = S<object> () => throw null!;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "S<object> () =>").WithArguments("lambda expression", "System.Func<S<object?>>").WithLocation(13, 31),
// (14,30): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<S<object>>' (possibly because of nullability attributes).
// Func<S<object>> f7 = S<object?> () => throw null!;
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "S<object?> () =>").WithArguments("lambda expression", "System.Func<S<object>>").WithLocation(14, 30));
}
[Fact]
public void LambdaReturnType_09()
{
var source =
@"#nullable enable
struct S<T> { }
delegate ref T D1<T>();
delegate ref readonly T D2<T>();
class Program
{
static void Main()
{
D1<S<object?>> f1 = (ref S<object?> () => throw null!);
D1<S<object?>> f2 = (ref S<object> () => throw null!);
D1<S<object>> f3 = (ref S<object?> () => throw null!);
D1<S<object>> f4 = (ref S<object> () => throw null!);
D2<S<object?>> f5 = (ref readonly S<object?> () => throw null!);
D2<S<object?>> f6 = (ref readonly S<object> () => throw null!);
D2<S<object>> f7 = (ref readonly S<object?> () => throw null!);
D2<S<object>> f8 = (ref readonly S<object> () => throw null!);
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (10,30): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D1<S<object?>>' (possibly because of nullability attributes).
// D1<S<object?>> f2 = (ref S<object> () => throw null!);
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "ref S<object> () =>").WithArguments("lambda expression", "D1<S<object?>>").WithLocation(10, 30),
// (11,29): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D1<S<object>>' (possibly because of nullability attributes).
// D1<S<object>> f3 = (ref S<object?> () => throw null!);
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "ref S<object?> () =>").WithArguments("lambda expression", "D1<S<object>>").WithLocation(11, 29),
// (14,30): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D2<S<object?>>' (possibly because of nullability attributes).
// D2<S<object?>> f6 = (ref readonly S<object> () => throw null!);
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "ref readonly S<object> () =>").WithArguments("lambda expression", "D2<S<object?>>").WithLocation(14, 30),
// (15,29): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'D2<S<object>>' (possibly because of nullability attributes).
// D2<S<object>> f7 = (ref readonly S<object?> () => throw null!);
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "ref readonly S<object?> () =>").WithArguments("lambda expression", "D2<S<object>>").WithLocation(15, 29));
}
[Fact]
public void LambdaReturnType_10()
{
var source =
@"delegate T D1<T>(ref T t);
delegate ref T D2<T>(ref T t);
delegate ref readonly T D3<T>(ref T t);
class Program
{
static void F<T>()
{
D1<T> d1;
D2<T> d2;
D3<T> d3;
d1 = T (ref T t) => t;
d2 = T (ref T t) => t;
d3 = T (ref T t) => t;
d1 = (ref T (ref T t) => ref t);
d2 = (ref T (ref T t) => ref t);
d3 = (ref T (ref T t) => ref t);
d1 = (ref readonly T (ref T t) => ref t);
d2 = (ref readonly T (ref T t) => ref t);
d3 = (ref readonly T (ref T t) => ref t);
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (12,26): error CS8934: Cannot convert lambda expression to type 'D2<T>' because the return type does not match the delegate return type
// d2 = T (ref T t) => t;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "D2<T>").WithLocation(12, 26),
// (13,26): error CS8934: Cannot convert lambda expression to type 'D3<T>' because the return type does not match the delegate return type
// d3 = T (ref T t) => t;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "D3<T>").WithLocation(13, 26),
// (14,31): error CS8934: Cannot convert lambda expression to type 'D1<T>' because the return type does not match the delegate return type
// d1 = (ref T (ref T t) => ref t);
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "D1<T>").WithLocation(14, 31),
// (16,31): error CS8934: Cannot convert lambda expression to type 'D3<T>' because the return type does not match the delegate return type
// d3 = (ref T (ref T t) => ref t);
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "D3<T>").WithLocation(16, 31),
// (17,40): error CS8934: Cannot convert lambda expression to type 'D1<T>' because the return type does not match the delegate return type
// d1 = (ref readonly T (ref T t) => ref t);
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "D1<T>").WithLocation(17, 40),
// (18,40): error CS8934: Cannot convert lambda expression to type 'D2<T>' because the return type does not match the delegate return type
// d2 = (ref readonly T (ref T t) => ref t);
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "D2<T>").WithLocation(18, 40));
}
[Fact]
public void LambdaReturnType_11()
{
var source =
@"using System;
class Program
{
static void Main()
{
Delegate d;
d = (ref void () => { });
d = (ref readonly void () => { });
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,18): error CS1547: Keyword 'void' cannot be used in this context
// d = (ref void () => { });
Diagnostic(ErrorCode.ERR_NoVoidHere, "void").WithLocation(7, 18),
// (8,27): error CS1547: Keyword 'void' cannot be used in this context
// d = (ref readonly void () => { });
Diagnostic(ErrorCode.ERR_NoVoidHere, "void").WithLocation(8, 27));
}
[WorkItem(55217, "https://github.com/dotnet/roslyn/issues/55217")]
[ConditionalFact(typeof(DesktopOnly))]
public void LambdaReturnType_12()
{
var source =
@"using System;
class Program
{
static void Main()
{
Delegate d;
d = TypedReference () => throw null;
d = RuntimeArgumentHandle () => throw null;
d = ArgIterator () => throw null;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,13): error CS1599: The return type of a method, delegate, or function pointer cannot be 'TypedReference'
// d = TypedReference () => throw null;
Diagnostic(ErrorCode.ERR_MethodReturnCantBeRefAny, "TypedReference").WithArguments("System.TypedReference").WithLocation(7, 13),
// (8,13): error CS1599: The return type of a method, delegate, or function pointer cannot be 'RuntimeArgumentHandle'
// d = RuntimeArgumentHandle () => throw null;
Diagnostic(ErrorCode.ERR_MethodReturnCantBeRefAny, "RuntimeArgumentHandle").WithArguments("System.RuntimeArgumentHandle").WithLocation(8, 13),
// (9,13): error CS1599: The return type of a method, delegate, or function pointer cannot be 'ArgIterator'
// d = ArgIterator () => throw null;
Diagnostic(ErrorCode.ERR_MethodReturnCantBeRefAny, "ArgIterator").WithArguments("System.ArgIterator").WithLocation(9, 13));
}
[Fact]
public void LambdaReturnType_13()
{
var source =
@"static class S { }
delegate S D();
class Program
{
static void Main()
{
D d = S () => default;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,15): error CS0722: 'S': static types cannot be used as return types
// D d = S () => default;
Diagnostic(ErrorCode.ERR_ReturnTypeIsStaticClass, "S").WithArguments("S").WithLocation(7, 15));
}
[Fact]
public void LambdaReturnType_14()
{
var source =
@"using System;
class Program
{
static void Main()
{
Delegate d = async int () => 0;
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (6,35): error CS1983: The return type of an async method must be void, Task, Task<T>, a task-like type, IAsyncEnumerable<T>, or IAsyncEnumerator<T>
// Delegate d = async int () => 0;
Diagnostic(ErrorCode.ERR_BadAsyncReturn, "=>").WithLocation(6, 35),
// (6,35): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.
// Delegate d = async int () => 0;
Diagnostic(ErrorCode.WRN_AsyncLacksAwaits, "=>").WithLocation(6, 35));
}
[Fact]
public void LambdaReturnType_15()
{
var source =
@"using System;
using System.Threading.Tasks;
delegate ref Task D(string s);
class Program
{
static void Main()
{
Delegate d1 = async ref Task (s) => { _ = s.Length; await Task.Yield(); };
D d2 = async ref Task (s) => { _ = s.Length; await Task.Yield(); };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,29): error CS1073: Unexpected token 'ref'
// Delegate d1 = async ref Task (s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_UnexpectedToken, "ref").WithArguments("ref").WithLocation(8, 29),
// (8,42): error CS8917: The delegate type could not be inferred.
// Delegate d1 = async ref Task (s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_CannotInferDelegateType, "=>").WithLocation(8, 42),
// (9,22): error CS1073: Unexpected token 'ref'
// D d2 = async ref Task (s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_UnexpectedToken, "ref").WithArguments("ref").WithLocation(9, 22));
}
[Fact]
public void LambdaReturnType_16()
{
var source =
@"using System;
using System.Threading.Tasks;
delegate ref Task D(string s);
class Program
{
static void Main()
{
Delegate d1 = async ref Task (string s) => { _ = s.Length; await Task.Yield(); };
D d2 = async ref Task (string s) => { _ = s.Length; await Task.Yield(); };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,29): error CS1073: Unexpected token 'ref'
// Delegate d1 = async ref Task (string s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_UnexpectedToken, "ref").WithArguments("ref").WithLocation(8, 29),
// (9,22): error CS1073: Unexpected token 'ref'
// D d2 = async ref Task (string s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_UnexpectedToken, "ref").WithArguments("ref").WithLocation(9, 22));
}
[Fact]
public void LambdaReturnType_17()
{
var source =
@"#nullable enable
using System;
class Program
{
static void F(string? x, string y)
{
Func<string?> f1 = string () => { if (x is null) return x; return y; };
Func<string> f2 = string? () => { if (x is not null) return x; return y; };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,28): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<string?>' (possibly because of nullability attributes).
// Func<string?> f1 = string () => { if (x is null) return x; return y; };
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "string () =>").WithArguments("lambda expression", "System.Func<string?>").WithLocation(7, 28),
// (7,65): warning CS8603: Possible null reference return.
// Func<string?> f1 = string () => { if (x is null) return x; return y; };
Diagnostic(ErrorCode.WRN_NullReferenceReturn, "x").WithLocation(7, 65),
// (8,27): warning CS8621: Nullability of reference types in return type of 'lambda expression' doesn't match the target delegate 'Func<string>' (possibly because of nullability attributes).
// Func<string> f2 = string? () => { if (x is not null) return x; return y; };
Diagnostic(ErrorCode.WRN_NullabilityMismatchInReturnTypeOfTargetDelegate, "string? () =>").WithArguments("lambda expression", "System.Func<string>").WithLocation(8, 27));
}
[Fact]
public void LambdaReturnType_18()
{
var source =
@"using System;
class Program
{
static void F<T, U, V>(T t, U u, V v) where U : T
{
Func<T> f1 = T () => u;
Func<T> f2 = T () => v;
Func<U> f3 = U () => t;
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,30): error CS0029: Cannot implicitly convert type 'V' to 'T'
// Func<T> f2 = T () => v;
Diagnostic(ErrorCode.ERR_NoImplicitConv, "v").WithArguments("V", "T").WithLocation(7, 30),
// (7,30): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<T> f2 = T () => v;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "v").WithArguments("lambda expression").WithLocation(7, 30),
// (8,30): error CS0266: Cannot implicitly convert type 'T' to 'U'. An explicit conversion exists (are you missing a cast?)
// Func<U> f3 = U () => t;
Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "t").WithArguments("T", "U").WithLocation(8, 30),
// (8,30): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<U> f3 = U () => t;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "t").WithArguments("lambda expression").WithLocation(8, 30));
}
[Fact]
public void LambdaReturnType_19()
{
var source =
@"using System;
class Program
{
static void F<T, U, V>(T t, U u, V v) where U : T
{
Delegate d;
d = T () => u;
d = T () => v;
d = U () => t;
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (8,21): error CS0029: Cannot implicitly convert type 'V' to 'T'
// d = T () => v;
Diagnostic(ErrorCode.ERR_NoImplicitConv, "v").WithArguments("V", "T").WithLocation(8, 21),
// (8,21): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// d = T () => v;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "v").WithArguments("lambda expression").WithLocation(8, 21),
// (9,21): error CS0266: Cannot implicitly convert type 'T' to 'U'. An explicit conversion exists (are you missing a cast?)
