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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.Linq;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;
namespace Microsoft.CodeAnalysis.CSharp.UnitTests.CodeGen
{
[CompilerTrait(CompilerFeature.AsyncStreams)]
public class CodeGenAwaitForeachTests : EmitMetadataTestBase
{
[Fact]
public void TestWithCSharp7_3()
{
string source = @"
using System.Collections.Generic;
class C : IAsyncEnumerable<int>
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (int i in new C())
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}";
var expected = new[]
{
// (7,9): error CS8652: The feature 'async streams' is not available in C# 7.3. Please use language version 8.0 or greater.
// await foreach (int i in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "await").WithArguments("async streams", "8.0").WithLocation(7, 9)
};
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(expected);
comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.Regular8);
comp.VerifyDiagnostics();
}
[Fact]
public void TestDeconstructionWithCSharp7_3()
{
string source = @"
using System.Collections.Generic;
class C : IAsyncEnumerable<(int, int)>
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var (i, j) in new C())
{
}
}
IAsyncEnumerator<(int, int)> IAsyncEnumerable<(int, int)>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}";
var expected = new[]
{
// (7,9): error CS8652: The feature 'async streams' is not available in C# 7.3. Please use language version 8.0 or greater.
// await foreach (int i in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "await").WithArguments("async streams", "8.0").WithLocation(7, 9)
};
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.Regular7_3);
comp.VerifyDiagnostics(expected);
comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.Regular8);
comp.VerifyDiagnostics();
}
[Fact]
public void TestWithMissingValueTask()
{
string lib_cs = @"
using System.Collections.Generic;
public class C : IAsyncEnumerable<int>
{
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}";
var lib = CreateCompilationWithTasksExtensions(new[] { lib_cs, s_IAsyncEnumerable });
lib.VerifyDiagnostics();
string source = @"
class D
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (int i in new C()) { }
}
}
";
var comp = CreateCompilationWithTasksExtensions(source, references: new[] { lib.EmitToImageReference() });
comp.MakeTypeMissing(WellKnownType.System_Threading_Tasks_ValueTask);
comp.VerifyDiagnostics(
// (6,9): error CS0518: Predefined type 'System.Threading.Tasks.ValueTask' is not defined or imported
// await foreach (int i in new C()) { }
Diagnostic(ErrorCode.ERR_PredefinedTypeNotFound, "await foreach (int i in new C()) { }").WithArguments("System.Threading.Tasks.ValueTask").WithLocation(6, 9)
);
}
[Fact]
public void TestWithIAsyncEnumerator()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
async Task M(IAsyncEnumerator<int> enumerator)
{
await foreach (int i in enumerator) { }
}
}
";
var comp_checked = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp_checked.VerifyDiagnostics(
// (8,33): error CS8411: Async foreach statement cannot operate on variables of type 'IAsyncEnumerator<int>' because 'IAsyncEnumerator<int>' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (int i in enumerator) { }
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "enumerator").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestWithUIntToIntConversion()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
public class C : IAsyncEnumerable<uint>
{
public static async Task Main()
{
try
{
REPLACE
{
await foreach (int i in new C()) { System.Console.Write($""0x{i:X8}""); }
}
}
catch (System.OverflowException)
{
System.Console.Write(""overflow"");
}
}
public IAsyncEnumerator<uint> GetAsyncEnumerator(System.Threading.CancellationToken token)
=> new AsyncEnumerator();
public sealed class AsyncEnumerator : IAsyncEnumerator<uint>
{
bool firstValue = true;
public uint Current => 0xFFFFFFFF;
public async ValueTask<bool> MoveNextAsync()
{
await Task.Yield();
bool result = firstValue;
firstValue = false;
return result;
}
public async ValueTask DisposeAsync()
{
await Task.Yield();
}
}
}
";
var comp_checked = CreateCompilationWithTasksExtensions(new[] { source.Replace("REPLACE", "checked"), s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp_checked.VerifyDiagnostics();
CompileAndVerify(comp_checked, expectedOutput: "overflow");
var comp_unchecked = CreateCompilationWithTasksExtensions(new[] { source.Replace("REPLACE", "unchecked"), s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp_unchecked.VerifyDiagnostics();
CompileAndVerify(comp_unchecked, expectedOutput: "0xFFFFFFFF");
}
[Fact]
public void TestWithTwoIAsyncEnumerableImplementations()
{
string source = @"
using System.Collections.Generic;
class C : IAsyncEnumerable<int>, IAsyncEnumerable<string>
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (int i in new C())
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
IAsyncEnumerator<string> IAsyncEnumerable<string>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (7,33): error CS8413: Async foreach statement cannot operate on variables of type 'C' because it implements multiple instantiations of 'IAsyncEnumerable<T>'; try casting to a specific interface instantiation
// await foreach (int i in new C())
Diagnostic(ErrorCode.ERR_MultipleIAsyncEnumOfT, "new C()").WithArguments("C", "System.Collections.Generic.IAsyncEnumerable<T>").WithLocation(7, 33)
);
}
[Fact]
public void TestWithMissingPattern()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8411: Async foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(6, 33)
);
}
[Fact]
public void TestWithStaticGetEnumerator()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public static Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw null;
}
public sealed class Enumerator
{
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8411: Async foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(6, 33)
);
}
[Fact]
public void TestWithInaccessibleGetEnumerator()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
internal Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
public sealed class Enumerator
{
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): warning CS0279: 'C' does not implement the 'async streams' pattern. 'C.GetAsyncEnumerator(System.Threading.CancellationToken)' is not a public instance or extension method.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternNotPublicOrNotInstance, "new C()").WithArguments("C", "async streams", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33),
// (6,33): error CS8411: Async foreach statement cannot operate on variables of type 'C' because 'C' does not contain a public definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(6, 33)
);
}
[Fact]
public void TestWithObsoletePatternMethods()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
[System.Obsolete]
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
public sealed class Enumerator
{
[System.Obsolete]
public System.Threading.Tasks.Task<bool> MoveNextAsync()
{
throw null;
}
[System.Obsolete]
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,15): warning CS0612: 'C.GetAsyncEnumerator(CancellationToken)' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 15),
// (6,15): warning CS0612: 'C.Enumerator.MoveNextAsync()' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.Enumerator.MoveNextAsync()").WithLocation(6, 15),
// (6,15): warning CS0612: 'C.Enumerator.Current' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.Enumerator.Current").WithLocation(6, 15)
);
}
[Fact]
public void TestWithMoveNextAsync_ReturnsValueTaskOfObject()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
public Enumerator GetAsyncEnumerator() => throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<object> MoveNextAsync() => throw null;
public int Current => throw null;
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator()").WithLocation(6, 33)
);
}
[Theory, CombinatorialData, WorkItem(65363, "https://github.com/dotnet/roslyn/issues/65363")]
public void TestWithMoveNextAsync_ReturnsValueTaskOfObject_Extension(bool useCsharp8)
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
}
static class Extension
{
public static Enumerator GetAsyncEnumerator(this C c) => throw null;
}
public sealed class Enumerator
{
public System.Threading.Tasks.Task<object> MoveNextAsync() => throw null;
public int Current => throw null;
}
";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: useCsharp8 ? TestOptions.Regular8 : TestOptions.Regular9);
if (useCsharp8)
{
comp.VerifyDiagnostics(
// (6,33): error CS8400: Feature 'extension GetAsyncEnumerator' is not available in C# 8.0. Please use language version 9.0 or greater.
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion8, "new C()").WithArguments("extension GetAsyncEnumerator", "9.0").WithLocation(6, 33),
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'Enumerator' of 'Extension.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("Enumerator", "Extension.GetAsyncEnumerator(C)").WithLocation(6, 33)
);
}
else
{
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'Enumerator' of 'Extension.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("Enumerator", "Extension.GetAsyncEnumerator(C)").WithLocation(6, 33)
);
}
}
[Fact]
public void TestWithMoveNextAsync_ReturnsObject()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator() => throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<object> MoveNextAsync() => throw null; // returns Task<object>
public int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator()").WithLocation(6, 33)
);
}
[Fact]
public void TestWithMoveNextAsync_Static()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
public sealed class Enumerator
{
public static System.Threading.Tasks.Task<bool> MoveNextAsync()
{
throw null;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
}
[Fact]
public void TestWithCurrent_Static()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
public Enumerator GetAsyncEnumerator()
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public static int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator()").WithLocation(6, 33)
);
}
[Fact]
public void TestWithMoveNextAsync_NonPublic()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
public Enumerator GetAsyncEnumerator()
=> throw null;
public sealed class Enumerator
{
internal System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current
=> throw null;
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator()").WithLocation(6, 33)
);
}
[Fact]
public void TestWithCurrent_NonPublicProperty()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
private int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS0122: 'C.Enumerator.Current' is inaccessible due to its protection level
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadAccess, "new C()").WithArguments("C.Enumerator.Current").WithLocation(6, 33),
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
}
[Fact]
public void TestWithCurrent_NonPublicGetter()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
public Enumerator GetAsyncEnumerator()
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current
{
private get => throw null;
set => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator()").WithLocation(6, 33)
);
}
[Fact]
public void TestWithCurrent_MissingGetter()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C()) { }
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current
{
set => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
}
[Fact]
public void TestWithCurrent_MissingGetterOnInterface()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task M(C c)
{
await foreach (var i in c)
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
System.Threading.Tasks.Task<bool> MoveNextAsync();
T Current { set; }
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'IAsyncEnumerator<int>' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "c").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(8, 33),
// (24,9): error CS1961: Invalid variance: The type parameter 'T' must be contravariantly valid on 'IAsyncEnumerator<T>.Current'. 'T' is covariant.