// d = U () => t;
Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "t").WithArguments("T", "U").WithLocation(9, 21),
// (9,21): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// d = U () => t;
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "t").WithArguments("lambda expression").WithLocation(9, 21));
}
[Fact]
public void LambdaReturnType_20()
{
var source =
@"using System;
class Program
{
static void F<T, U, V>(T t, U u, V v) where U : T
{
Func<T> f1 = T () => { if (t is null) return t; return u; };
Func<U> f2 = U () => { if (t is null) return t; return u; };
Func<T> f3 = T () => { if (t is null) return t; return v; };
Func<V> f4 = V () => { if (t is null) return t; return v; };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,54): error CS0266: Cannot implicitly convert type 'T' to 'U'. An explicit conversion exists (are you missing a cast?)
// Func<U> f2 = U () => { if (t is null) return t; return u; };
Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "t").WithArguments("T", "U").WithLocation(7, 54),
// (7,54): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<U> f2 = U () => { if (t is null) return t; return u; };
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "t").WithArguments("lambda expression").WithLocation(7, 54),
// (8,64): error CS0029: Cannot implicitly convert type 'V' to 'T'
// Func<T> f3 = T () => { if (t is null) return t; return v; };
Diagnostic(ErrorCode.ERR_NoImplicitConv, "v").WithArguments("V", "T").WithLocation(8, 64),
// (8,64): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<T> f3 = T () => { if (t is null) return t; return v; };
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "v").WithArguments("lambda expression").WithLocation(8, 64),
// (9,54): error CS0029: Cannot implicitly convert type 'T' to 'V'
// Func<V> f4 = V () => { if (t is null) return t; return v; };
Diagnostic(ErrorCode.ERR_NoImplicitConv, "t").WithArguments("T", "V").WithLocation(9, 54),
// (9,54): error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
// Func<V> f4 = V () => { if (t is null) return t; return v; };
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturns, "t").WithArguments("lambda expression").WithLocation(9, 54));
}
[Fact]
public void LambdaReturnType_SemanticModel()
{
var source =
@"class Program
{
static void F<T>()
{
var x = T () => default;
}
}";
var comp = CreateCompilation(source);
comp.VerifyEmitDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var lambdaSyntax = tree.GetRoot().DescendantNodes().OfType<ParenthesizedLambdaExpressionSyntax>().Single();
var expectedType = comp.GetMember<MethodSymbol>("Program.F").TypeParameters.Single().GetPublicSymbol();
Assert.Equal(TypeKind.TypeParameter, expectedType.TypeKind);
Assert.Equal("T", expectedType.ToTestDisplayString());
var method = (IMethodSymbol)model.GetSymbolInfo(lambdaSyntax).Symbol;
Assert.Equal(MethodKind.LambdaMethod, method.MethodKind);
var returnTypeSyntax = lambdaSyntax.ReturnType;
var typeInfo = model.GetTypeInfo(returnTypeSyntax);
Assert.Equal(expectedType, typeInfo.Type);
Assert.Equal(expectedType, typeInfo.ConvertedType);
var symbolInfo = model.GetSymbolInfo(returnTypeSyntax);
Assert.Equal(expectedType, symbolInfo.Symbol);
}
[Fact]
public void LambdaReturnType_CustomModifiers_01()
{
var sourceA =
@".class public auto ansi sealed D extends [mscorlib]System.MulticastDelegate
{
.method public hidebysig specialname rtspecialname instance void .ctor (object 'object', native int 'method') runtime managed { }
.method public hidebysig newslot virtual instance int32 modopt([mscorlib]System.Int16) Invoke () runtime managed { }
.method public hidebysig newslot virtual instance class [mscorlib]System.IAsyncResult BeginInvoke (class [mscorlib]System.AsyncCallback callback, object 'object') runtime managed { }
.method public hidebysig newslot virtual instance int32 modopt([mscorlib]System.Int16) EndInvoke (class [mscorlib]System.IAsyncResult result) runtime managed { }
}";
var refA = CompileIL(sourceA);
var sourceB =
@"class Program
{
static void F(D d)
{
System.Console.WriteLine(d());
}
static void Main()
{
F(() => 1);
F(int () => 2);
}
}";
CompileAndVerify(sourceB, references: new[] { refA }, parseOptions: TestOptions.RegularPreview, expectedOutput:
@"1
2");
}
[Fact]
public void LambdaReturnType_CustomModifiers_02()
{
var sourceA =
@".class public auto ansi sealed D extends [mscorlib]System.MulticastDelegate
{
.method public hidebysig specialname rtspecialname instance void .ctor (object 'object', native int 'method') runtime managed { }
.method public hidebysig newslot virtual instance int32 modreq([mscorlib]System.Int16) Invoke () runtime managed { }
.method public hidebysig newslot virtual instance class [mscorlib]System.IAsyncResult BeginInvoke (class [mscorlib]System.AsyncCallback callback, object 'object') runtime managed { }
.method public hidebysig newslot virtual instance int32 modreq([mscorlib]System.Int16) EndInvoke (class [mscorlib]System.IAsyncResult result) runtime managed { }
}";
var refA = CompileIL(sourceA);
var sourceB =
@"class Program
{
static void F(D d)
{
System.Console.WriteLine(d());
}
static void Main()
{
F(() => 1);
F(int () => 2);
}
}";
var comp = CreateCompilation(sourceB, references: new[] { refA }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (5,34): error CS0570: 'D.Invoke()' is not supported by the language
// System.Console.WriteLine(d());
Diagnostic(ErrorCode.ERR_BindToBogus, "d()").WithArguments("D.Invoke()").WithLocation(5, 34),
// (9,14): error CS0570: 'D.Invoke()' is not supported by the language
// F(() => 1);
Diagnostic(ErrorCode.ERR_BindToBogus, "=>").WithArguments("D.Invoke()").WithLocation(9, 14),
// (10,18): error CS0570: 'D.Invoke()' is not supported by the language
// F(int () => 2);
Diagnostic(ErrorCode.ERR_BindToBogus, "=>").WithArguments("D.Invoke()").WithLocation(10, 18));
}
[Fact]
public void LambdaReturnType_UseSiteErrors()
{
var sourceA =
@".class public sealed A extends [mscorlib]System.Object
{
.custom instance void [mscorlib]System.Runtime.CompilerServices.RequiredAttributeAttribute::.ctor(class [mscorlib]System.Type) = ( 01 00 FF 00 00 )
.method public hidebysig specialname rtspecialname instance void .ctor() cil managed { ret }
}";
var refA = CompileIL(sourceA);
var sourceB =
@"using System;
class B
{
static void F<T>(Func<T> f) { }
static void Main()
{
F(A () => default);
}
}";
var comp = CreateCompilation(sourceB, references: new[] { refA }, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (7,11): error CS0648: 'A' is a type not supported by the language
// F(A () => default);
Diagnostic(ErrorCode.ERR_BogusType, "A").WithArguments("A").WithLocation(7, 11));
}
[Fact]
public void VarReturnType_01()
{
var source =
@"using System;
class Program
{
static void Main()
{
Delegate d;
d = var () => throw null;
d = ref var () => throw null;
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,13): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// d = var () => throw null;
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(7, 13),
// (7,13): error CS0825: The contextual keyword 'var' may only appear within a local variable declaration or in script code
// d = var () => throw null;
Diagnostic(ErrorCode.ERR_TypeVarNotFound, "var").WithLocation(7, 13),
// (8,17): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// d = ref var () => throw null;
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(8, 17),
// (8,17): error CS0825: The contextual keyword 'var' may only appear within a local variable declaration or in script code
// d = ref var () => throw null;
Diagnostic(ErrorCode.ERR_TypeVarNotFound, "var").WithLocation(8, 17));
}
[Fact]
public void VarReturnType_02()
{
var source =
@"using System;
class var { }
class Program
{
static void Main()
{
Delegate d;
d = var () => default;
d = ref var (ref var v) => ref v;
d = @var () => default;
d = ref @var (ref var v) => ref v;
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (2,7): warning CS8981: The type name 'var' only contains lower-cased ascii characters. Such names may become reserved for the language.
// class var { }
Diagnostic(ErrorCode.WRN_LowerCaseTypeName, "var").WithArguments("var").WithLocation(2, 7),
// (8,13): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// d = var () => default;
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(8, 13),
// (9,17): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// d = ref var (ref var v) => ref v;
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(9, 17));
}
[Fact]
public void VarReturnType_03()
{
var source =
@"using System;
class @var { }
class Program
{
static void Main()
{
F(var () => default);
F(ref var (ref var v) => ref v);
F(@var () => default);
F(ref @var (ref var v) => ref v);
F(() => default(var));
}
static void F(Delegate d) { }
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,11): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(var () => default);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(7, 11),
// (8,15): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(ref var (ref var v) => ref v);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(8, 15));
}
[Fact]
public void VarReturnType_04()
{
var source =
@"using System;
struct @var
{
internal class @other { }
internal other o;
}
class Program
{
static void Main()
{
F(var () => default);
F(ref var () => throw null);
F(var[] () => default);
F(var? (var v) => v);
F(var.other (var v) => v.o);
}
static void F(Delegate d) { }
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (11,11): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(var () => default);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(11, 11),
// (12,15): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(ref var () => throw null);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(12, 15));
}
[Fact]
public void VarReturnType_05()
{
var source =
@"using System;
using @var = System.Int32;
class Program
{
static void Main()
{
F(var (var v) => v);
F(@var (var v) => v);
F(() => default(var));
}
static void F(Delegate d) { }
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,11): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(var (var v) => v);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(7, 11));
}
[Fact]
public void VarReturnType_06()
{
var source =
@"using System;
class Program
{
static void M<@var>()
{
F(var (var v) => v);
F(@var (var v) => v);
F(() => default(var));
}
static void F(Delegate d) { }
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (6,11): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(var () => default);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(6, 11));
}
[Fact]
public void VarReturnType_07()
{
var source =
@"using System;
static class @var { }
class Program
{
static void Main()
{
F(var () => default);
}
static void F(Delegate d) { }
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,11): error CS8975: The contextual keyword 'var' cannot be used as an explicit lambda return type
// F(var () => default);
Diagnostic(ErrorCode.ERR_LambdaExplicitReturnTypeVar, "var").WithLocation(7, 11),
// (7,11): error CS0722: 'var': static types cannot be used as return types
// F(var () => default);
Diagnostic(ErrorCode.ERR_ReturnTypeIsStaticClass, "var").WithArguments("var").WithLocation(7, 11));
}
[Fact]
public void AsyncLambdaParameters_01()
{
var source =
@"using System;
using System.Threading.Tasks;
delegate Task D(ref string s);
class Program
{
static void Main()
{
Delegate d1 = async (ref string s) => { _ = s.Length; await Task.Yield(); };
D d2 = async (ref string s) => { _ = s.Length; await Task.Yield(); };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (8,41): error CS1988: Async methods cannot have ref, in or out parameters
// Delegate d1 = async (ref string s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_BadAsyncArgType, "s").WithLocation(8, 41),
// (9,34): error CS1988: Async methods cannot have ref, in or out parameters
// D d2 = async (ref string s) => { _ = s.Length; await Task.Yield(); };
Diagnostic(ErrorCode.ERR_BadAsyncArgType, "s").WithLocation(9, 34));
}
[ConditionalFact(typeof(DesktopOnly))]
public void AsyncLambdaParameters_02()
{
var source =
@"using System;
using System.Threading.Tasks;
delegate void D1(TypedReference r);
delegate void D2(RuntimeArgumentHandle h);
delegate void D3(ArgIterator i);
class Program
{
static void Main()
{
D1 d1 = async (TypedReference r) => { await Task.Yield(); };
D2 d2 = async (RuntimeArgumentHandle h) => { await Task.Yield(); };
D3 d3 = async (ArgIterator i) => { await Task.Yield(); };
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (10,39): error CS4012: Parameters of type 'TypedReference' cannot be declared in async methods or async lambda expressions.
// D1 d1 = async (TypedReference r) => { await Task.Yield(); };
Diagnostic(ErrorCode.ERR_BadSpecialByRefParameter, "r").WithArguments("System.TypedReference").WithLocation(10, 39),
// (11,46): error CS4012: Parameters of type 'RuntimeArgumentHandle' cannot be declared in async methods or async lambda expressions.
// D2 d2 = async (RuntimeArgumentHandle h) => { await Task.Yield(); };
Diagnostic(ErrorCode.ERR_BadSpecialByRefParameter, "h").WithArguments("System.RuntimeArgumentHandle").WithLocation(11, 46),
// (12,36): error CS4012: Parameters of type 'ArgIterator' cannot be declared in async methods or async lambda expressions.
// D3 d3 = async (ArgIterator i) => { await Task.Yield(); };
Diagnostic(ErrorCode.ERR_BadSpecialByRefParameter, "i").WithArguments("System.ArgIterator").WithLocation(12, 36));
}
[Fact]
public void BestType_01()
{
var source =
@"using System;
class A { }
class B1 : A { }
class B2 : A { }
interface I { }
class C1 : I { }
class C2 : I { }
class Program
{
static void F<T>(Func<bool, T> f) { }
static void Main()
{
F((bool b) => { if (b) return new B1(); return new B2(); });
F((bool b) => { if (b) return new C1(); return new C2(); });
}
}";
var expectedDiagnostics = new[]
{
// (13,9): error CS0411: The type arguments for method 'Program.F<T>(Func<bool, T>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
// F((bool b) => { if (b) return new B1(); return new B2(); });
Diagnostic(ErrorCode.ERR_CantInferMethTypeArgs, "F").WithArguments("Program.F<T>(System.Func<bool, T>)").WithLocation(13, 9),
// (14,9): error CS0411: The type arguments for method 'Program.F<T>(Func<bool, T>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
// F((bool b) => { if (b) return new C1(); return new C2(); });
Diagnostic(ErrorCode.ERR_CantInferMethTypeArgs, "F").WithArguments("Program.F<T>(System.Func<bool, T>)").WithLocation(14, 9)
};
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(expectedDiagnostics);
comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(expectedDiagnostics);
}
// As above but with explicit return type.
[Fact]
public void BestType_02()
{
var source =
@"using System;
class A { }
class B1 : A { }
class B2 : A { }
interface I { }
class C1 : I { }
class C2 : I { }
class Program
{
static void F<T>(Func<bool, T> f) { Console.WriteLine(typeof(T)); }
static void Main()
{
F(A (bool b) => { if (b) return new B1(); return new B2(); });
F(I (bool b) => { if (b) return new C1(); return new C2(); });
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (13,11): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(A (bool b) => { if (b) return new B1(); return new B2(); });
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "A").WithArguments("lambda return type", "10.0").WithLocation(13, 11),
// (14,11): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(I (bool b) => { if (b) return new C1(); return new C2(); });
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "I").WithArguments("lambda return type", "10.0").WithLocation(14, 11));
CompileAndVerify(source, parseOptions: TestOptions.RegularPreview, expectedOutput:
@"A
I");
}
[WorkItem(54257, "https://github.com/dotnet/roslyn/issues/54257")]
[Fact]
public void BestType_03()
{
var source =
@"using System;
class A { }
class B1 : A { }
class B2 : A { }
class Program
{
static void F<T>(Func<T> x, Func<T> y) { }
static void Main()
{
F(B2 () => null, B2 () => null);
F(A () => null, B2 () => null);
F(B1 () => null, B2 () => null);
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (10,11): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(B2 () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "B2").WithArguments("lambda return type", "10.0").WithLocation(10, 11),
// (10,26): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(B2 () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "B2").WithArguments("lambda return type", "10.0").WithLocation(10, 26),
// (11,9): error CS0411: The type arguments for method 'Program.F<T>(Func<T>, Func<T>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
// F(A () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_CantInferMethTypeArgs, "F").WithArguments("Program.F<T>(System.Func<T>, System.Func<T>)").WithLocation(11, 9),
// (11,11): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(A () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "A").WithArguments("lambda return type", "10.0").WithLocation(11, 11),
// (11,25): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(A () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "B2").WithArguments("lambda return type", "10.0").WithLocation(11, 25),
// (12,9): error CS0411: The type arguments for method 'Program.F<T>(Func<T>, Func<T>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
// F(B1 () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_CantInferMethTypeArgs, "F").WithArguments("Program.F<T>(System.Func<T>, System.Func<T>)").WithLocation(12, 9),
// (12,11): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(B1 () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "B1").WithArguments("lambda return type", "10.0").WithLocation(12, 11),
// (12,26): error CS8773: Feature 'lambda return type' is not available in C# 9.0. Please use language version 10.0 or greater.
// F(B1 () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion9, "B2").WithArguments("lambda return type", "10.0").WithLocation(12, 26));
comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics(
// (11,9): error CS0411: The type arguments for method 'Program.F<T>(Func<T>, Func<T>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
// F(A () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_CantInferMethTypeArgs, "F").WithArguments("Program.F<T>(System.Func<T>, System.Func<T>)").WithLocation(11, 9),
// (12,9): error CS0411: The type arguments for method 'Program.F<T>(Func<T>, Func<T>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
// F(B1 () => null, B2 () => null);
Diagnostic(ErrorCode.ERR_CantInferMethTypeArgs, "F").WithArguments("Program.F<T>(System.Func<T>, System.Func<T>)").WithLocation(12, 9));
}
[Fact]
public void TypeInference_01()
{
var source =
@"using System;
class Program
{
static void F<T>(Func<object, T> f)
{
Console.WriteLine(typeof(T));
}
static void Main()
{
F(long (o) => 1);
}
}";
CompileAndVerify(source, parseOptions: TestOptions.RegularPreview, expectedOutput: @"System.Int64");
}
[WorkItem(54257, "https://github.com/dotnet/roslyn/issues/54257")]
[Fact]
public void TypeInference_02()
{
var source =
@"using System;
class Program
{
static void F<T>(Func<T, T> f)
{
Console.WriteLine(typeof(T));
}
static void Main()
{
F(int (i) => i);
}
}";
var comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
comp.VerifyDiagnostics();
}
// CS4031 is not reported for async lambda in [SecurityCritical] type.
[Fact]
[WorkItem(54074, "https://github.com/dotnet/roslyn/issues/54074")]
public void SecurityCritical_AsyncLambda()
{
var source =
@"using System;
using System.Security;
using System.Threading.Tasks;
[SecurityCritical]
class Program
{
static void Main()
{
Func<Task> f = async () => await Task.Yield();
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
// CS4031 is not reported for async lambda in [SecurityCritical] type.
[Fact]
[WorkItem(54074, "https://github.com/dotnet/roslyn/issues/54074")]
public void SecurityCritical_AsyncLambda_AttributeArgument()
{
var source =
@"using System;
using System.Security;
using System.Threading.Tasks;
class A : Attribute
{
internal A(int i) { }
}
[SecurityCritical]
[A(F(async () => await Task.Yield()))]
class Program
{
internal static int F(Func<Task> f) => 0;
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (9,4): error CS0182: An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type
// [A(F(async () => await Task.Yield()))]
Diagnostic(ErrorCode.ERR_BadAttributeArgument, "F(async () => await Task.Yield())").WithLocation(9, 4));
}
private static LambdaSymbol GetLambdaSymbol(SemanticModel model, LambdaExpressionSyntax syntax)
{
return model.GetSymbolInfo(syntax).Symbol.GetSymbol<LambdaSymbol>();
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_01()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [A] (x) => x;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [A] (x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[A] (x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_02()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [A][A] (x) => x;
[AttributeUsage(AttributeTargets.All, AllowMultiple = true)]
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [A][A] (x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[A][A] (x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_03()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = ([A] x) => x;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,37): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = ([A] x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "x").WithLocation(5, 37)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_04()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = ([A][A] x) => x;
[AttributeUsage(AttributeTargets.All, AllowMultiple = true)]
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,40): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = ([A][A] x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "x").WithLocation(5, 40)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_05()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int, int>> e = ([A] x, [A] y) => x + y;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,42): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int, int>> e = ([A] x, [A] y) => x + y;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "x").WithLocation(5, 42)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_06()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [return: A] (x) => x;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [return: A] (x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[return: A] (x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_07()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [return: A][return: A] (x) => x;
[AttributeUsage(AttributeTargets.All, AllowMultiple = true)]
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [return: A][return: A] (x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[return: A][return: A] (x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_08()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [A][return: A] (x) => x;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [A][return: A] (x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[A][return: A] (x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_09()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [A] ([A] x) => x;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [A] ([A] x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[A] ([A] x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(53910, "https://github.com/dotnet/roslyn/issues/53910")]
public void WithAttributesToExpressionTree_10()
{
var source =
@"
using System;
using System.Linq.Expressions;
Expression<Func<int, int>> e = [return: A] ([A] x) => x;
class A : Attribute { }
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS8972: A lambda expression with attributes cannot be converted to an expression tree
// Expression<Func<int, int>> e = [return: A] ([A] x) => x;
Diagnostic(ErrorCode.ERR_LambdaWithAttributesToExpressionTree, "[return: A] ([A] x) => x").WithLocation(5, 32)
);
}
[Fact]
[WorkItem(60661, "https://github.com/dotnet/roslyn/issues/60661")]
public void KeywordParameterName_01()
{
var source =
@"using System;
class Program
{
static void Main()
{
Action<int> a = int => { };
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (6,25): error CS1041: Identifier expected; 'int' is a keyword
// Action<int> a = int => { };
Diagnostic(ErrorCode.ERR_IdentifierExpectedKW, "int").WithArguments("", "int").WithLocation(6, 25));
}
[Fact]
[WorkItem(60661, "https://github.com/dotnet/roslyn/issues/60661")]
public void KeywordParameterName_02()
{
var source =
@"using System;
class Program
{
static void Main()
{
Action<int> a = ref => { };
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (6,25): error CS1041: Identifier expected; 'ref' is a keyword
// Action<int> a = ref => { };
Diagnostic(ErrorCode.ERR_IdentifierExpectedKW, "ref").WithArguments("", "ref").WithLocation(6, 25));
}
[Fact]
[WorkItem(60661, "https://github.com/dotnet/roslyn/issues/60661")]
public void KeywordParameterName_03()
{
var source =
@"using System;
class Program
{
static void Main()
{
Action<int> a = ref int => { };
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (6,21): error CS8171: Cannot initialize a by-value variable with a reference
// Action<int> a = ref int => { };
Diagnostic(ErrorCode.ERR_InitializeByValueVariableWithReference, "a = ref int => { }").WithLocation(6, 21),
// (6,29): error CS1041: Identifier expected; 'int' is a keyword
// Action<int> a = ref int => { };
Diagnostic(ErrorCode.ERR_IdentifierExpectedKW, "int").WithArguments("", "int").WithLocation(6, 29));
}
/// <summary>
/// Look for usages of "parameter" and verify the index-th one.