// T Current { set; }
Diagnostic(ErrorCode.ERR_UnexpectedVariance, "T").WithArguments("System.Collections.Generic.IAsyncEnumerator<T>.Current", "T", "covariant", "contravariantly").WithLocation(24, 9)
);
}
[Fact]
public void TestWithCurrent_MissingPropertyOnInterface()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task M(C c)
{
await foreach (var i in c)
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
System.Threading.Tasks.Task<bool> MoveNextAsync();
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS0117: 'IAsyncEnumerator<int>' does not contain a definition for 'Current'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_NoSuchMember, "c").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "Current").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'IAsyncEnumerator<int>' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "c").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(8, 33)
);
}
[Fact]
public void TestMoveNextAsync_ReturnsTask()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
public sealed class Enumerator
{
public System.Threading.Tasks.Task MoveNextAsync()
{
throw null;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
}
[Fact]
public void TestMoveNextAsync_ReturnsTaskOfInt()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
public sealed class Enumerator
{
public System.Threading.Tasks.Task<int> MoveNextAsync()
{
throw null;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
}
[Fact]
public void TestMoveNextAsync_WithOptionalParameter()
{
string source = @"
public class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new Enumerator();
}
public sealed class Enumerator
{
public async System.Threading.Tasks.Task<bool> MoveNextAsync(int ok = 1)
{
System.Console.Write($""MoveNextAsync {ok}"");
await System.Threading.Tasks.Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync 1");
}
[Fact]
public void TestMoveNextAsync_WithParamsParameter()
{
string source = @"
public class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new Enumerator();
}
public sealed class Enumerator
{
public async System.Threading.Tasks.Task<bool> MoveNextAsync(params int[] ok)
{
System.Console.Write($""MoveNextAsync {ok.Length}"");
await System.Threading.Tasks.Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync 0");
}
[Fact]
public void TestMoveNextAsync_Missing()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task M(C c)
{
await foreach (var i in c)
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
T Current { get; }
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS0117: 'IAsyncEnumerator<int>' does not contain a definition for 'MoveNextAsync'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_NoSuchMember, "c").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "MoveNextAsync").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'IAsyncEnumerator<int>' of 'C.GetAsyncEnumerator(CancellationToken)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "c").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(8, 33)
);
}
[Fact]
public void TestWithNonConvertibleElementType()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (string i in new C())
{
}
}
public Enumerator GetAsyncEnumerator()
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,15): error CS0030: Cannot convert type 'int' to 'string'
// await foreach (string i in new C())
Diagnostic(ErrorCode.ERR_NoExplicitConv, "foreach").WithArguments("int", "string").WithLocation(6, 15)
);
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.True(info.IsAsynchronous);
Assert.Equal("C.Enumerator C.GetAsyncEnumerator()", info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.Task<System.Boolean> C.Enumerator.MoveNextAsync()", info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 C.Enumerator.Current { get; }", info.CurrentProperty.ToTestDisplayString());
Assert.Null(info.DisposeMethod);
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.NoConversion, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
}
[Fact]
public void TestWithNonConvertibleElementType2()
{
string source = @"
using System.Threading.Tasks;
class C
{
async Task M()
{
await foreach (Element i in new C())
{
}
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class AsyncEnumerator
{
public int Current
{
get => throw null;
}
public Task<bool> MoveNextAsync()
=> throw null;
public ValueTask DisposeAsync()
=> throw null;
}
}
class Element
{
}";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyDiagnostics(
// (7,15): error CS0030: Cannot convert type 'int' to 'Element'
// await foreach (Element i in new C())
Diagnostic(ErrorCode.ERR_NoExplicitConv, "foreach").WithArguments("int", "Element").WithLocation(7, 15)
);
}
[Fact]
public void TestWithExplicitlyConvertibleElementType()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (Element i in new C())
{
Write($""Got({i}) "");
}
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new AsyncEnumerator();
}
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
bool more = await Task.FromResult(i < 4);
return more;
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}
class Element
{
int i;
public static explicit operator Element(int value) { Write($""Convert({value}) ""); return new Element(value); }
private Element(int value) { i = value; }
public override string ToString() => i.ToString();
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(1) Convert(1) Got(1) NextAsync(1) Current(2) Convert(2) Got(2) NextAsync(2) Current(3) Convert(3) Got(3) NextAsync(3) Dispose(4)");
}
[Fact]
public void TestWithCaptureOfIterationVariable()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async System.Threading.Tasks.Task Main()
{
System.Action f = null;
await foreach (var i in new C())
{
Write($""Got({i}) "");
if (f == null) f = () => Write($""Captured({i})"");
}
f();
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new AsyncEnumerator();
}
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
int i = 0;
public int Current => i;
public async Task<bool> MoveNextAsync()
{
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "Got(1) Got(2) Captured(1)");
}
[Fact]
public void TestWithGenericIterationVariable()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
class IntContainer
{
public int Value { get; set; }
}
public class Program
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C<IntContainer>())
{
Write($""Got({i.Value}) "");
}
}
}
class C<T> where T : IntContainer, new()
{
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new AsyncEnumerator();
}
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
int i = 0;
public T Current
{
get
{
Write($""Current({i}) "");
var result = new T();
((IntContainer)result).Value = i;
return result;
}
}
public async Task<bool> MoveNextAsync()
{
i++;
Write($""NextAsync({i}) "");
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(1) Current(1) Got(1) NextAsync(2) Current(2) Got(2) NextAsync(3) Current(3) Got(3) NextAsync(4) Dispose(4)");
}
[Fact]
public void TestWithThrowingGetAsyncEnumerator()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
try
{
await foreach (var i in new C())
{
throw null;
}
throw null;
}
catch (System.ArgumentException e)
{
Write(e.Message);
}
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw new System.ArgumentException(""exception"");
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
public int Current
=> throw null;
public Task<bool> MoveNextAsync()
=> throw null;
public ValueTask DisposeAsync()
=> throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "exception");
}
[Fact]
public void TestWithThrowingMoveNextAsync()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
try
{
await foreach (var i in new C())
{
throw null;
}
throw null;
}
catch (System.ArgumentException e)
{
Write(e.Message);
}
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> new AsyncEnumerator();
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
public int Current
=> throw null;
public Task<bool> MoveNextAsync()
=> throw new System.ArgumentException(""exception"");
public async ValueTask DisposeAsync()
{
Write(""dispose "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "dispose exception");
}
[Fact]
public void TestWithThrowingCurrent()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
try
{
await foreach (var i in new C())
{
throw null;
}
throw null;
}
catch (System.ArgumentException e)
{
Write(e.Message);
}
}
public AsyncEnumerator GetAsyncEnumerator()
=> new AsyncEnumerator();
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
public int Current
=> throw new System.ArgumentException(""exception"");
public async Task<bool> MoveNextAsync()
{
Write(""wait "");
await Task.Yield();
return true;
}
public async ValueTask DisposeAsync()
{
Write(""dispose "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "wait dispose exception");
}
[Fact]
public void TestWithThrowingDisposeAsync()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
try
{
await foreach (var i in new C())
{
throw null;
}
throw null;
}
catch (System.ArgumentException e)
{
Write(e.Message);
}
}
public AsyncEnumerator GetAsyncEnumerator()
=> new AsyncEnumerator();
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
public int Current => throw null;
public async Task<bool> MoveNextAsync()
{
Write(""wait "");
await Task.Yield();
return false;
}
public ValueTask DisposeAsync()
=> throw new System.ArgumentException(""exception"");
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "wait exception");
}
[Fact]
public void TestWithDynamicCollection()
{
string source = @"
class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var i in (dynamic)new C())
{
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (6,33): error CS8416: Cannot use a collection of dynamic type in an asynchronous foreach
// await foreach (var i in (dynamic)new C())
Diagnostic(ErrorCode.ERR_BadDynamicAwaitForEach, "(dynamic)new C()").WithLocation(6, 33));
}
[Fact]
public void TestWithIncompleteInterface()
{
string source = @"
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
}
}
class C
{
async System.Threading.Tasks.Task M(System.Collections.Generic.IAsyncEnumerable<int> collection)
{
await foreach (var i in collection)
{
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (12,33): error CS8411: Async foreach statement cannot operate on variables of type 'IAsyncEnumerable<int>' because 'IAsyncEnumerable<int>' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "collection").WithArguments("System.Collections.Generic.IAsyncEnumerable<int>", "GetAsyncEnumerator").WithLocation(12, 33)
);
}
[Fact]
public void TestWithIncompleteInterface2()
{
string source = @"
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IAsyncEnumerator<out T>
{
System.Threading.Tasks.Task<bool> MoveNextAsync();
}
}
class C
{
async System.Threading.Tasks.Task M(System.Collections.Generic.IAsyncEnumerable<int> collection)
{
await foreach (var i in collection)
{
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (18,33): error CS0117: 'IAsyncEnumerator<int>' does not contain a definition for 'Current'
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_NoSuchMember, "collection").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "Current").WithLocation(18, 33),
// (18,33): error CS8412: Async foreach requires that the return type 'IAsyncEnumerator<int>' of 'IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken)' must have a suitable public MoveNextAsync method and public Current property
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "collection").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "System.Collections.Generic.IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(18, 33)
);
}
[Fact]
public void TestWithIncompleteInterface3()
{
string source = @"
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IAsyncEnumerator<out T>
{
T Current { get; }
}
}
class C
{
async System.Threading.Tasks.Task M(System.Collections.Generic.IAsyncEnumerable<int> collection)
{
await foreach (var i in collection)
{
}
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (18,33): error CS0117: 'IAsyncEnumerator<int>' does not contain a definition for 'MoveNextAsync'
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_NoSuchMember, "collection").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "MoveNextAsync").WithLocation(18, 33),
// (18,33): error CS8412: Async foreach requires that the return type 'IAsyncEnumerator<int>' of 'IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken)' must have a suitable public MoveNextAsync method and public Current property
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "collection").WithArguments("System.Collections.Generic.IAsyncEnumerator<int>", "System.Collections.Generic.IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(18, 33)
);
}
[Fact]
public void TestWithSyncPattern()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetEnumerator()
{
throw null;
}
public sealed class Enumerator
{
bool MoveNext() => throw null;
int Current => throw null;
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,33): error CS8411: Async foreach statement cannot operate on variables of type 'C' because 'C' does not contain a public definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(6, 33)
);
}
[Fact]
public void TestRegularForeachWithAsyncPattern()
{
string source = @"
class C
{
void M()
{
foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync() => throw null;
public int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (6,27): error CS8414: foreach statement cannot operate on variables of type 'C' because 'C' does not contain a public instance or extension definition for 'GetEnumerator'. Did you mean 'await foreach' rather than 'foreach'?