/// </summary>
private void VerifyParameter(CSharpCompilation comp, int index)
{
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var parameterUsages = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>()
.Where(i => i.Identifier.ValueText == "parameter")
.Where(i => i.Ancestors().Any(a => a.IsKind(SyntaxKind.Attribute) || a.IsKind(SyntaxKind.DefaultExpression) || a.IsKind(SyntaxKind.InvocationExpression)))
.ToArray();
var parameterUsage = parameterUsages[index];
Assert.Null(model.GetSymbolInfo(parameterUsage).Symbol);
Assert.True(model.GetTypeInfo(parameterUsage).Type.IsErrorType());
Assert.DoesNotContain("parameter", model.LookupSymbols(parameterUsage.Position).ToTestDisplayStrings());
}
[Fact]
public void ParameterScope_NotInMethodAttributeTypeOf()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ =
[My(typeof(parameter))] // 1
void(int parameter) => { };
}
[My(typeof(parameter))] // 2
void M2(int parameter) { }
}
public class MyAttribute : System.Attribute
{
public MyAttribute(string name1) { }
}
");
comp.VerifyDiagnostics(
// (8,24): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// [My(typeof(parameter))] // 1
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(8, 24),
// (12,16): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// [My(typeof(parameter))] // 2
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(12, 16)
);
VerifyParameter(comp, 0);
VerifyParameter(comp, 1);
}
[Fact]
public void ParameterScope_NotInMethodAttribute()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ =
[My(parameter)] // 1
void (int parameter) => { };
}
[My(parameter)] // 2
void M2(int parameter) { }
}
public class MyAttribute : System.Attribute
{
public MyAttribute(object o) { }
}
");
comp.VerifyDiagnostics(
// (7,17): error CS0103: The name 'parameter' does not exist in the current context
// [My(parameter)] // 1
Diagnostic(ErrorCode.ERR_NameNotInContext, "parameter").WithArguments("parameter").WithLocation(7, 17),
// (11,9): error CS0103: The name 'parameter' does not exist in the current context
// [My(parameter)] // 2
Diagnostic(ErrorCode.ERR_NameNotInContext, "parameter").WithArguments("parameter").WithLocation(11, 9)
);
VerifyParameter(comp, 0);
VerifyParameter(comp, 1);
}
[Fact]
public void ParameterScope_NotInMethodAttributeTypeArgument()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ =
[My<parameter>] // 1
void (int parameter) => { };
}
[My<parameter>] // 2
void M2(int parameter) { }
}
public class MyAttribute<T> : System.Attribute
{
}
");
comp.VerifyDiagnostics(
// (7,17): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// [My<parameter>] // 1
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(7, 17),
// (11,9): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// [My<parameter>] // 2
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(11, 9)
);
VerifyParameter(comp, 0);
VerifyParameter(comp, 1);
}
[Fact]
public void ParameterScope_NotAsMethodAttributeType()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ =
[parameter] // 1
void (System.Attribute parameter) => { };
}
[parameter] // 2
void M2(System.Attribute parameter) { }
}
");
comp.VerifyDiagnostics(
// (7,14): error CS0246: The type or namespace name 'parameterAttribute' could not be found (are you missing a using directive or an assembly reference?)
// [parameter] // 1
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameterAttribute").WithLocation(7, 14),
// (7,14): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// [parameter] // 1
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(7, 14),
// (11,6): error CS0246: The type or namespace name 'parameterAttribute' could not be found (are you missing a using directive or an assembly reference?)
// [parameter] // 2
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameterAttribute").WithLocation(11, 6),
// (11,6): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// [parameter] // 2
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(11, 6)
);
VerifyParameter(comp, 0);
VerifyParameter(comp, 1);
}
[Fact]
public void ParameterScope_NotInParameterAttribute()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ = void ([My(parameter)] int parameter) => throw null;
}
void M2([My(parameter)] int parameter) => throw null;
}
public class MyAttribute : System.Attribute
{
public MyAttribute(string name1) { }
}
");
comp.VerifyDiagnostics(
// (6,27): error CS0103: The name 'parameter' does not exist in the current context
// var _ = void ([My(parameter)] int parameter) => throw null;
Diagnostic(ErrorCode.ERR_NameNotInContext, "parameter").WithArguments("parameter").WithLocation(6, 27),
// (9,17): error CS0103: The name 'parameter' does not exist in the current context
// void M2([My(parameter)] int parameter) => throw null;
Diagnostic(ErrorCode.ERR_NameNotInContext, "parameter").WithArguments("parameter").WithLocation(9, 17)
);
VerifyParameter(comp, 0);
VerifyParameter(comp, 1);
}
[Fact]
public void ParameterScope_InParameterDefaultValueNameOf()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ = void (string parameter = nameof(parameter)) => throw null;
}
void M2(string parameter = nameof(parameter)) => throw null;
}
");
comp.VerifyDiagnostics(
// (6,49): error CS0103: The name 'parameter' does not exist in the current context
// var _ = void (string parameter = nameof(parameter)) => throw null;
Diagnostic(ErrorCode.ERR_NameNotInContext, "parameter").WithArguments("parameter").WithLocation(6, 49),
// (9,39): error CS0103: The name 'parameter' does not exist in the current context
// void M2(string parameter = nameof(parameter)) => throw null;
Diagnostic(ErrorCode.ERR_NameNotInContext, "parameter").WithArguments("parameter").WithLocation(9, 39));
}
[Fact]
public void ParameterScope_NotAsParameterAttributeType()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ = void ([parameter] System.Attribute parameter) => throw null;
}
void M2([parameter] System.Attribute parameter) => throw null;
}
");
comp.VerifyDiagnostics(
// (6,24): error CS0246: The type or namespace name 'parameterAttribute' could not be found (are you missing a using directive or an assembly reference?)
// var _ = void ([parameter] System.Attribute parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameterAttribute").WithLocation(6, 24),
// (6,24): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// var _ = void ([parameter] System.Attribute parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(6, 24),
// (9,14): error CS0246: The type or namespace name 'parameterAttribute' could not be found (are you missing a using directive or an assembly reference?)
// void M2([parameter] System.Attribute parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameterAttribute").WithLocation(9, 14),
// (9,14): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// void M2([parameter] System.Attribute parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(9, 14)
);
VerifyParameter(comp, 0);
VerifyParameter(comp, 1);
}
[Fact]
public void ParameterScope_NotInReturnType()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ = parameter (int parameter) => throw null;
}
parameter M2(int parameter) => throw null;
}
");
comp.VerifyDiagnostics(
// (6,17): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// var _ = parameter (int parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(6, 17),
// (9,5): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// parameter M2(int parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(9, 5)
);
}
[Fact]
public void ParameterScope_NotInParameterType()
{
var comp = CreateCompilation(@"
class C
{
void M()
{
var _ = void (parameter parameter) => throw null;
}
void M2(parameter parameter) => throw null;
}
");
comp.VerifyDiagnostics(
// (6,23): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// var _ = void (parameter parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(6, 23),
// (9,13): error CS0246: The type or namespace name 'parameter' could not be found (are you missing a using directive or an assembly reference?)
// void M2(parameter parameter) => throw null;
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "parameter").WithArguments("parameter").WithLocation(9, 13)
);
}
[Fact, WorkItem(61143, "https://github.com/dotnet/roslyn/issues/61143")]
public void ParameterScope_LambdaDiscardParameter()
{
var comp = CreateCompilation(@"
class AAttribute : System.Attribute
{
public AAttribute(string s) { }
}
class C
{
void M(int _)
{
System.Func<string, string, int> a = [A(nameof(_))] (_, _) => 0;
}
}
");
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var discard = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>()
.Where(i => i.Identifier.ValueText == "_")
.Where(i => i.Ancestors().Any(a => a.IsKind(SyntaxKind.InvocationExpression)))
.Single();
Assert.Equal("System.Int32 _", model.GetSymbolInfo(discard).Symbol.ToTestDisplayString());
}
[Fact, WorkItem(61143, "https://github.com/dotnet/roslyn/issues/61143")]
public void ParameterScope_LambdaUnderscoreParameter()
{
var comp = CreateCompilation(@"
class AAttribute : System.Attribute
{
public AAttribute(string s) { }
}
class C
{
void M(int _)
{
System.Func<string, string, int> a = [A(nameof(_))] (_, x) => 0;
}
}
");
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var underscore = tree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>()
.Where(i => i.Identifier.ValueText == "_")
.Where(i => i.Ancestors().Any(a => a.IsKind(SyntaxKind.InvocationExpression)))
.Single();
Assert.Equal("System.String _", model.GetSymbolInfo(underscore).Symbol.ToTestDisplayString());
}
[WorkItem(62085, "https://github.com/dotnet/roslyn/issues/62085")]
[Fact]
public void DuplicateRef()
{
var source =
@"delegate void D(ref int i);
class Program
{
static void Main()
{
D d1 = (ref ref int i) => { };
D d2 = (in ref int i) => { };
D d3 = (out ref int i) => { };
}
}";
var comp = CreateCompilation(source);
comp.VerifyEmitDiagnostics(
// (6,21): error CS1107: A parameter can only have one 'ref' modifier
// D d1 = (ref ref int i) => { };
Diagnostic(ErrorCode.ERR_DupParamMod, "ref").WithArguments("ref").WithLocation(6, 21),
// (7,16): warning CS9198: Reference kind modifier of parameter 'in int i' doesn't match the corresponding parameter 'ref int i' in target.
// D d2 = (in ref int i) => { };
Diagnostic(ErrorCode.WRN_TargetDifferentRefness, "(in ref int i) => { }").WithArguments("in int i", "ref int i").WithLocation(7, 16),
// (7,20): error CS8328: The parameter modifier 'ref' cannot be used with 'in'
// D d2 = (in ref int i) => { };
Diagnostic(ErrorCode.ERR_BadParameterModifiers, "ref").WithArguments("ref", "in").WithLocation(7, 20),
// (8,16): error CS0177: The out parameter 'i' must be assigned to before control leaves the current method
// D d3 = (out ref int i) => { };
Diagnostic(ErrorCode.ERR_ParamUnassigned, "(out ref int i) => { }").WithArguments("i").WithLocation(8, 16),
// (8,21): error CS8328: The parameter modifier 'ref' cannot be used with 'out'
// D d3 = (out ref int i) => { };
Diagnostic(ErrorCode.ERR_BadParameterModifiers, "ref").WithArguments("ref", "out").WithLocation(8, 21),
// (8,29): error CS1676: Parameter 1 must be declared with the 'ref' keyword
// D d3 = (out ref int i) => { };
Diagnostic(ErrorCode.ERR_BadParamRef, "i").WithArguments("1", "ref").WithLocation(8, 29),
// (8,32): error CS1661: Cannot convert lambda expression to type 'D' because the parameter types do not match the delegate parameter types
// D d3 = (out ref int i) => { };
Diagnostic(ErrorCode.ERR_CantConvAnonMethParams, "=>").WithArguments("lambda expression", "D").WithLocation(8, 32));
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var lambdas = tree.GetRoot().DescendantNodes().OfType<ParenthesizedLambdaExpressionSyntax>().Select(e => model.GetSymbolInfo(e).Symbol.GetSymbol<LambdaSymbol>()).ToArray();
Assert.Equal(RefKind.Ref, lambdas[0].Parameters[0].RefKind);
Assert.Equal(RefKind.In, lambdas[1].Parameters[0].RefKind);
Assert.Equal(RefKind.Out, lambdas[2].Parameters[0].RefKind);
}
[Fact]
public void StaticPartialLambda()
{
CreateCompilation("""
class C
{
void M()
{
System.Action x = static partial () => { };
}
}
""").VerifyDiagnostics(
// (5,34): error CS0246: The type or namespace name 'partial' could not be found (are you missing a using directive or an assembly reference?)
// System.Action x = static partial () => { };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "partial").WithArguments("partial").WithLocation(5, 34),
// (5,45): error CS8934: Cannot convert lambda expression to type 'Action' because the return type does not match the delegate return type
// System.Action x = static partial () => { };
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Action").WithLocation(5, 45));
}
[Fact]
public void PartialStaticLambda()
{
CreateCompilation("""
class C
{
void M()
{
System.Action x = partial static () => { };
}
}
""").VerifyDiagnostics(
// (5,27): error CS0103: The name 'partial' does not exist in the current context
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_NameNotInContext, "partial").WithArguments("partial").WithLocation(5, 27),
// (5,35): error CS1002: ; expected
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_SemicolonExpected, "static").WithLocation(5, 35),
// (5,35): error CS0106: The modifier 'static' is not valid for this item
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_BadMemberFlag, "static").WithArguments("static").WithLocation(5, 35),
// (5,43): error CS8124: Tuple must contain at least two elements.
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_TupleTooFewElements, ")").WithLocation(5, 43),
// (5,45): error CS1001: Identifier expected
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_IdentifierExpected, "=>").WithLocation(5, 45),
// (5,45): error CS1003: Syntax error, ',' expected
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_SyntaxError, "=>").WithArguments(",").WithLocation(5, 45),
// (5,48): error CS1002: ; expected
// System.Action x = partial static () => { };
Diagnostic(ErrorCode.ERR_SemicolonExpected, "{").WithLocation(5, 48));
}
[Fact]
public void PartialLambda()
{
CreateCompilation("""
class C
{
void M()
{
System.Action x = partial () => { };
}
}
""").VerifyDiagnostics(
// (5,27): error CS0246: The type or namespace name 'partial' could not be found (are you missing a using directive or an assembly reference?)
// System.Action x = partial () => { };
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "partial").WithArguments("partial").WithLocation(5, 27),
// (5,38): error CS8934: Cannot convert lambda expression to type 'Action' because the return type does not match the delegate return type
// System.Action x = partial () => { };
Diagnostic(ErrorCode.ERR_CantConvAnonMethReturnType, "=>").WithArguments("lambda expression", "System.Action").WithLocation(5, 38));
}
[WorkItem(61013, "https://github.com/dotnet/roslyn/issues/61013")]
[Fact]
public void InvalidCast()
{
var source = """
using System;
#nullable enable
internal class Program
{
void Main(string[] args)
{
Choice(args.Length > 0
? (Action)(() => DS1()
: () => DS2(args[0]));
}
void DS1()
{ }
void DS2(string a)
{ }
void Choice(Action a)
{
a();
}
}
""";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular8);
var syntaxTree = comp.SyntaxTrees[0];
var action = syntaxTree.GetRoot().DescendantNodes().OfType<IdentifierNameSyntax>().First(id => id.Identifier.ValueText == "Action");
var model = comp.GetSemanticModel(syntaxTree);
AssertEx.Equal("System.Action", model.GetTypeInfo(action).Type.ToTestDisplayString());
}
[Fact]
[WorkItem(64392, "https://github.com/dotnet/roslyn/issues/64392")]
public void ReferToFieldWithinLambdaInTypeAttribute_01()
{
var source = @"
[Display(x => $""{Name}"")]
public class Test
{
[Display(Name = ""Name"")]
public string Name { get; }
}
public class DisplayAttribute : System.Attribute
{
public DisplayAttribute() { }
}
";
var comp = CreateCompilation(source);
comp.VerifyEmitDiagnostics(
// (2,2): error CS1729: 'DisplayAttribute' does not contain a constructor that takes 1 arguments
// [Display(x => $"{Name}")]
Diagnostic(ErrorCode.ERR_BadCtorArgCount, @"Display(x => $""{Name}"")").WithArguments("DisplayAttribute", "1").WithLocation(2, 2),
// (5,14): error CS0246: The type or namespace name 'Name' could not be found (are you missing a using directive or an assembly reference?)
// [Display(Name = "Name")]
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Name").WithArguments("Name").WithLocation(5, 14)
);
}
[Fact]
[WorkItem(64392, "https://github.com/dotnet/roslyn/issues/64392")]
public void ReferToFieldWithinLambdaInTypeAttribute_02()
{
var source = @"
[Display(x => Name)]
public class Test
{
[Display(Name = ""Name"")]
public string Name { get; }
}
public class DisplayAttribute : System.Attribute
{
public DisplayAttribute() { }
}
";
var comp = CreateCompilation(source);
comp.VerifyEmitDiagnostics(
// (2,2): error CS1729: 'DisplayAttribute' does not contain a constructor that takes 1 arguments
// [Display(x => Name)]
Diagnostic(ErrorCode.ERR_BadCtorArgCount, "Display(x => Name)").WithArguments("DisplayAttribute", "1").WithLocation(2, 2),
// (5,14): error CS0246: The type or namespace name 'Name' could not be found (are you missing a using directive or an assembly reference?)
// [Display(Name = "Name")]
Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Name").WithArguments("Name").WithLocation(5, 14)
);
}
[Fact, WorkItem(64985, "https://github.com/dotnet/roslyn/issues/64985")]
public void DelegateConversions_ImplicitlyTypedParameter_RefParameter()
{
var source = """
struct R { }
delegate R D1(ref R r);
class Program
{
static void Main()
{
D1 d1 = r1 => r1; // 1
M(r2 => r2); // 2
}
static void M(D1 d1) { }
}
""";
var comp = CreateCompilation(source, targetFramework: TargetFramework.Net70);
comp.VerifyDiagnostics(
// (9,17): error CS1676: Parameter 1 must be declared with the 'ref' keyword
// D1 d1 = r1 => r1; // 1
Diagnostic(ErrorCode.ERR_BadParamRef, "r1").WithArguments("1", "ref").WithLocation(9, 17),
// (10,11): error CS1676: Parameter 1 must be declared with the 'ref' keyword
// M(r2 => r2); // 2
Diagnostic(ErrorCode.ERR_BadParamRef, "r2").WithArguments("1", "ref").WithLocation(10, 11)
);
var syntaxTree = comp.SyntaxTrees[0];
var root = syntaxTree.GetRoot();
var model = comp.GetSemanticModel(syntaxTree);
var lambdas = root.DescendantNodes().OfType<LambdaExpressionSyntax>().ToArray();
Assert.Equal("r1 => r1", lambdas[0].ToString());
var lambdaParameter1 = model.GetSymbolInfo(lambdas[0]).Symbol.GetParameters()[0];
Assert.Equal("? r1", lambdaParameter1.ToTestDisplayString());
Assert.Equal(RefKind.None, lambdaParameter1.RefKind);
Assert.Equal("r2 => r2", lambdas[1].ToString());
var lambdaParameter2 = model.GetSymbolInfo(lambdas[1]).Symbol.GetParameters()[0];
Assert.Equal("R r2", lambdaParameter2.ToTestDisplayString());
Assert.Equal(RefKind.None, lambdaParameter2.RefKind);
}
[Fact]
public void LambdaWithExplicitDefaultParam()
{
var source =
@"class Program
{
public static void Main(string[] args)
{
var lam1 = (int x = 7) => x;
lam1();
}
}
";
CreateCompilation(source, parseOptions: TestOptions.Regular11).VerifyDiagnostics(
// (5,27): error CS9058: Feature 'lambda optional parameters' is not available in C# 11.0. Please use language version 12.0 or greater.
// var lam1 = (int x = 7) => x;
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "=").WithArguments("lambda optional parameters", "12.0").WithLocation(5, 27));
CreateCompilation(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics();
}
[Theory]
[InlineData(LanguageVersion.CSharp11)]
[InlineData(LanguageVersion.CSharp12)]
public void AnonymousMethodWithExplicitDefaultParam(LanguageVersion languageVersion)
{
var source = """
class Program
{
public void M()
{
var lam = delegate(int x = 7) { return x; };
lam();
}
}
""";
var comp = CreateCompilation(source, parseOptions: TestOptions.Regular.WithLanguageVersion(languageVersion));
comp.VerifyDiagnostics(
// (5,34): error CS1065: Default values are not valid in this context.
// var lam = delegate(int x = 7) { return x; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(5, 34));
}
[Fact]
public void LambdaWithImplicitDefaultParam1()
{
var source =
@"class Program
{
public static void Main(string[] args)
{
var lam1 = (x = 7) => x;
lam1();
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,20): error CS8917: The delegate type could not be inferred.
// var lam1 = (x = 7) => x;
Diagnostic(ErrorCode.ERR_CannotInferDelegateType, "(x = 7) => x").WithLocation(5, 20),
// (5,21): error CS9098: Default not allowed for implicitly typed lambda parameter 'x'
// var lam1 = (x = 7) => x;
Diagnostic(ErrorCode.ERR_ImplicitlyTypedDefaultParameter, "x").WithArguments("x").WithLocation(5, 21));
}
[Fact]
public void LambdaWithImplicitDefaultParam2()
{
var source =
@"class Program
{
public static void Main(string[] args)
{
var lam = (string s = null, x = 7, double d = 3.14) => { };
lam();
}
}";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,19): error CS8917: The delegate type could not be inferred.
// var lam = (string s = null, x = 7, double d = 3.14) => { };
Diagnostic(ErrorCode.ERR_CannotInferDelegateType, "(string s = null, x = 7, double d = 3.14) => { }").WithLocation(5, 19),
// (5,37): error CS0748: Inconsistent lambda parameter usage; parameter types must be all explicit or all implicit
// var lam = (string s = null, x = 7, double d = 3.14) => { };
Diagnostic(ErrorCode.ERR_InconsistentLambdaParameterUsage, "x").WithLocation(5, 37),
// (5,37): error CS9098: Implicitly typed lambda parameter 'x' cannot have a default value.
// var lam = (string s = null, x = 7, double d = 3.14) => { };
Diagnostic(ErrorCode.ERR_ImplicitlyTypedDefaultParameter, "x").WithArguments("x").WithLocation(5, 37));
}
[Fact]
public void LambdaWithDefaultBeforeRequired1()
{
var source =
@"class Program
{
public static void Main()
{
var lam = (int a = 3, int b) => { return a + b; };
}
}
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,36): error CS1737: Optional parameters must appear after all required parameters
// var lam = (int a = 3, int b) => { return a + b; };
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(5, 36));
}
[Fact]
public void AnonymousMethodDefaultBeforeRequired1()
{
var source =
@"class Program
{
public static void Main()
{
var lam = delegate(int a = 3, int b) { return a + b; };
}
}
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,34): error CS1065: Default values are not valid in this context.
// var lam = delegate(int a = 3, int b) { return a + b; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(5, 34),
// (5,44): error CS1737: Optional parameters must appear after all required parameters
// var lam = delegate(int a = 3, int b) { return a + b; };
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(5, 44));
}
[Fact]
public void LambdaWithDefaultBeforeRequired2()
{
var source =
@"class Program
{
public static void Main()
{
var lam = (int x, int y = 3, int z) => x + y + z;
}
}
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,43): error CS1737: Optional parameters must appear after all required parameters
// var lam = (int x, int y = 3, int z) => x + y + z;
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(5, 43));
}
[Fact]
public void AnonymousMethodDefaultBeforeRequired2()
{
var source =
@"class Program
{
public static void Main()
{
var lam = delegate(int x, int y = 3, int z) { return x + y + z; };
}
}
";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,41): error CS1065: Default values are not valid in this context.
// var lam = delegate(int x, int y = 3, int z) { return x + y + z; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(5, 41),
// (5,51): error CS1737: Optional parameters must appear after all required parameters
// var lam = delegate(int x, int y = 3, int z) { return x + y + z; };
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(5, 51));
}
[Fact]
public void LambdaWithDefaultTypeMismatchLiteral()
{
var source = """
class Program
{
public static void Main()
{
var lam = (int x = "abcdef") => x;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,24): error CS1750: A value of type 'string' cannot be used as a default parameter because there are no standard conversions to type 'int'
// var lam = (int x = "abcdef") => x;
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "x").WithArguments("string", "int").WithLocation(5, 24));
}
[Fact]
public void AnonymousMethodWithDefaultTypeMismatchLiteral()
{
var source = """
class Program
{
public static void Main()
{
var lam = delegate(int x = "abcdef") { return x; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,32): error CS1750: A value of type 'string' cannot be used as a default parameter because there are no standard conversions to type 'int'
// var lam = delegate(int x = "abcdef") { return x; };
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "x").WithArguments("string", "int").WithLocation(5, 32),
// (5,34): error CS1065: Default values are not valid in this context.