// foreach (var i in new C())
Diagnostic(ErrorCode.ERR_ForEachMissingMemberWrongAsync, "new C()").WithArguments("C", "GetEnumerator").WithLocation(6, 27)
);
}
[Fact]
public void TestRegularForeachWithAsyncInterface()
{
string source = @"
using System.Collections.Generic;
class C
{
void M(IAsyncEnumerable<int> collection)
{
foreach (var i in collection)
{
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (7,27): error CS8414: foreach statement cannot operate on variables of type 'IAsyncEnumerable<int>' because 'IAsyncEnumerable<int>' does not contain a public instance or extension definition for 'GetEnumerator'. Did you mean 'await foreach'?
// foreach (var i in collection)
Diagnostic(ErrorCode.ERR_ForEachMissingMemberWrongAsync, "collection").WithArguments("System.Collections.Generic.IAsyncEnumerable<int>", "GetEnumerator").WithLocation(7, 27)
);
}
[Fact]
public void TestWithSyncInterfaceInRegularMethod()
{
string source = @"
using System.Collections.Generic;
class C
{
void M(IEnumerable<int> collection)
{
await foreach (var i in collection)
{
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (7,9): 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'.
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_BadAwaitWithoutVoidAsyncMethod, "await").WithLocation(7, 9),
// (7,33): error CS8415: Asynchronous foreach statement cannot operate on variables of type 'IEnumerable<int>' because 'IEnumerable<int>' does not contain a public instance or extension definition for 'GetAsyncEnumerator'. Did you mean 'foreach' rather than 'await foreach'?
// await foreach (var i in collection)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMemberWrongAsync, "collection").WithArguments("System.Collections.Generic.IEnumerable<int>", "GetAsyncEnumerator").WithLocation(7, 33)
);
}
[Fact]
public void TestPatternBasedAsyncEnumerableWithRegularForeach()
{
string source = @"
class C
{
void M()
{
foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,27): error CS8414: foreach statement cannot operate on variables of type 'C' because 'C' does not contain a public instance or extension definition for 'GetEnumerator'. Did you mean 'await foreach'?
// foreach (var i in new C())
Diagnostic(ErrorCode.ERR_ForEachMissingMemberWrongAsync, "new C()").WithArguments("C", "GetEnumerator").WithLocation(6, 27)
);
}
[Fact]
public void TestPatternBased_GetEnumeratorWithoutCancellationToken()
{
string source = @"
public class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator() // no parameter
=> new Enumerator();
public sealed class Enumerator
{
public async System.Threading.Tasks.Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync"");
await System.Threading.Tasks.Task.Yield();
return false;
}
public int Current => throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync");
}
[Fact]
public void TestPatternBasedEnumerableWithAwaitForeach()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator<int> GetEnumerator()
=> throw null;
public class Enumerator<T>
{
public T Current { get; }
public bool MoveNext()
=> throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,33): error CS8415: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a public instance or extension definition for 'GetAsyncEnumerator'. Did you mean 'foreach' rather than 'await foreach'?
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMemberWrongAsync, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(6, 33)
);
}
[Fact]
public void TestWithPattern()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
{
throw null;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("C.Enumerator C.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])", info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.Task<System.Boolean> C.Enumerator.MoveNextAsync()", info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 C.Enumerator.Current { get; }", info.CurrentProperty.ToTestDisplayString());
Assert.Null(info.DisposeMethod);
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
BoundForEachStatement boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.False(internalInfo.NeedsDisposal);
}
[Fact]
public void TestWithPattern_Ref()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (ref var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current { get => throw null; }
}
}" + s_IAsyncEnumerable;
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12);
comp.VerifyDiagnostics(
// (6,32): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (ref var i in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "i").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 32));
var expectedDiagnostics = new[]
{
// (6,37): error CS1510: A ref or out value must be an assignable variable
// await foreach (ref var i in new C())
Diagnostic(ErrorCode.ERR_RefLvalueExpected, "new C()").WithLocation(6, 37)
};
comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13);
comp.VerifyDiagnostics(expectedDiagnostics);
comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyDiagnostics(expectedDiagnostics);
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
Assert.Equal(default, model.GetForEachStatementInfo(foreachSyntax));
}
[Theory, CombinatorialData]
public void TestWithPattern_Ref_Iterator([CombinatorialValues(" ", "readonly")] string modifier)
{
var source = $$"""
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (int i in F())
{
Console.Write(i);
}
}
static async IAsyncEnumerable<int> F()
{
await foreach (ref {{modifier}} var i in new C())
{
yield return i;
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default) => new();
public sealed class Enumerator
{
private readonly int[] _array = [1, 2, 3];
private int _index = -1;
public Task<bool> MoveNextAsync()
{
if (_index < _array.Length) _index++;
return Task.FromResult(_index < _array.Length);
}
public ref int Current => ref _array[_index];
}
}
""" + AsyncStreamsTypes;
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12);
comp.VerifyDiagnostics(
// (17,41): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (ref readonly var i in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "i").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(17, 41));
var expectedOutput = "123";
comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe, parseOptions: TestOptions.Regular13);
CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();
comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_Ref_Iterator_Used()
{
var source = """
using System.Collections.Generic;
using System.Threading.Tasks;
class C
{
static async IAsyncEnumerable<int> F()
{
await foreach (ref var i in new C())
{
yield return i;
M(ref i);
}
}
static void M(ref int i) { }
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default) => new();
public sealed class Enumerator
{
private readonly int[] _array = [1, 2, 3];
private int _index = -1;
public Task<bool> MoveNextAsync()
{
if (_index < _array.Length) _index++;
return Task.FromResult(_index < _array.Length);
}
public ref int Current => ref _array[_index];
}
}
""" + AsyncStreamsTypes;
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12);
comp.VerifyDiagnostics(
// (8,32): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (ref var i in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "i").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(8, 32));
var expectedDiagnostics = new[]
{
// (11,19): error CS9217: A 'ref' local cannot be preserved across 'await' or 'yield' boundary.
// M(ref i);
Diagnostic(ErrorCode.ERR_RefLocalAcrossAwait, "i").WithLocation(11, 19)
};
comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13);
comp.VerifyEmitDiagnostics(expectedDiagnostics);
comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(expectedDiagnostics);
}
[Fact]
public void TestWithPattern_PointerType()
{
string source = @"
unsafe class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync() => throw null;
public int* Current { get => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.UnsafeDebugDll);
comp.VerifyDiagnostics(
// (6,9): error CS4004: Cannot await in an unsafe context
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitInUnsafeContext, "await").WithLocation(6, 9));
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
Assert.Equal(default, model.GetForEachStatementInfo(foreachSyntax));
}
[Fact]
public void TestWithPattern_InaccessibleGetAsyncEnumerator()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new D())
{
}
}
}
class D
{
private Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,33): error CS8411: Async foreach statement cannot operate on variables of type 'D' because 'D' does not contain a public definition for 'GetAsyncEnumerator'
// await foreach (var i in new D())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new D()").WithArguments("D", "GetAsyncEnumerator").WithLocation(6, 33)
);
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
Assert.Equal(default, model.GetForEachStatementInfo(foreachSyntax));
}
[Fact]
public void TestWithPattern_InaccessibleMoveNextAsync()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new D())
{
}
}
}
class D
{
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
private System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,33): error CS0122: 'D.Enumerator.MoveNextAsync()' is inaccessible due to its protection level
// await foreach (var i in new D())
Diagnostic(ErrorCode.ERR_BadAccess, "new D()").WithArguments("D.Enumerator.MoveNextAsync()").WithLocation(6, 33),
// (6,33): error CS8412: Async foreach requires that the return type 'D.Enumerator' of 'D.GetAsyncEnumerator(System.Threading.CancellationToken)' must have a suitable public MoveNextAsync method and public Current property
// await foreach (var i in new D())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new D()").WithArguments("D.Enumerator", "D.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
Assert.Equal(default, model.GetForEachStatementInfo(foreachSyntax));
}
[Fact]
public void TestWithPattern_InaccessibleCurrent()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new D()) { }
}
}
class D
{
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync() => throw null;
private int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,33): error CS0122: 'D.Enumerator.Current' is inaccessible due to its protection level
// await foreach (var i in new D()) { }
Diagnostic(ErrorCode.ERR_BadAccess, "new D()").WithArguments("D.Enumerator.Current").WithLocation(6, 33),
// (6,33): error CS8412: Async foreach requires that the return type 'D.Enumerator' of 'D.GetAsyncEnumerator(System.Threading.CancellationToken)' must have a suitable public MoveNextAsync method and public Current property
// await foreach (var i in new D()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new D()").WithArguments("D.Enumerator", "D.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(6, 33)
);
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
Assert.Equal(default, model.GetForEachStatementInfo(foreachSyntax));
}
[Fact]
public void TestWithPattern_InaccessibleCurrentGetter()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new D()) { }
}
}
class D
{
public Enumerator GetAsyncEnumerator()
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync() => throw null;
public int Current { private get => throw null; set => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (6,33): error CS8412: Async foreach requires that the return type 'D.Enumerator' of 'D.GetAsyncEnumerator()' must have a suitable public MoveNextAsync method and public Current property
// await foreach (var i in new D()) { }
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new D()").WithArguments("D.Enumerator", "D.GetAsyncEnumerator()").WithLocation(6, 33)
);
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
Assert.Equal(default, model.GetForEachStatementInfo(foreachSyntax));
}
[Fact]
public void TestWithPattern_RefStruct()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var s in new C())
{
Write($""{s.ToString()} "");
}
Write(""Done"");
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator : System.IAsyncDisposable
{
int i = 0;
public int Current => i;
public async Task<bool> MoveNextAsync()
{
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
await Task.Yield();
}
}
}
public ref struct S
{
int i;
public S(int i)
{
this.i = i;
}
public override string ToString() => i.ToString();
}
";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "1 2 Done");
}
[Theory]
[InlineData("")]
[InlineData("await Task.Yield();")]
public void TestWithPattern_RefStructEnumerator_Async(string body)
{
var source = $$"""
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var s in new C())
{
{{body}}
}
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public ref struct Enumerator
{
public int Current => 0;
public Task<bool> MoveNextAsync() => throw null;
}
}
""";
CreateCompilation(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (6,15): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "foreach").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 15));
var expectedDiagnostics = new[]
{
// (6,9): error CS4007: Instance of type 'C.Enumerator' cannot be preserved across 'await' or 'yield' boundary.
// await foreach (var s in new C())
Diagnostic(ErrorCode.ERR_ByRefTypeAndAwait, @"await foreach (var s in new C())
{
" + body + @"
}").WithArguments("C.Enumerator").WithLocation(6, 9)
};
CreateCompilation(source, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics(expectedDiagnostics);
CreateCompilation(source).VerifyEmitDiagnostics(expectedDiagnostics);
}
[Theory]
[InlineData("")]
[InlineData("await Task.Yield();")]
[InlineData("yield return x;")]
[InlineData("yield return x; await Task.Yield();")]
[InlineData("await Task.Yield(); yield return x;")]
public void TestWithPattern_RefStructEnumerator_AsyncIterator(string body)
{
var source = $$"""
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
public static async IAsyncEnumerable<int> M()
{
await foreach (var x in new C())
{
{{body}}
}
yield return -1;
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public ref struct Enumerator
{
public int Current => 0;
public Task<bool> MoveNextAsync() => throw null;
}
}
""" + AsyncStreamsTypes;
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (7,15): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (var x in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "foreach").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 15));
var expectedDiagnostics = new[]
{
// (7,9): error CS4007: Instance of type 'C.Enumerator' cannot be preserved across 'await' or 'yield' boundary.
// await foreach (var x in new C())
Diagnostic(ErrorCode.ERR_ByRefTypeAndAwait, @"await foreach (var x in new C())
{
" + body + @"
}").WithArguments("C.Enumerator").WithLocation(7, 9)
};
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics(expectedDiagnostics);
CreateCompilationWithTasksExtensions(source).VerifyEmitDiagnostics(expectedDiagnostics);
}
[Fact]
public void TestWithPattern_RefStructEnumerator_Iterator()
{
var source = """
using System.Collections.Generic;
public class C
{
public static IEnumerable<int> M()
{
foreach (var x in new C())
{
yield return x;
}
}
public Enumerator GetEnumerator() => new Enumerator();
public ref struct Enumerator
{
public int Current => 0;
public bool MoveNext() => throw null;
}
}
""";
CreateCompilation(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (6,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// foreach (var x in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "foreach").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 9));
var expectedDiagnostics = new[]
{
// (6,9): error CS4007: Instance of type 'C.Enumerator' cannot be preserved across 'await' or 'yield' boundary.
// foreach (var x in new C())
Diagnostic(ErrorCode.ERR_ByRefTypeAndAwait, @"foreach (var x in new C())
{
yield return x;
}").WithArguments("C.Enumerator").WithLocation(6, 9)
};
CreateCompilation(source, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics(expectedDiagnostics);
CreateCompilation(source).VerifyEmitDiagnostics(expectedDiagnostics);
}
[Fact]
public void TestWithPattern_RefStructEnumerable_Async()
{
var source = """
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var x in new Enumerable())
{
await Task.Yield();
Console.Write($"{x} ");
}
Console.Write("Done");
}
public ref struct Enumerable
{
public Enumerator GetAsyncEnumerator() => new();
}
public class Enumerator
{
int i = 0;
public int Current => i;
public async Task<bool> MoveNextAsync()
{
i++;
await Task.Yield();
return i < 3;
}
}
}
""" + s_IAsyncEnumerable;
var comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: "1 2 Done").VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefStructEnumerable_AsyncIterator()
{
var source = """
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in M())
{
Console.Write($"{i} ");
}
Console.Write("Done");
}
public static async IAsyncEnumerable<int> M()
{
await foreach (var x in new Enumerable())
{
await Task.Yield();
yield return x * 2;
}
yield return -1;
}
public ref struct Enumerable
{
public Enumerator GetAsyncEnumerator() => new();
}
public class Enumerator
{
int i = 0;
public int Current => i;
public async Task<bool> MoveNextAsync()
{
i++;
await Task.Yield();
return i < 3;
}
}
}
""" + AsyncStreamsTypes;
var comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: "2 4 -1 Done").VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefStructEnumerable_Iterator()
{
var source = """
using System;
using System.Collections.Generic;
public class C
{
public static void Main()
{
foreach (var i in M())
{
Console.Write($"{i} ");
}
Console.Write("Done");
}
public static IEnumerable<int> M()
{
foreach (var x in new Enumerable())
{
yield return x * 2;
}
yield return -1;
}
public ref struct Enumerable
{
public Enumerator GetEnumerator() => new();
}
public class Enumerator
{
int i = 0;
public int Current => i;
public bool MoveNext()
{
i++;
return i < 3;
}
}
}
""";
CompileAndVerify(source, expectedOutput: "2 4 -1 Done").VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefStructCurrent_Async()
{
var source = """
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var s in new C())
{
Console.Write($"{s.ToString()} ");
}
Console.Write("Done");
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator : IAsyncDisposable
{
int i = 0;
public S Current => new S(i);
public async Task<bool> MoveNextAsync()
{
i++;
await Task.Yield();
return i < 3;
}
public async ValueTask DisposeAsync()
{
await Task.Yield();
}
}
}
public ref struct S
{
int i;
public S(int i)
{
this.i = i;
}
public override string ToString() => i.ToString();
}
""" + s_IAsyncEnumerable;
var expectedDiagnostics = new[]
{
// (7,24): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "var").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 24)
};
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expectedDiagnostics);
var expectedOutput = "1 2 Done";
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefStructCurrent_AsyncIterator()
{
var source = """
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var s in M())
{
Console.Write($"M:{s} ");
}
Console.Write("MainDone");
}
public static async IAsyncEnumerable<string> M()
{
await foreach (var s in new C())
{
yield return s.ToString();
}
yield return "Done";
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator : IAsyncDisposable
{
int i = 0;
public S Current => new S(i);
public async Task<bool> MoveNextAsync()
{
i++;
await Task.Yield();
return i < 3;
}
public async ValueTask DisposeAsync()
{
await Task.Yield();
}
}
}
public ref struct S
{
int i;
public S(int i)
{
this.i = i;
}
public override string ToString() => i.ToString();
}
""" + AsyncStreamsTypes;
var expectedDiagnostics = new[]
{
// (16,24): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "var").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(16, 24)
};
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expectedDiagnostics);
var expectedOutput = "M:1 M:2 M:Done MainDone";
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefStructCurrent_Iterator()
{
var source = """
using System;
using System.Collections.Generic;
public class C
{
public static void Main()
{
foreach (var s in M())
{
Console.Write($"M:{s} ");
}
Console.Write("MainDone");
}
public static IEnumerable<string> M()
{
foreach (var s in new C())
{
yield return s.ToString();
}
yield return "Done";
}
public Enumerator GetEnumerator() => new Enumerator();
public sealed class Enumerator
{
int i = 0;
public S Current => new S(i);
public bool MoveNext()
{
i++;
return i < 3;
}
}
}
public ref struct S
{
int i;
public S(int i)
{
this.i = i;
}
public override string ToString() => i.ToString();
}
""";
var expectedOutput = "M:1 M:2 M:Done MainDone";
CompileAndVerify(source, parseOptions: TestOptions.Regular12, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
CompileAndVerify(source, parseOptions: TestOptions.Regular13, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
CompileAndVerify(source, expectedOutput: expectedOutput, verify: Verification.FailsILVerify).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefReturningCurrent_Async()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var s in new C())
{
Write($""{s.ToString()} "");
}
Write(""Done"");
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator
{
int i = 0;
S current;
public ref S Current
{
get
{
current = new S(i);
return ref current;
}
}
public async Task<bool> MoveNextAsync()
{
i++;
return await Task.FromResult(i < 4);
}
}
}
public struct S
{
int i;
public S(int i)
{
this.i = i;
}
public override string ToString()
=> i.ToString();
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "1 2 3 Done", verify: Verification.Fails);
}
[Fact]
public void TestWithPattern_RefReturningCurrent_Async_RefVariable()
{
string source = """
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (ref var s in new C())
{
Console.Write($"{s} ");
s.F++;
}
Console.Write("Done");
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator
{
S _current;
public ref S Current => ref _current;
public async Task<bool> MoveNextAsync()
{
Current = new S(Current.F + 1);
await Task.Yield();
return Current.F < 4;
}
}
}
public struct S
{
public int F;
public S(int i)
{
this.F = i;
}
public override string ToString() => F.ToString();
}
""" + s_IAsyncEnumerable;
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (7,32): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (ref var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "s").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 32));
var expectedOutput = "1 3 Done";
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();
comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefReturningCurrent_AsyncIterator_RefVariable_01()
{
string source = """
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var s in M())
{
Console.Write($"M:{s} ");
}
Console.Write("MainDone");
}
public static async IAsyncEnumerable<string> M()
{
await foreach (ref var s in new C())
{
s.F++;
yield return s.ToString();
}
yield return "Done";
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator
{
S _current;
public ref S Current => ref _current;
public async Task<bool> MoveNextAsync()
{
Current = new S(Current.F + 1);
await Task.Yield();
return Current.F < 4;
}
}
}
public struct S
{
public int F;
public S(int i)
{
this.F = i;
}
public override string ToString() => F.ToString();
}
""" + AsyncStreamsTypes;
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (16,32): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (ref var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "s").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(16, 32));
var expectedOutput = "M:2 M:4 M:Done MainDone";
var comp = CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();
comp = CreateCompilationWithTasksExtensions(source, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefReturningCurrent_AsyncIterator_RefVariable_02()
{
string source = """
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
public static async IAsyncEnumerable<string> M()
{
await foreach (ref var s in new C())
{
yield return s.ToString();
s.F++;
}
yield return "Done";
}
public Enumerator GetAsyncEnumerator() => new Enumerator();
public sealed class Enumerator
{
public ref S Current => throw null;
public Task<bool> MoveNextAsync() => throw null;
}
}
public struct S
{
public int F;
}
""" + AsyncStreamsTypes;
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (7,32): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// await foreach (ref var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "s").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 32));
var expectedDiagnostics = new[]
{
// (10,13): error CS9217: A 'ref' local cannot be preserved across 'await' or 'yield' boundary.