// var lam = delegate(int x = "abcdef") { return x; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(5, 34));
}
[Fact]
public void LambdaWithNonConstantDefault()
{
var source = """
class C
{
object field;
public object Field => @field;
public C(object f) { field = f; }
}
class Program
{
public static void Main()
{
var lam = (C c = new C(null)) => c.Field;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (14,26): error CS1736: Default parameter value for 'c' must be a compile-time constant
// var lam = (C c = new C(null)) => c.Field;
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "new C(null)").WithArguments("c").WithLocation(14, 26));
}
[Fact]
public void AnonymousMethodWithNonConstantDefault()
{
var source = """
class C
{
object field;
public object Field => @field;
public C(object f) { field = f; }
}
class Program
{
public static void Main()
{
var lam = delegate(C c = new C(null)) { return c.Field; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (14,32): error CS1065: Default values are not valid in this context.
// var lam = delegate(C c = new C(null)) { return c.Field; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(14, 32),
// (14,34): error CS1736: Default parameter value for 'c' must be a compile-time constant
// var lam = delegate(C c = new C(null)) { return c.Field; };
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "new C(null)").WithArguments("c").WithLocation(14, 34));
}
[Fact]
public void LambdaWithNonConstantDefaultTypeMismatch()
{
var source = """
class Program
{
static int add(int x, int y) => x + y;
public static void Main(string[] args)
{
var lam = (string s = add(1, 2)) => s;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(// (7,31): error CS1736: Default parameter value for 's' must be a compile-time constant
// var lam = (string s = add(1, 2)) => s;
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "add(1, 2)").WithArguments("s").WithLocation(7, 31));
}
[Fact]
public void AnonymousMethodWithNonConstantDefaultTypeMismatch()
{
var source = """
class Program
{
static int add(int x, int y) => x + y;
public static void Main(string[] args)
{
var lam = delegate(string s = add(1, 2)) { return s; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,37): error CS1065: Default values are not valid in this context.
// var lam = delegate(string s = add(1, 2)) { return s; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(7, 37),
// (7,39): error CS1736: Default parameter value for 's' must be a compile-time constant
// var lam = delegate(string s = add(1, 2)) { return s; };
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "add(1, 2)").WithArguments("s").WithLocation(7, 39));
}
[Fact]
public void LambdaWithComplexConstantExpression()
{
var source = """
class Program
{
const bool b1 = false;
const bool b2 = true;
const int num1 = 1;
const int num2 = 2;
const int num3 = 3;
public static void Main(string[] args)
{
var fn = (int arg = b1 ? num1 : b2 ? num2 : num3) => arg;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void AnonymousMethodWithComplexConstantExpression()
{
var source = """
class Program
{
const bool b1 = false;
const bool b2 = true;
const int num1 = 1;
const int num2 = 2;
const int num3 = 3;
public static void Main(string[] args)
{
var fn = delegate(int arg = b1 ? num1 : b2 ? num2 : num3) { return arg; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (12,35): error CS1065: Default values are not valid in this context.
// var fn = delegate(int arg = b1 ? num1 : b2 ? num2 : num3) { return arg; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(12, 35));
}
[Fact]
public void LambdaDefaultLocalConstantExpression()
{
var source = """
class Program
{
public static void Main(string[] args)
{
const int i1 = 1;
const int i2 = 2;
var func = (int arg = i1 + i2) => arg + 1;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void AnonymousMethodDefaultLocalConstantExpression()
{
var source = """
class Program
{
public static void Main(string[] args)
{
const int i1 = 1;
const int i2 = 2;
var func = delegate(int arg = i1 + i2) { return arg + 1; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,37): error CS1065: Default values are not valid in this context.
// var func = delegate(int arg = i1 + i2) { return arg + 1; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(7, 37));
}
[Fact]
public void AsyncLambdaWithDefaultParameters()
{
var source = """
using System.Threading.Tasks;
class Program
{
public static void Main(string[] args)
{
var lam = async (int delay = 10) => await Task.Delay(delay);
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void StaticLambdaWithDefaultParameters()
{
var source = """
class Program
{
public static void Main()
{
var lam = static (string s = "str") => s;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaWithDefaultParametersAndRefOutModifiers()
{
var source = """
class Program
{
public static void Main()
{
var lam = (ref int x, out object y, double c = 4.59) => { y = c + (double) x; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void AnonymousMethodWithDefaultParametersAndRefOutModifiers()
{
var source = """
class Program
{
public static void Main()
{
var lam = delegate(ref int x, out object y, double c = 4.59) { y = c + (double) x; };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,62): error CS1065: Default values are not valid in this context.
// var lam = delegate(ref int x, out object y, double c = 4.59) { y = c + (double) x; };
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(5, 62));
}
[Fact]
public void LambdaWithMultipleDefaultParameters()
{
var source = """
class Program
{
public static void Main()
{
var lam = (int u, string v, object w, int x = 10, int y = 3, int z = 4) => x + y + z;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaDefaultParamUsageAnalysis()
{
var source = """
class Program
{
void M(int a, int b)
{
var _ = (int i = M2(a)) => { }; // parameter 'a' should be considered read/used
}
static int M2(int j) => j;
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,26): error CS1736: Default parameter value for 'i' must be a compile-time constant
// var _ = (int i = M2(a)) => { }; // parameter 'a' should be considered read/used
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "M2(a)").WithArguments("i").WithLocation(5, 26));
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
// Find method parameters.
var method = comp.GetMember<MethodSymbol>("Program.M").GetPublicSymbol();
Assert.Equal(2, method.Parameters.Length);
var a = method.Parameters[0];
Assert.Equal("a", a.Name);
var b = method.Parameters[1];
Assert.Equal("b", b.Name);
// Analyze flow inside method's body.
var methodSyntax = (MethodDeclarationSyntax)method.DeclaringSyntaxReferences.Single().GetSyntax();
var dataFlow = model.AnalyzeDataFlow(methodSyntax.Body);
Assert.Contains(a, dataFlow.ReadInside);
Assert.DoesNotContain(b, dataFlow.ReadInside);
}
[Fact]
public void AnonymousMethodDefaultParameterUsageAnalysis()
{
var source = """
class Program
{
void M(int a)
{
var _ = delegate(int i = M2(a)) { }; // parameter 'a' should be considered read/used
}
static int M2(int j) => j;
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,31): error CS1065: Default values are not valid in this context.
// var _ = delegate(int i = M2(a)) { }; // parameter 'a' should be considered read/used
Diagnostic(ErrorCode.ERR_DefaultValueNotAllowed, "=").WithLocation(5, 31),
// (5,33): error CS1736: Default parameter value for 'i' must be a compile-time constant
// var _ = delegate(int i = M2(a)) { }; // parameter 'a' should be considered read/used
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "M2(a)").WithArguments("i").WithLocation(5, 33));
}
[Fact]
public void LambdaDefaultWithinCheckedContext()
{
var source = """
class Program
{
void M()
{
var _ = (int i = int.MaxValue + 1) => i;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,26): error CS0220: The operation overflows at compile time in checked mode
// var _ = (int i = int.MaxValue + 1) => i;
Diagnostic(ErrorCode.ERR_CheckedOverflow, "int.MaxValue + 1").WithLocation(5, 26));
}
[Fact]
public void LambdaDefaultWithinUncheckedContext()
{
var source = """
class Program
{
void M()
{
unchecked
{
var _ = (int i = int.MaxValue + 1) => i;
}
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaDefaultWithinNestedScope()
{
var source = """
class Program
{
void M()
{
{
const string s = "abcdef";
var _ = (string str = s) => s;
}
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaDefaultInDifferentNestedScope()
{
var source = """
class Program
{
void M()
{
{
const string s = "abcdef";
}
var _ = (string str = s) => str;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (6,26): warning CS0219: The variable 's' is assigned but its value is never used
// const string s = "abcdef";
Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "s").WithArguments("s").WithLocation(6, 26),
// (8,31): error CS0103: The name 's' does not exist in the current context
// var _ = (string str = s) => s;
Diagnostic(ErrorCode.ERR_NameNotInContext, "s").WithArguments("s").WithLocation(8, 31));
}
[Fact]
public void LambdaDefaultLocalConstantSameScope_PreDefinition()
{
var source = """
class Program
{
void M()
{
const string s = "abcdef";
var _ = (string str = s) => s;
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics();
}
[Fact]
public void LambdaDefaultLocalConstantSameScope_PostDefinition()
{
var source = """
class Program
{
void M()
{
var lam = (string str = s) => { };
const string s = "abcdef";
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (5,27): error CS1750: A value of type 'var' cannot be used as a default parameter because there are no standard conversions to type 'string'
// var lam = (string str = s) => { };
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "str").WithArguments("var", "string").WithLocation(5, 27),
// (5,33): error CS0841: Cannot use local variable 's' before it is declared
// var lam = (string str = s) => { };
Diagnostic(ErrorCode.ERR_VariableUsedBeforeDeclaration, "s").WithArguments("s").WithLocation(5, 33));
}
[Fact]
public void LambdaDefaultSelfReference()
{
var source = """
using System;
class Program
{
public static void Main(string[] args)
{
var lam = (Delegate d = lam) => { };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,29): error CS1750: A value of type 'var' cannot be used as a default parameter because there are no standard conversions to type 'Delegate'
// var lam = (Delegate d = lam) => { };
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "d").WithArguments("var", "System.Delegate").WithLocation(7, 29),
// (7,33): error CS0841: Cannot use local variable 'lam' before it is declared
// var lam = (Delegate d = lam) => { };
Diagnostic(ErrorCode.ERR_VariableUsedBeforeDeclaration, "lam").WithArguments("lam").WithLocation(7, 33));
}
[Fact]
public void LambdaDefaultSelfReference_ParameterBefore()
{
var source = """
using System;
class Program
{
public static void Main(string[] args)
{
var lam = (int x, Delegate d = lam) => { };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,36): error CS1750: A value of type 'var' cannot be used as a default parameter because there are no standard conversions to type 'Delegate'
// var lam = (int x, Delegate d = lam) => { };
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "d").WithArguments("var", "System.Delegate").WithLocation(7, 36),
// (7,40): error CS0841: Cannot use local variable 'lam' before it is declared
// var lam = (int x, Delegate d = lam) => { };
Diagnostic(ErrorCode.ERR_VariableUsedBeforeDeclaration, "lam").WithArguments("lam").WithLocation(7, 40));
}
[Fact]
public void LambdaDefaultSelfReference_ParameterAfter()
{
var source = """
using System;
class Program
{
public static void Main(string[] args)
{
var lam = (Delegate d = lam, int x) => { };
}
}
""";
var comp = CreateCompilation(source);
comp.VerifyDiagnostics(
// (7,29): error CS1750: A value of type 'var' cannot be used as a default parameter because there are no standard conversions to type 'Delegate'
// var lam = (Delegate d = lam, int x) => { };
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "d").WithArguments("var", "System.Delegate").WithLocation(7, 29),
// (7,33): error CS0841: Cannot use local variable 'lam' before it is declared
// var lam = (Delegate d = lam, int x) => { };
Diagnostic(ErrorCode.ERR_VariableUsedBeforeDeclaration, "lam").WithArguments("lam").WithLocation(7, 33),
// (7,43): error CS1737: Optional parameters must appear after all required parameters
// var lam = (Delegate d = lam, int x) => { };
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(7, 43));
}
[Fact]
public void Lambda_BadDefault_ExplicitReturnType()
{
var source = """
class Program
{
static int f(int x) => 2 * x;
public static void Main(string[] args)
{
var lam = int (int p = f(3)) => p;
}
}
""";
CreateCompilation(source).VerifyDiagnostics(
// (6,32): error CS1736: Default parameter value for 'p' must be a compile-time constant
// var lam = int (int p = f(3)) => p;
Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "f(3)").WithArguments("p").WithLocation(6, 32));
}
[Fact]
public void LambdaDefault_LongString()
{
var longString = "";
for (int i = 0; i < 100; i++)
{
longString += i.ToString();
}
var source = $@"
class Program
{{
delegate void Del(string s = ""abc"");
public static void Main(string[] args)
{{
Del del = (string s = ""{longString}"") => {{ }};
}}
}}
";
CreateCompilation(source).VerifyDiagnostics(
// (7,27): warning CS9099: Parameter 1 has default value '"0123456..."' in lambda but '"abc"' in the target delegate type.