// s.F++;
Diagnostic(ErrorCode.ERR_RefLocalAcrossAwait, "s.F").WithLocation(10, 13)
};
CreateCompilationWithTasksExtensions(source, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics(expectedDiagnostics);
CreateCompilationWithTasksExtensions(source).VerifyEmitDiagnostics(expectedDiagnostics);
}
[Fact]
public void TestWithPattern_RefReturningCurrent_Iterator_RefVariable_01()
{
string source = """
using System;
using System.Collections.Generic;
public class C
{
public static void Main()
{
foreach (var s in M())
{
Console.Write($"M:{s} ");
}
Console.Write("MainDone");
}
public static IEnumerable<string> M()
{
foreach (ref var s in new C())
{
s.F++;
yield return s.ToString();
}
yield return "Done";
}
public Enumerator GetEnumerator() => new Enumerator();
public sealed class Enumerator
{
S _current;
public ref S Current => ref _current;
public bool MoveNext()
{
Current = new S(Current.F + 1);
return Current.F < 4;
}
}
}
public struct S
{
public int F;
public S(int i)
{
this.F = i;
}
public override string ToString() => F.ToString();
}
""";
CreateCompilation(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (15,26): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// foreach (ref var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "s").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(15, 26));
var expectedOutput = "M:2 M:4 M:Done MainDone";
CompileAndVerify(source, parseOptions: TestOptions.Regular13, expectedOutput: expectedOutput).VerifyDiagnostics();
CompileAndVerify(source, expectedOutput: expectedOutput).VerifyDiagnostics();
}
[Fact]
public void TestWithPattern_RefReturningCurrent_Iterator_RefVariable_02()
{
string source = """
using System.Collections.Generic;
public class C
{
public static IEnumerable<string> M()
{
foreach (ref var s in new C())
{
yield return s.ToString();
s.F++;
}
yield return "Done";
}
public Enumerator GetEnumerator() => new Enumerator();
public sealed class Enumerator
{
public ref S Current => throw null;
public bool MoveNext() => throw null;
}
}
public struct S
{
public int F;
}
""";
CreateCompilation(source, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
// (6,26): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
// foreach (ref var s in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "s").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 26));
var expectedDiagnostics = new[]
{
// (9,13): error CS9217: A 'ref' local cannot be preserved across 'await' or 'yield' boundary.
// s.F++;
Diagnostic(ErrorCode.ERR_RefLocalAcrossAwait, "s.F").WithLocation(9, 13)
};
CreateCompilation(source, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics(expectedDiagnostics);
CreateCompilation(source).VerifyEmitDiagnostics(expectedDiagnostics);
}
[Fact]
public void TestWithPattern_IterationVariableIsReadOnly()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
i = 1;
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
=> throw null;
public sealed class Enumerator
{
public System.Threading.Tasks.Task<bool> MoveNextAsync()
=> throw null;
public int Current { get => throw null; }
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (8,13): error CS1656: Cannot assign to 'i' because it is a 'foreach iteration variable'
// i = 1;
Diagnostic(ErrorCode.ERR_AssgReadonlyLocalCause, "i").WithArguments("i", "foreach iteration variable").WithLocation(8, 13)
);
}
[Fact]
public void TestWithPattern_WithStruct_MoveNextAsyncReturnsTask()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
Write($""Done"");
}
public AsyncEnumerator GetAsyncEnumerator()
{
return new AsyncEnumerator(0);
}
public struct AsyncEnumerator
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
i++;
return i;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
bool more = await Task.FromResult(i < 4);
i = i + 100; // Note: side-effects of async methods in structs are lost
return more;
}
public async ValueTask DisposeAsync()
{
Write($""DisposeAsync "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(0) Got(1) NextAsync(1) Current(1) Got(2) NextAsync(2) Current(2) Got(3) NextAsync(3) Current(3) Got(4) NextAsync(4) DisposeAsync Done");
}
[Fact]
public void TestWithPattern_MoveNextAsyncReturnsValueTask()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
Write($""Done"");
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new AsyncEnumerator(0);
}
public class AsyncEnumerator : System.IAsyncDisposable
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4) Done");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> C.AsyncEnumerator.MoveNextAsync()", info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[Fact]
[WorkItem(31609, "https://github.com/dotnet/roslyn/issues/31609")]
public void TestWithPattern_MoveNextAsyncReturnsAwaitable()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
Write($""Item({i}) "");
break;
}
Write($""Done"");
}
public AsyncEnumerator GetAsyncEnumerator()
{
return new AsyncEnumerator();
}
public class AsyncEnumerator : System.IAsyncDisposable
{
public int Current => 1;
public Awaitable MoveNextAsync()
{
return new Awaitable();
}
public async ValueTask DisposeAsync()
{
Write(""Dispose "");
await Task.Yield();
}
}
public class Awaitable
{
public Awaiter GetAwaiter() { return new Awaiter(); }
}
public class Awaiter : System.Runtime.CompilerServices.INotifyCompletion
{
public bool IsCompleted { get { return true; } }
public bool GetResult() { return true; }
public void OnCompleted(System.Action continuation) { }
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "Item(1) Dispose Done");
var tree = comp.SyntaxTrees.First();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("C.Awaitable C.AsyncEnumerator.MoveNextAsync()", info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
}
[Fact]
[WorkItem(31609, "https://github.com/dotnet/roslyn/issues/31609")]
public void TestWithPattern_MoveNextAsyncReturnsAwaitable_WithoutGetAwaiter()
{
string source = @"
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
}
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
public class AsyncEnumerator : System.IAsyncDisposable
{
public int Current => 1;
public Awaitable MoveNextAsync() => throw null;
public ValueTask DisposeAsync() => throw null;
}
public class Awaitable
{
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics(
// (7,33): error CS1061: 'C.Awaitable' does not contain a definition for 'GetAwaiter' and no accessible extension method 'GetAwaiter' accepting a first argument of type 'C.Awaitable' could be found (are you missing a using directive or an assembly reference?)
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMemberOrExtension, "new C()").WithArguments("C.Awaitable", "GetAwaiter").WithLocation(7, 33)
);
VerifyEmptyForEachStatementInfo(comp);
}
[Fact]
[WorkItem(31609, "https://github.com/dotnet/roslyn/issues/31609")]
public void TestWithPattern_MoveNextAsyncReturnsAwaitable_WithoutIsCompleted()
{
string source = @"
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
}
}
public AsyncEnumerator GetAsyncEnumerator() => throw null;
public class AsyncEnumerator : System.IAsyncDisposable
{
public int Current => 1;
public Awaitable MoveNextAsync() => throw null;
public ValueTask DisposeAsync() => throw null;
}
public class Awaitable
{
public Awaiter GetAwaiter() => throw null;
}
public class Awaiter : System.Runtime.CompilerServices.INotifyCompletion
{
public bool GetResult() { return true; }
public void OnCompleted(System.Action continuation) { }
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics(
// (7,33): error CS0117: 'C.Awaiter' does not contain a definition for 'IsCompleted'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("C.Awaiter", "IsCompleted").WithLocation(7, 33)
);
VerifyEmptyForEachStatementInfo(comp);
}
private static void VerifyEmptyForEachStatementInfo(CSharpCompilation comp)
{
var tree = comp.SyntaxTrees.First();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Null(info.MoveNextMethod);
Assert.Null(info.ElementType);
}
[Fact]
[WorkItem(31609, "https://github.com/dotnet/roslyn/issues/31609")]
public void TestWithPattern_MoveNextAsyncReturnsAwaitable_WithoutGetResult()
{
string source = @"
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
}
}
public AsyncEnumerator GetAsyncEnumerator() => throw null;
public class AsyncEnumerator : System.IAsyncDisposable
{
public int Current => 1;
public Awaitable MoveNextAsync() => throw null;
public ValueTask DisposeAsync() => throw null;
}
public class Awaitable
{
public Awaiter GetAwaiter() => throw null;
}
public class Awaiter : System.Runtime.CompilerServices.INotifyCompletion
{
public bool IsCompleted { get { return true; } }
public void OnCompleted(System.Action continuation) { }
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics(
// (7,33): error CS1061: 'C.Awaiter' does not contain a definition for 'GetResult' and no accessible extension method 'GetResult' accepting a first argument of type 'C.Awaiter' could be found (are you missing a using directive or an assembly reference?)
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMemberOrExtension, "new C()").WithArguments("C.Awaiter", "GetResult").WithLocation(7, 33)
);
VerifyEmptyForEachStatementInfo(comp);
}
[Fact]
[WorkItem(31609, "https://github.com/dotnet/roslyn/issues/31609")]
public void TestWithPattern_MoveNextAsyncReturnsAwaitable_WithoutOnCompleted()
{
string source = @"
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
}
}
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
public class AsyncEnumerator : System.IAsyncDisposable
{
public int Current => 1;
public Awaitable MoveNextAsync() => throw null;
public ValueTask DisposeAsync() => throw null;
}
public class Awaitable
{
public Awaiter GetAwaiter() => throw null;
}
public class Awaiter
{
public bool IsCompleted { get { return true; } }
public bool GetResult() { return true; }
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics(
// (7,33): error CS4027: 'C.Awaiter' does not implement 'INotifyCompletion'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_DoesntImplementAwaitInterface, "new C()").WithArguments("C.Awaiter", "System.Runtime.CompilerServices.INotifyCompletion").WithLocation(7, 33)
);
VerifyEmptyForEachStatementInfo(comp);
}
[Fact]
public void TestWithPattern_MoveNextAsyncReturnsBadType()
{
string source = @"
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var i in new C())
{
}
}
public AsyncEnumerator GetAsyncEnumerator() => throw null;
public class AsyncEnumerator
{
public int Current => throw null;
public int MoveNextAsync() => throw null;
public ValueTask DisposeAsync() => throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (7,33): error CS1061: 'int' does not contain a definition for 'GetAwaiter' and no accessible extension method 'GetAwaiter' accepting a first argument of type 'int' could be found (are you missing a using directive or an assembly reference?)
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMemberOrExtension, "new C()").WithArguments("int", "GetAwaiter").WithLocation(7, 33)
);
var tree = comp.SyntaxTrees.First();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Null(info.MoveNextMethod);
Assert.Null(info.ElementType);
}
[Fact]
public void TestWithPattern_WithUnsealed()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public class Enumerator
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var memberModel = model.GetMemberModel(foreachSyntax);
BoundForEachStatement boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4)");
}
[ConditionalFact(typeof(WindowsDesktopOnly), Reason = ConditionalSkipReason.NativePdbRequiresDesktop)]
public void TestWithPattern_WithUnsealed_WithIAsyncDisposable()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
}
public Enumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new DerivedEnumerator();
}
public class Enumerator
{
protected int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
}
public class DerivedEnumerator : Enumerator, System.IAsyncDisposable
{
public ValueTask DisposeAsync() => throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.False(internalInfo.NeedsDisposal);
var verifier = CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3)");
verifier.VerifyIL("C.<Main>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext()", @"
{
// Code size 273 (0x111)
.maxstack 3
.locals init (int V_0,
System.Threading.CancellationToken V_1,
System.Runtime.CompilerServices.TaskAwaiter<bool> V_2,
C.<Main>d__0 V_3,
System.Exception V_4)
// sequence point: <hidden>
IL_0000: ldarg.0
IL_0001: ldfld ""int C.<Main>d__0.<>1__state""
IL_0006: stloc.0
.try
{
// sequence point: <hidden>
IL_0007: ldloc.0
IL_0008: brfalse.s IL_0012
IL_000a: br.s IL_000c
IL_000c: ldloc.0
IL_000d: ldc.i4.1
IL_000e: beq.s IL_0017
IL_0010: br.s IL_001c
IL_0012: br IL_00a5
IL_0017: br IL_00a5
// sequence point: {
IL_001c: nop
// sequence point: await foreach
IL_001d: nop
// sequence point: new C()
IL_001e: ldarg.0
IL_001f: newobj ""C..ctor()""
IL_0024: ldloca.s V_1
IL_0026: initobj ""System.Threading.CancellationToken""
IL_002c: ldloc.1
IL_002d: call ""C.Enumerator C.GetAsyncEnumerator(System.Threading.CancellationToken)""
IL_0032: stfld ""C.Enumerator C.<Main>d__0.<>s__1""
// sequence point: <hidden>
IL_0037: br.s IL_0067
// sequence point: var i
IL_0039: ldarg.0
IL_003a: ldarg.0
IL_003b: ldfld ""C.Enumerator C.<Main>d__0.<>s__1""
IL_0040: callvirt ""int C.Enumerator.Current.get""
IL_0045: stfld ""int C.<Main>d__0.<i>5__2""
// sequence point: {
IL_004a: nop
// sequence point: Write($""Got({i}) "");
IL_004b: ldstr ""Got({0}) ""
IL_0050: ldarg.0
IL_0051: ldfld ""int C.<Main>d__0.<i>5__2""
IL_0056: box ""int""
IL_005b: call ""string string.Format(string, object)""
IL_0060: call ""void System.Console.Write(string)""
IL_0065: nop
// sequence point: }
IL_0066: nop
// sequence point: in
IL_0067: ldarg.0
IL_0068: ldfld ""C.Enumerator C.<Main>d__0.<>s__1""
IL_006d: callvirt ""System.Threading.Tasks.Task<bool> C.Enumerator.MoveNextAsync()""
IL_0072: callvirt ""System.Runtime.CompilerServices.TaskAwaiter<bool> System.Threading.Tasks.Task<bool>.GetAwaiter()""
IL_0077: stloc.2
// sequence point: <hidden>
IL_0078: ldloca.s V_2
IL_007a: call ""bool System.Runtime.CompilerServices.TaskAwaiter<bool>.IsCompleted.get""
IL_007f: brtrue.s IL_00c1
IL_0081: ldarg.0
IL_0082: ldc.i4.0
IL_0083: dup
IL_0084: stloc.0
IL_0085: stfld ""int C.<Main>d__0.<>1__state""
// async: yield
IL_008a: ldarg.0
IL_008b: ldloc.2
IL_008c: stfld ""System.Runtime.CompilerServices.TaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_0091: ldarg.0
IL_0092: stloc.3
IL_0093: ldarg.0
IL_0094: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_0099: ldloca.s V_2
IL_009b: ldloca.s V_3
IL_009d: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<bool>, C.<Main>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<bool>, ref C.<Main>d__0)""
IL_00a2: nop
IL_00a3: leave.s IL_0110
// async: resume
IL_00a5: ldarg.0
IL_00a6: ldfld ""System.Runtime.CompilerServices.TaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00ab: stloc.2
IL_00ac: ldarg.0
IL_00ad: ldflda ""System.Runtime.CompilerServices.TaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00b2: initobj ""System.Runtime.CompilerServices.TaskAwaiter<bool>""
IL_00b8: ldarg.0
IL_00b9: ldc.i4.m1
IL_00ba: dup
IL_00bb: stloc.0
IL_00bc: stfld ""int C.<Main>d__0.<>1__state""
IL_00c1: ldarg.0
IL_00c2: ldloca.s V_2
IL_00c4: call ""bool System.Runtime.CompilerServices.TaskAwaiter<bool>.GetResult()""
IL_00c9: stfld ""bool C.<Main>d__0.<>s__3""
IL_00ce: ldarg.0
IL_00cf: ldfld ""bool C.<Main>d__0.<>s__3""
IL_00d4: brtrue IL_0039
IL_00d9: ldarg.0
IL_00da: ldnull
IL_00db: stfld ""C.Enumerator C.<Main>d__0.<>s__1""
IL_00e0: leave.s IL_00fc
}
catch System.Exception
{
// async: catch handler, sequence point: <hidden>
IL_00e2: stloc.s V_4
IL_00e4: ldarg.0
IL_00e5: ldc.i4.s -2
IL_00e7: stfld ""int C.<Main>d__0.<>1__state""
IL_00ec: ldarg.0
IL_00ed: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_00f2: ldloc.s V_4
IL_00f4: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
IL_00f9: nop
IL_00fa: leave.s IL_0110
}
// sequence point: }
IL_00fc: ldarg.0
IL_00fd: ldc.i4.s -2
IL_00ff: stfld ""int C.<Main>d__0.<>1__state""
// sequence point: <hidden>
IL_0104: ldarg.0
IL_0105: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_010a: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
IL_010f: nop
IL_0110: ret
}
", sequencePoints: "C+<Main>d__0.MoveNext", source: source + s_IAsyncEnumerable);
}
[Fact]
public void TestWithPattern_WithIAsyncDisposable()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator : System.IAsyncDisposable
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var memberModel = model.GetMemberModel(foreachSyntax);
BoundForEachStatement boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4)");
}
[Fact]
public void TestWithPattern_WithIAsyncDisposableUseSiteError()
{
string enumerator = @"
using System.Threading.Tasks;
public class C
{
public Enumerator GetAsyncEnumerator() => throw null;
public sealed class Enumerator : System.IAsyncDisposable
{
public int Current { get => throw null; }
public Task<bool> MoveNextAsync() => throw null;
public async ValueTask DisposeAsync()
{
await Task.Yield();
}
}
}";
string source = @"
using System.Threading.Tasks;
class Client
{
async Task M()
{
await foreach (var i in new C())
{
}
}
}";
var lib = CreateCompilationWithTasksExtensions(enumerator + s_IAsyncEnumerable);
lib.VerifyDiagnostics();
var comp = CreateCompilationWithTasksExtensions(source, references: new[] { lib.EmitToImageReference() });
comp.MakeTypeMissing(WellKnownType.System_IAsyncDisposable);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[Fact]
public void TestWithMultipleInterface()
{
string source = @"
using System.Collections.Generic;
class C : IAsyncEnumerable<int>, IAsyncEnumerable<string>
{
async System.Threading.Tasks.Task M()
{
await foreach (var i in new C())
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw null;
}
IAsyncEnumerator<string> IAsyncEnumerable<string>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (7,33): error CS8413: Async foreach statement cannot operate on variables of type 'C' because it implements multiple instantiations of 'IAsyncEnumerable<T>'; try casting to a specific interface instantiation