// Del del = (string s = "0123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899") => { };
Diagnostic(ErrorCode.WRN_OptionalParamValueMismatch, "s").WithArguments("1", @"""0123456...""", @"""abc""").WithLocation(7, 27));
}
[Fact]
public void LambdaDefault_InvalidConstantConversion()
{
var source = @"
class Program
{
public static void Main()
{
var lam = (string s = 1) => s;
}
}
";
CreateCompilation(source).VerifyDiagnostics(
// (6,27): error CS1750: A value of type 'int' cannot be used as a default parameter because there are no standard conversions to type 'string'
// var lam = (string s = 1) => s;
Diagnostic(ErrorCode.ERR_NoConversionForDefaultParam, "s").WithArguments("int", "string").WithLocation(6, 27));
}
[Theory]
[InlineData("ref")]
[InlineData("out")]
public void LambdaDefault_RefOut(string modifier)
{
var source = $$"""
var lam = void ({{modifier}} int x = 1) => throw null;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,17): error CS1741: A ref or out parameter cannot have a default value
// var lam = void (ref int x = 1) => throw null;
Diagnostic(ErrorCode.ERR_RefOutDefaultValue, modifier).WithLocation(1, 17));
}
[Fact]
public void LambdaDefault_ThisModifier()
{
var source = """
var lam = void (this int x = 1) => throw null;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,17): error CS1041: Identifier expected; 'this' is a keyword
// var lam = void (this int x = 1) => throw null;
Diagnostic(ErrorCode.ERR_IdentifierExpectedKW, "this").WithArguments("", "this").WithLocation(1, 17));
}
[Fact]
public void LambdaWithDefaultParameterAndParams()
{
var source = """
class Program
{
public static void Main()
{
var lam = (int i = 3, params int[] args) => i;
}
}
""";
CreateCompilation(source).VerifyDiagnostics();
}
[Fact]
public void LambdaWithDefaultParameter_RequiredMissing()
{
var source = """
class Program
{
public static void Main()
{
var lam = (int a, int b, int c = 3) => a + b * c;
lam(5);
}
}
""";
CreateCompilation(source).VerifyDiagnostics(
// (6,9): error CS7036: There is no argument given that corresponds to the required parameter 'arg2' of '<anonymous delegate>'
// lam(5);
Diagnostic(ErrorCode.ERR_NoCorrespondingArgument, "lam").WithArguments("arg2", "<anonymous delegate>").WithLocation(6, 9));
}
[Fact]
public void LambdaWithDefaultParameter_SymbolInfo()
{
var source = """
using System.Runtime.InteropServices;
var lam1 = (int a, int b = 1) => a + b;
var lam2 = ([Optional] int x) => x;
var lam3 = ([DefaultParameterValue(2)] int x) => x;
var lam4 = ([Optional, DefaultParameterValue(3)] int x) => x;
""";
var comp = CreateCompilation(source).VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var lambdas = tree.GetRoot().DescendantNodes()
.Where(n => n.IsKind(SyntaxKind.ParenthesizedLambdaExpression))
.Select(n => (Node: n, Symbol: (IMethodSymbol)model.GetSymbolInfo(n).Symbol))
.ToImmutableArray();
Assert.Equal(4, lambdas.Length);
// lam1
Assert.Equal("(int a, int b = 1) => a + b", lambdas[0].Node.ToString());
Assert.Equal(2, lambdas[0].Symbol.Parameters.Length);
Assert.False(lambdas[0].Symbol.Parameters[0].IsOptional);
Assert.False(lambdas[0].Symbol.Parameters[0].HasExplicitDefaultValue);
Assert.Throws<InvalidOperationException>(() => lambdas[0].Symbol.Parameters[0].ExplicitDefaultValue);
Assert.True(lambdas[0].Symbol.Parameters[1].IsOptional);
Assert.True(lambdas[0].Symbol.Parameters[1].HasExplicitDefaultValue);
Assert.Equal(1, lambdas[0].Symbol.Parameters[1].ExplicitDefaultValue);
// lam2
Assert.Equal("([Optional] int x) => x", lambdas[1].Node.ToString());
Assert.Equal(1, lambdas[1].Symbol.Parameters.Length);
Assert.True(lambdas[1].Symbol.Parameters[0].IsOptional);
Assert.False(lambdas[2].Symbol.Parameters[0].HasExplicitDefaultValue);
Assert.Throws<InvalidOperationException>(() => lambdas[1].Symbol.Parameters[0].ExplicitDefaultValue);
// lam3
Assert.Equal("([DefaultParameterValue(2)] int x) => x", lambdas[2].Node.ToString());
Assert.Equal(1, lambdas[2].Symbol.Parameters.Length);
Assert.False(lambdas[2].Symbol.Parameters[0].IsOptional);
Assert.False(lambdas[2].Symbol.Parameters[0].HasExplicitDefaultValue);
Assert.Throws<InvalidOperationException>(() => lambdas[2].Symbol.Parameters[0].ExplicitDefaultValue);
// lam4
Assert.Equal("([Optional, DefaultParameterValue(3)] int x) => x", lambdas[3].Node.ToString());
Assert.Equal(1, lambdas[3].Symbol.Parameters.Length);
Assert.True(lambdas[3].Symbol.Parameters[0].IsOptional);
Assert.True(lambdas[3].Symbol.Parameters[0].HasExplicitDefaultValue);
Assert.Equal(3, lambdas[3].Symbol.Parameters[0].ExplicitDefaultValue);
}
[Fact]
public void LambdaWithDefaultParameter_EqualsValueClauseSyntax()
{
var source = """
var lam = (int a, int b = 1) => a + b;
""";
var comp = CreateCompilation(source).VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var lambda = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var equalsValue = lambda.DescendantNodes().OfType<EqualsValueClauseSyntax>().Single();
Assert.Equal("= 1", equalsValue.ToString());
var constantValue = model.GetConstantValue(equalsValue.Value);
Assert.True(constantValue.HasValue);
Assert.Equal(1, constantValue.Value);
}
[Fact]
public void LambdaWithDefaultParameter_SpeculativeSemanticModel()
{
var source = """
class C
{
public static int M1(int x) => x * 2;
public static void M2()
{
var lam = (int b) => b;
}
}
""";
var comp = CreateCompilation(source).VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var m2 = comp.GetMember<MethodSymbol>("C.M2").GetPublicSymbol();
var m2Syntax = (MethodDeclarationSyntax)m2.DeclaringSyntaxReferences.Single().GetSyntax();
var newStmt = SyntaxFactory.ParseStatement("var lam = (int b = M1(4)) => b;");
var newMethod = m2Syntax.WithBody(SyntaxFactory.Block(newStmt));
Assert.True(model.TryGetSpeculativeSemanticModelForMethodBody(m2Syntax.Body.SpanStart, newMethod, out var speculativeModel));
var newLambda = newMethod.DescendantNodes().OfType<LambdaExpressionSyntax>().Single();
var newLambdaSymbol = (IMethodSymbol)speculativeModel.GetSymbolInfo(newLambda).Symbol;
var newParam = newLambdaSymbol.Parameters.Single();
Assert.True(newParam.HasExplicitDefaultValue);
Assert.Null(newParam.ExplicitDefaultValue);
// Ensure errors from default parameter values are not added to declaration table.
model.GetDiagnostics().Verify();
}
[Fact]
public void LambdaWithDefaultParameter_SameSymbols()
{
var source = """
class C
{
public static void M()
{
const int N = 10;
var lam = (int a = N) => a;
var x = N;
}
}
""";
var comp = CreateCompilation(source).VerifyDiagnostics(
// (7,13): warning CS0219: The variable 'x' is assigned but its value is never used
// var x = N;
Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "x").WithArguments("x").WithLocation(7, 13));
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var decls = tree.GetRoot().DescendantNodes().OfType<LocalDeclarationStatementSyntax>().ToImmutableArray();
Assert.Equal(3, decls.Length);
Assert.Equal("const int N = 10;", decls[0].ToString());
var constSymbol = model.GetDeclaredSymbol(decls[0].Declaration.Variables.Single());
Assert.NotNull(constSymbol);
Assert.Equal("var lam = (int a = N) => a;", decls[1].ToString());
var defaultValue = decls[1].DescendantNodes().OfType<LambdaExpressionSyntax>().Single()
.DescendantNodes().OfType<EqualsValueClauseSyntax>().Single().Value;
var defaultValueSymbol = model.GetSymbolInfo(defaultValue).Symbol;
Assert.Same(constSymbol, defaultValueSymbol);
Assert.Equal("var x = N;", decls[2].ToString());
var lhs = decls[2].DescendantNodes().OfType<EqualsValueClauseSyntax>().Single().Value;
var lhsSymbol = model.GetSymbolInfo(lhs).Symbol;
Assert.Same(constSymbol, lhsSymbol);
}
[Fact]
public void LambdaWithDefaultParameter_MemberSemanticModel()
{
var source = """
class C
{
public static void M()
{
const int N = 10;
var lam = (int a = N) => a;
lam();
}
}
""";
var comp = CreateCompilation(source).VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
// Ensure MemberSemanticModel is parented to the correct outer SemanticModel.
var defaultValue = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().Single()
.DescendantNodes().OfType<EqualsValueClauseSyntax>().Single().Value;
var defaultValueModel = model.GetMemberModel(defaultValue);
Assert.Same(model, defaultValueModel.ContainingPublicModelOrSelf);
// Ensure binder chain is shared with member model for the enclosing method body.
var methodSyntax = (MethodDeclarationSyntax)comp.GetMember<MethodSymbol>("C.M").GetNonNullSyntaxNode();
var methodModel = model.GetMemberModel(methodSyntax.Body);
Assert.NotNull(methodModel);
var methodBinder = getBinder<BlockBinder>(methodModel.GetEnclosingBinder(methodSyntax.Body.SpanStart));
var defaultValueBinder = getBinder<BlockBinder>(defaultValueModel.GetEnclosingBinder(defaultValue.SpanStart));
Assert.Same(methodBinder, defaultValueBinder);
static T getBinder<T>(Binder binder) where T : Binder
{
while (true)
{
if (binder is T t)
{
return t;
}
binder = binder.NextRequired;
}
}
}
[Fact]
public void LambdaWithDefaultParameter_BindingScope()
{
var source = """
#nullable enable
class C<T> {
public static void M() {
var lam = (int a,
string b = nameof(a), // 1
string c = nameof(lam), // 2
string d = nameof(M),
string e = nameof(C<T>),
T? f = default(T),
C<T>? g = default(C<T>)
) => { };
lam(1);
}
}
""";
CreateCompilation(source).VerifyDiagnostics(
// (5,31): error CS0103: The name 'a' does not exist in the current context
// string b = nameof(a), // 1
Diagnostic(ErrorCode.ERR_NameNotInContext, "a").WithArguments("a").WithLocation(5, 31),
// (6,31): error CS0841: Cannot use local variable 'lam' before it is declared
// string c = nameof(lam), // 2
Diagnostic(ErrorCode.ERR_VariableUsedBeforeDeclaration, "lam").WithArguments("lam").WithLocation(6, 31));
}
[Fact]
public void LambdaWithDefaultParameter_LookupNames()
{
var source = """
class C<T1> {
private const int N1 = 10;
private int x;
private void M1() { }
public static void M2<T2>() {
const int N2 = 20;
int y = 2;
var lam = (int a, int b = /*pos*/5, int c = 6) => { };
lam(1);
}
}
""";
var tree = Parse(source);
var comp = CreateCompilation(tree);
var model = comp.GetSemanticModel(tree);
var names = model.LookupNames(GetPositionForBinding(source));
Assert.Contains("C", names);
Assert.Contains("x", names);
Assert.Contains("y", names);
Assert.Contains("N1", names);
Assert.Contains("N2", names);
Assert.Contains("T1", names);
Assert.Contains("T2", names);
Assert.Contains("M1", names);
Assert.Contains("M2", names);
Assert.Contains("lam", names);
Assert.DoesNotContain("a", names);
Assert.DoesNotContain("b", names);
Assert.DoesNotContain("c", names);
}
[Fact]
public void ParamsArray_Langversion()
{
var source = """
var lam = (params int[] xs) => xs.Length;
""";
CreateCompilation(source, parseOptions: TestOptions.Regular11).VerifyDiagnostics(
// (1,12): error CS9058: Feature 'lambda params array' is not available in C# 11.0. Please use language version 12.0 or greater.