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_MultipleIAsyncEnumOfT, "new C()").WithArguments("C", "System.Collections.Generic.IAsyncEnumerable<T>").WithLocation(7, 33)
);
}
[Fact]
public void TestWithMultipleImplementations()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class Base : IAsyncEnumerable<string>
{
IAsyncEnumerator<string> IAsyncEnumerable<string>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}
class C : Base, IAsyncEnumerable<int>
{
async Task M()
{
await foreach (var i in new C())
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (13,33): error CS8413: Async foreach statement cannot operate on variables of type 'C' because it implements multiple instantiations of 'IAsyncEnumerable<T>'; try casting to a specific interface instantiation
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_MultipleIAsyncEnumOfT, "new C()").WithArguments("C", "System.Collections.Generic.IAsyncEnumerable<T>").WithLocation(13, 33)
);
}
[Fact]
public void TestWithInterface()
{
string source = @"
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using static System.Console;
class C : IAsyncEnumerable<int>
{
static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<int>
{
int i = 0;
int IAsyncEnumerator<int>.Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
async ValueTask<bool> IAsyncEnumerator<int>.MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
async ValueTask IAsyncDisposable.DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4)");
var tree = comp.SyntaxTrees.First();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<System.Int32> System.Collections.Generic.IAsyncEnumerable<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 System.Collections.Generic.IAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()", info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[Fact]
public void TestWithInterface_OnStruct_ImplicitInterfaceImplementation()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
struct C : IAsyncEnumerable<int>
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
class AsyncEnumerator : IAsyncEnumerator<int>
{
public int i;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
// Note: the enumerator type should not be a struct, otherwise you will loop forever
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
var verifier = CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4)");
// The thing to notice here is that the call to GetAsyncEnumerator is a constrained call (we're not boxing to `IAsyncEnumerable<int>`)
verifier.VerifyIL("C.<Main>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext()", @"
{
// Code size 496 (0x1f0)
.maxstack 3
.locals init (int V_0,
C V_1,
System.Threading.CancellationToken V_2,
System.Runtime.CompilerServices.ValueTaskAwaiter<bool> V_3,
System.Threading.Tasks.ValueTask<bool> V_4,
C.<Main>d__0 V_5,
object V_6,
System.Runtime.CompilerServices.ValueTaskAwaiter V_7,
System.Threading.Tasks.ValueTask V_8,
System.Exception V_9)
IL_0000: ldarg.0
IL_0001: ldfld ""int C.<Main>d__0.<>1__state""
IL_0006: stloc.0
.try
{
IL_0007: ldloc.0
IL_0008: brfalse.s IL_0012
IL_000a: br.s IL_000c
IL_000c: ldloc.0
IL_000d: ldc.i4.1
IL_000e: beq.s IL_0014
IL_0010: br.s IL_0019
IL_0012: br.s IL_004c
IL_0014: br IL_015c
IL_0019: nop
IL_001a: nop
IL_001b: ldarg.0
IL_001c: ldloca.s V_1
IL_001e: dup
IL_001f: initobj ""C""
IL_0025: ldloca.s V_2
IL_0027: initobj ""System.Threading.CancellationToken""
IL_002d: ldloc.2
IL_002e: constrained. ""C""
IL_0034: callvirt ""System.Collections.Generic.IAsyncEnumerator<int> System.Collections.Generic.IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken)""
IL_0039: stfld ""System.Collections.Generic.IAsyncEnumerator<int> C.<Main>d__0.<>s__1""
IL_003e: ldarg.0
IL_003f: ldnull
IL_0040: stfld ""object C.<Main>d__0.<>s__2""
IL_0045: ldarg.0
IL_0046: ldc.i4.0
IL_0047: stfld ""int C.<Main>d__0.<>s__3""
IL_004c: nop
.try
{
IL_004d: ldloc.0
IL_004e: brfalse.s IL_0052
IL_0050: br.s IL_0054
IL_0052: br.s IL_00ca
IL_0054: br.s IL_0084
IL_0056: ldarg.0
IL_0057: ldarg.0
IL_0058: ldfld ""System.Collections.Generic.IAsyncEnumerator<int> C.<Main>d__0.<>s__1""
IL_005d: callvirt ""int System.Collections.Generic.IAsyncEnumerator<int>.Current.get""
IL_0062: stfld ""int C.<Main>d__0.<i>5__4""
IL_0067: nop
IL_0068: ldstr ""Got({0}) ""
IL_006d: ldarg.0
IL_006e: ldfld ""int C.<Main>d__0.<i>5__4""
IL_0073: box ""int""
IL_0078: call ""string string.Format(string, object)""
IL_007d: call ""void System.Console.Write(string)""
IL_0082: nop
IL_0083: nop
IL_0084: ldarg.0
IL_0085: ldfld ""System.Collections.Generic.IAsyncEnumerator<int> C.<Main>d__0.<>s__1""
IL_008a: callvirt ""System.Threading.Tasks.ValueTask<bool> System.Collections.Generic.IAsyncEnumerator<int>.MoveNextAsync()""
IL_008f: stloc.s V_4
IL_0091: ldloca.s V_4
IL_0093: call ""System.Runtime.CompilerServices.ValueTaskAwaiter<bool> System.Threading.Tasks.ValueTask<bool>.GetAwaiter()""
IL_0098: stloc.3
IL_0099: ldloca.s V_3
IL_009b: call ""bool System.Runtime.CompilerServices.ValueTaskAwaiter<bool>.IsCompleted.get""
IL_00a0: brtrue.s IL_00e6
IL_00a2: ldarg.0
IL_00a3: ldc.i4.0
IL_00a4: dup
IL_00a5: stloc.0
IL_00a6: stfld ""int C.<Main>d__0.<>1__state""
IL_00ab: ldarg.0
IL_00ac: ldloc.3
IL_00ad: stfld ""System.Runtime.CompilerServices.ValueTaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00b2: ldarg.0
IL_00b3: stloc.s V_5
IL_00b5: ldarg.0
IL_00b6: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_00bb: ldloca.s V_3
IL_00bd: ldloca.s V_5
IL_00bf: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.ValueTaskAwaiter<bool>, C.<Main>d__0>(ref System.Runtime.CompilerServices.ValueTaskAwaiter<bool>, ref C.<Main>d__0)""
IL_00c4: nop
IL_00c5: leave IL_01ef
IL_00ca: ldarg.0
IL_00cb: ldfld ""System.Runtime.CompilerServices.ValueTaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00d0: stloc.3
IL_00d1: ldarg.0
IL_00d2: ldflda ""System.Runtime.CompilerServices.ValueTaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00d7: initobj ""System.Runtime.CompilerServices.ValueTaskAwaiter<bool>""
IL_00dd: ldarg.0
IL_00de: ldc.i4.m1
IL_00df: dup
IL_00e0: stloc.0
IL_00e1: stfld ""int C.<Main>d__0.<>1__state""
IL_00e6: ldarg.0
IL_00e7: ldloca.s V_3
IL_00e9: call ""bool System.Runtime.CompilerServices.ValueTaskAwaiter<bool>.GetResult()""
IL_00ee: stfld ""bool C.<Main>d__0.<>s__5""
IL_00f3: ldarg.0
IL_00f4: ldfld ""bool C.<Main>d__0.<>s__5""
IL_00f9: brtrue IL_0056
IL_00fe: leave.s IL_010c
}
catch object
{
IL_0100: stloc.s V_6
IL_0102: ldarg.0
IL_0103: ldloc.s V_6
IL_0105: stfld ""object C.<Main>d__0.<>s__2""
IL_010a: leave.s IL_010c
}
IL_010c: ldarg.0
IL_010d: ldfld ""System.Collections.Generic.IAsyncEnumerator<int> C.<Main>d__0.<>s__1""
IL_0112: brfalse.s IL_0181
IL_0114: ldarg.0
IL_0115: ldfld ""System.Collections.Generic.IAsyncEnumerator<int> C.<Main>d__0.<>s__1""
IL_011a: callvirt ""System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()""
IL_011f: stloc.s V_8
IL_0121: ldloca.s V_8
IL_0123: call ""System.Runtime.CompilerServices.ValueTaskAwaiter System.Threading.Tasks.ValueTask.GetAwaiter()""
IL_0128: stloc.s V_7
IL_012a: ldloca.s V_7
IL_012c: call ""bool System.Runtime.CompilerServices.ValueTaskAwaiter.IsCompleted.get""
IL_0131: brtrue.s IL_0179
IL_0133: ldarg.0
IL_0134: ldc.i4.1
IL_0135: dup
IL_0136: stloc.0
IL_0137: stfld ""int C.<Main>d__0.<>1__state""
IL_013c: ldarg.0
IL_013d: ldloc.s V_7
IL_013f: stfld ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<Main>d__0.<>u__2""
IL_0144: ldarg.0
IL_0145: stloc.s V_5
IL_0147: ldarg.0
IL_0148: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_014d: ldloca.s V_7
IL_014f: ldloca.s V_5
IL_0151: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.ValueTaskAwaiter, C.<Main>d__0>(ref System.Runtime.CompilerServices.ValueTaskAwaiter, ref C.<Main>d__0)""
IL_0156: nop
IL_0157: leave IL_01ef
IL_015c: ldarg.0
IL_015d: ldfld ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<Main>d__0.<>u__2""
IL_0162: stloc.s V_7
IL_0164: ldarg.0
IL_0165: ldflda ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<Main>d__0.<>u__2""
IL_016a: initobj ""System.Runtime.CompilerServices.ValueTaskAwaiter""
IL_0170: ldarg.0
IL_0171: ldc.i4.m1
IL_0172: dup
IL_0173: stloc.0
IL_0174: stfld ""int C.<Main>d__0.<>1__state""
IL_0179: ldloca.s V_7
IL_017b: call ""void System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()""
IL_0180: nop
IL_0181: ldarg.0
IL_0182: ldfld ""object C.<Main>d__0.<>s__2""
IL_0187: stloc.s V_6
IL_0189: ldloc.s V_6
IL_018b: brfalse.s IL_01aa
IL_018d: ldloc.s V_6
IL_018f: isinst ""System.Exception""
IL_0194: stloc.s V_9
IL_0196: ldloc.s V_9
IL_0198: brtrue.s IL_019d
IL_019a: ldloc.s V_6
IL_019c: throw
IL_019d: ldloc.s V_9
IL_019f: call ""System.Runtime.ExceptionServices.ExceptionDispatchInfo System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(System.Exception)""
IL_01a4: callvirt ""void System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()""
IL_01a9: nop
IL_01aa: ldarg.0
IL_01ab: ldfld ""int C.<Main>d__0.<>s__3""
IL_01b0: pop
IL_01b1: ldarg.0
IL_01b2: ldnull
IL_01b3: stfld ""object C.<Main>d__0.<>s__2""
IL_01b8: ldarg.0
IL_01b9: ldnull
IL_01ba: stfld ""System.Collections.Generic.IAsyncEnumerator<int> C.<Main>d__0.<>s__1""
IL_01bf: leave.s IL_01db
}
catch System.Exception
{
IL_01c1: stloc.s V_9
IL_01c3: ldarg.0
IL_01c4: ldc.i4.s -2
IL_01c6: stfld ""int C.<Main>d__0.<>1__state""
IL_01cb: ldarg.0
IL_01cc: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_01d1: ldloc.s V_9