// var lam = (params int[] xs) => xs.Length;
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "params").WithArguments("lambda params array", "12.0").WithLocation(1, 12));
CreateCompilation(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics();
}
[Theory]
[InlineData(LanguageVersion.CSharp11)]
[InlineData(LanguageVersion.CSharp12)]
public void ParamsArray_Langversion_DelegateSyntax(LanguageVersion languageVersion)
{
var source = """
var lam = delegate (params int[] xs) { return xs.Length; };
""";
CreateCompilation(source, parseOptions: TestOptions.Regular.WithLanguageVersion(languageVersion)).VerifyDiagnostics(
// (1,21): error CS1670: params is not valid in this context
// var lam = delegate (params int[] xs) { return xs.Length };
Diagnostic(ErrorCode.ERR_IllegalParams, "params").WithLocation(1, 21));
}
[Fact]
public void ParamsArray_Call()
{
var source = """
var lam = (params int?[] xs) => System.Console.WriteLine(xs?.Length.ToString() ?? "null");
lam();
lam(1);
lam(1, 2, 3);
lam(new int?[] { 1, 2, 3 });
lam(null);
lam((int?)null);
""";
CompileAndVerify(source, expectedOutput: """
0
1
3
3
null
1
""").VerifyDiagnostics();
}
[Fact]
public void ParamsArray_WithDefaultValue()
{
var source = """
var lam = (params int[] xs = null) => xs.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS1751: Cannot specify a default value for a parameter collection
// var lam = (params int[] xs = null) => xs.Length;
Diagnostic(ErrorCode.ERR_DefaultValueForParamsParameter, "params").WithLocation(1, 12));
}
[Fact]
public void ParamsArray_ParamArrayAttribute()
{
var source = """
var lam = ([System.ParamArray] int[] xs) => xs.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,13): error CS0674: Do not use 'System.ParamArrayAttribute'/'System.Runtime.CompilerServices.ParamCollectionAttribute'. Use the 'params' keyword instead.
// var lam = ([System.ParamArray] int[] xs) => xs.Length;
Diagnostic(ErrorCode.ERR_ExplicitParamArrayOrCollection, "System.ParamArray").WithLocation(1, 13));
}
[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/66060")]
public void ParamsArray_ParamArrayAttribute_OverloadResolution()
{
var source = """
using System;
new C().M(([ParamArray] int[] xs) => xs.Length);
new C().M((params int[] xs) => xs.Length);
class C
{
public void M(D d) { }
public void M(Func<int[], int> f) { }
}
delegate int D(params int[] xs);
""";
CreateCompilation(source).VerifyDiagnostics(
// (3,9): error CS0121: The call is ambiguous between the following methods or properties: 'C.M(D)' and 'C.M(Func<int[], int>)'
// new C().M(([ParamArray] int[] xs) => xs.Length);
Diagnostic(ErrorCode.ERR_AmbigCall, "M").WithArguments("C.M(D)", "C.M(System.Func<int[], int>)").WithLocation(3, 9),
// (4,9): error CS0121: The call is ambiguous between the following methods or properties: 'C.M(D)' and 'C.M(Func<int[], int>)'
// new C().M((params int[] xs) => xs.Length);
Diagnostic(ErrorCode.ERR_AmbigCall, "M").WithArguments("C.M(D)", "C.M(System.Func<int[], int>)").WithLocation(4, 9));
}
[Fact]
public void ParamsArray_Symbol()
{
var source = """
var lam1 = (params int[] xs) => xs.Length;
var lam2 = (int[] xs) => xs.Length;
var lam3 = (int[] xs, params int[] ys) => xs.Length + ys.Length;
""";
var comp = CreateCompilation(source).VerifyDiagnostics();
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.Equal(3, lambdas.Length);
// lam1
Assert.True(((SourceParameterSymbol)lambdas[0].Parameters.Single()).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[0].Parameters.Single()).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[0].Parameters.Single()).IsParamsCollection);
// lam2
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters.Single()).IsParams);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters.Single()).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters.Single()).IsParamsCollection);
// lam3
Assert.Equal(2, lambdas[2].ParameterCount);
Assert.Equal(2, lambdas[2].Parameters.Length);
Assert.False(((SourceParameterSymbol)lambdas[2].Parameters[0]).IsParams);
Assert.False(((SourceParameterSymbol)lambdas[2].Parameters[0]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[2].Parameters[0]).IsParamsCollection);
Assert.True(((SourceParameterSymbol)lambdas[2].Parameters[1]).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[2].Parameters[1]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[2].Parameters[1]).IsParamsCollection);
}
[Fact]
public void ParamsArray_Symbol_MultipleParamsArrays()
{
var source = """
var lam1 = (params int[] xs, params int[] ys, int[] zs) => xs.Length + ys.Length + zs.Length;
var lam2 = (params int[] xs, int[] ys, params int[] zs) => xs.Length + ys.Length + zs.Length;
""";
var comp = CreateCompilation(source);
var tree = comp.SyntaxTrees[0];
var model = comp.GetSemanticModel(tree);
var exprs = tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>().ToImmutableArray();
var lambdas = exprs.SelectAsArray(e => GetLambdaSymbol(model, e));
Assert.Equal(2, lambdas.Length);
// lam1
Assert.Equal(3, lambdas[0].ParameterCount);
Assert.Equal(3, lambdas[0].Parameters.Length);
Assert.True(((SourceParameterSymbol)lambdas[0].Parameters[0]).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[0].Parameters[0]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[0].Parameters[0]).IsParamsCollection);
Assert.True(((SourceParameterSymbol)lambdas[0].Parameters[1]).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[0].Parameters[1]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[0].Parameters[1]).IsParamsCollection);
Assert.False(((SourceParameterSymbol)lambdas[0].Parameters[2]).IsParams);
Assert.False(((SourceParameterSymbol)lambdas[0].Parameters[2]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[0].Parameters[2]).IsParamsCollection);
// lam2
Assert.Equal(3, lambdas[1].ParameterCount);
Assert.Equal(3, lambdas[1].Parameters.Length);
Assert.True(((SourceParameterSymbol)lambdas[1].Parameters[0]).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[1].Parameters[0]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters[0]).IsParamsCollection);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters[1]).IsParams);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters[1]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters[1]).IsParamsCollection);
Assert.True(((SourceParameterSymbol)lambdas[1].Parameters[2]).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[1].Parameters[2]).IsParamsArray);
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters[2]).IsParamsCollection);
}
[Fact]
public void ParamsArray_Symbol_ExternalReference()
{
var source = """
static void Report(object obj) => System.Console.WriteLine(obj.GetType());
var lam1 = (params int[] xs) => xs.Length;
Report(lam1);
var lam2 = (int[] xs) => xs.Length;
Report(lam2);
var lam3 = (int[] xs, params int[] ys) => xs.Length + ys.Length;
Report(lam3);
""";
CompileAndVerify(source, expectedOutput: """
<>f__AnonymousDelegate0`2[System.Int32,System.Int32]
System.Func`2[System.Int32[],System.Int32]
<>f__AnonymousDelegate1`3[System.Int32[],System.Int32,System.Int32]
""", symbolValidator: static module =>
{
var lam1 = (NamedTypeSymbol)module.GlobalNamespace.GetMember("<>f__AnonymousDelegate0");
Assert.True(lam1.DelegateParameters().Single().IsParams);
Assert.True(lam1.DelegateParameters().Single().IsParamsArray);
Assert.False(lam1.DelegateParameters().Single().IsParamsCollection);
AssertEx.Equal("TResult <>f__AnonymousDelegate0<T1, TResult>.Invoke(params T1[] arg)", lam1.DelegateInvokeMethod.ToTestDisplayString());
var lam3 = (NamedTypeSymbol)module.GlobalNamespace.GetMember("<>f__AnonymousDelegate1");
var lam3Parameters = lam3.DelegateParameters();
Assert.Equal(2, lam3Parameters.Length);
Assert.False(lam3Parameters[0].IsParams);
Assert.False(lam3Parameters[0].IsParamsArray);
Assert.False(lam3Parameters[0].IsParamsCollection);
Assert.True(lam3Parameters[1].IsParams);
Assert.True(lam3Parameters[1].IsParamsArray);
Assert.False(lam3Parameters[1].IsParamsCollection);
AssertEx.Equal("TResult <>f__AnonymousDelegate1<T1, T2, TResult>.Invoke(T1 arg1, params T2[] arg2)", lam3.DelegateInvokeMethod.ToTestDisplayString());
});
}
[Fact]
public void ParamsArray_NotLast()
{
var source = """
var lam = (params int[] xs, int y) => xs.Length + y;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0231: A params parameter must be the last parameter in a parameter list
// var lam = (params int[] xs, int y) => xs.Length + y;
Diagnostic(ErrorCode.ERR_ParamsLast, "params int[] xs").WithLocation(1, 12));
}
[Fact]
public void ParamsArray_Multiple()
{
var source = """
var lam = (params int[] xs, params int[] ys) => xs.Length + ys.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0231: A params parameter must be the last parameter in a parameter list
// var lam = (params int[] xs, params int[] ys) => xs.Length + ys.Length;
Diagnostic(ErrorCode.ERR_ParamsLast, "params int[] xs").WithLocation(1, 12));
}
[Fact]
public void ParamsArray_NotArray()
{
var source = """
var lam = (params int x) => x;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0225: The params parameter must have a valid collection type
// var lam = (params int x) => x;
Diagnostic(ErrorCode.ERR_ParamsMustBeCollection, "params").WithLocation(1, 12)
);
}
[Fact]
public void ParamsArray_Multidimensional()
{
var source = """
var lam = (params int[,] xs) => xs.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0225: The params parameter must have a valid collection type
// var lam = (params int[,] xs) => xs.Length;
Diagnostic(ErrorCode.ERR_ParamsMustBeCollection, "params").WithLocation(1, 12)
);
}
[Fact]
public void ParamsArray_Jagged()
{
var source = """
var lam = (params int[][] xs) => xs.Length;
""";
CreateCompilation(source).VerifyDiagnostics();
}
[Theory]
[InlineData("ref")]
[InlineData("out")]
[InlineData("in")]
public void ParamsArray_OtherModifiers(string modifier)
{
var source = $$"""
var lam = void (params {{modifier}} int[] xs) => throw null;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,24): error CS1611: The params parameter cannot be declared as ref
// var lam = void (params ref int[] xs) => throw null;
Diagnostic(ErrorCode.ERR_ParamsCantBeWithModifier, modifier).WithArguments(modifier).WithLocation(1, 24));
}
[Fact]
public void ParamsArray_ThisModifier_01()
{
var source = """
var lam = (this params int[] xs) => xs.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS1041: Identifier expected; 'this' is a keyword
// var lam = (this params int[] xs) => xs.Length;
Diagnostic(ErrorCode.ERR_IdentifierExpectedKW, "this").WithArguments("", "this").WithLocation(1, 12));
}
[Fact]
public void ParamsArray_ThisModifier_02()
{
var source = """
var lam = (params this int[] xs) => xs.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,19): error CS0027: Keyword 'this' is not available in the current context
// var lam = (params this int[] xs) => xs.Length;
Diagnostic(ErrorCode.ERR_ThisInBadContext, "this").WithLocation(1, 19));
}
}
}
|