IL_01d3: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
IL_01d8: nop
IL_01d9: leave.s IL_01ef
}
IL_01db: ldarg.0
IL_01dc: ldc.i4.s -2
IL_01de: stfld ""int C.<Main>d__0.<>1__state""
IL_01e3: ldarg.0
IL_01e4: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_01e9: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
IL_01ee: nop
IL_01ef: ret
}");
}
[Fact]
public void TestWithInterface_WithEarlyCompletion1()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
Write($""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator(2);
}
internal sealed class AsyncEnumerator : IAsyncEnumerator<int>
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
return new ValueTask(Task.CompletedTask); // return a completed task
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4) Done");
}
[Fact]
public void TestWithInterface_WithBreakAndContinue()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
if (i == 2 || i == 3) { Write($""Continue({i}) ""); continue; }
if (i == 4) { Write(""Break ""); break; }
Write($""Got({i}) "");
}
Write(""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<int>
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 10);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Continue(2) NextAsync(2) Current(3) Continue(3) NextAsync(3) Current(4) Break Dispose(4) Done");
}
[Fact]
public void TestWithInterface_WithGoto()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
if (i == 2 || i == 3) { Write($""Continue({i}) ""); continue; }
if (i == 4) { Write(""Goto ""); goto done; }
Write($""Got({i}) "");
}
done:
Write(""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<int>
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 10);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Continue(2) NextAsync(2) Current(3) Continue(3) NextAsync(3) Current(4) Goto Dispose(4) Done");
}
[Fact]
public void TestWithInterface_WithStruct()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
static async Task Main()
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
Write($""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator(0);
}
internal struct AsyncEnumerator : IAsyncEnumerator<int>
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
i++;
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
bool more = await Task.FromResult(i < 4);
i = i + 100; // Note: side-effects of async methods in structs are lost
return more;
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp,
expectedOutput: "NextAsync(0) Current(0) Got(1) NextAsync(1) Current(1) Got(2) NextAsync(2) Current(2) Got(3) NextAsync(3) Current(3) Got(4) NextAsync(4) Dispose(4) Done");
}
[Fact, WorkItem(27651, "https://github.com/dotnet/roslyn/issues/27651")]
public void TestControlFlowAnalysis()
{
string source = @"
class C
{
async System.Threading.Tasks.Task M(System.Collections.Generic.IAsyncEnumerable<int> collection)
{
await foreach (var item in collection) { }
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics();
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
var loop = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var ctrlFlowAnalysis = model.AnalyzeControlFlow(loop);
Assert.Equal(0, ctrlFlowAnalysis.ExitPoints.Count());
}
[Fact]
public void TestWithNullLiteralCollection()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
async Task M()
{
await foreach (var i in null)
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (8,33): error CS0186: Use of null is not valid in this context
// await foreach (var i in null)
Diagnostic(ErrorCode.ERR_NullNotValid, "null").WithLocation(8, 33)
);
}
[Fact]
public void TestWithNullCollection()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task Main()
{
C c = null;
try
{
await foreach (var i in c)
{
}
}
catch (System.NullReferenceException)
{
System.Console.Write(""Success"");
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator(0);
}
internal struct AsyncEnumerator : IAsyncEnumerator<int>
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current { get => throw new System.Exception(); }
public ValueTask<bool> MoveNextAsync() => throw new System.Exception();
public ValueTask DisposeAsync() => throw new System.Exception();
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "Success");
}
[Fact]
public void TestInCatch()
{
string source = @"
using System.Collections.Generic;
using static System.Console;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task Main()
{
try
{
Write($""Try "");
throw null;
}
catch (System.NullReferenceException)
{
await foreach (var i in new C())
{
Write($""Got({i}) "");
}
}
Write($""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator(0);
}
internal class AsyncEnumerator : IAsyncEnumerator<int>
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "Try NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Current(3) Got(3) NextAsync(3) Dispose(4) Done");
}
/// Covered in greater details by <see cref="CodeGenAsyncIteratorTests.TryFinally_AwaitForeachInFinally"/>
[Fact]
public void TestInFinally()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task Main()
{
try
{
}
finally
{
await foreach (var i in new C())
{
}
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics();
}
[Fact]
public void TestWithConversionToElement()
{
string source = @"
using System.Collections.Generic;
using static System.Console;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task Main()
{
await foreach (Element i in new C())
{
Write($""Got({i}) "");
}
Write($""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator(0);
}
internal class AsyncEnumerator : IAsyncEnumerator<int>
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}
class Element
{
int i;
public static implicit operator Element(int value) { Write($""Convert({value}) ""); return new Element(value); }
private Element(int value) { i = value; }
public override string ToString() => i.ToString();
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Convert(1) Got(1) NextAsync(1) Current(2) Convert(2) Got(2) NextAsync(2) Dispose(3) Done");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<System.Int32> System.Collections.Generic.IAsyncEnumerable<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 System.Collections.Generic.IAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()", info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.ExplicitUserDefined, info.ElementConversion.Kind);
Assert.Equal("Element Element.op_Implicit(System.Int32 value)", info.ElementConversion.MethodSymbol.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[Fact]
public void TestWithNullableCollection()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
struct C : IAsyncEnumerable<int>
{
static async System.Threading.Tasks.Task Main()
{
C? c = new C(); // non-null value
await foreach (var i in c)
{
Write($""Got({i}) "");
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<int>
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1) NextAsync(1) Current(2) Got(2) NextAsync(2) Dispose(3)");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<System.Int32> System.Collections.Generic.IAsyncEnumerable<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 System.Collections.Generic.IAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()", info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[Fact]
public void TestWithNullableCollection2()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
struct C : IAsyncEnumerable<int>
{
static async Task Main()
{
C? c = null; // null value
try
{
await foreach (var i in c)
{
Write($""UNREACHABLE"");
}
}
catch (System.InvalidOperationException)
{
Write($""Success"");
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw new System.Exception();
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "Success");
}
[Fact]
public void TestWithInterfaceAndDeconstruction()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var (i, j) in new C())
{
Write($""Got({i},{j}) "");
}
Write($""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<int>
{
int i = 0;
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}
public static class Extensions
{
public static void Deconstruct(this int i, out string x1, out int x2) { Write($""Deconstruct({i}) ""); x1 = i.ToString(); x2 = -i; }
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Deconstruct(1) Got(1,-1) NextAsync(1) Current(2) Deconstruct(2) Got(2,-2) NextAsync(2) Dispose(3) Done");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachVariableStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<System.Int32> System.Collections.Generic.IAsyncEnumerable<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 System.Collections.Generic.IAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()", info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[Fact]
public void TestWithDeconstructionInNonAsyncMethod()
{
string source = @"
using System.Collections.Generic;
class C : IAsyncEnumerable<int>
{
static void Main()
{
await foreach (var (i, j) in new C())
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
=> throw null;
}
public static class Extensions
{
public static void Deconstruct(this int i, out int x1, out int x2) { x1 = i; x2 = -i; }
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (7,9): 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'.
// await foreach (var (i, j) in new C())
Diagnostic(ErrorCode.ERR_BadAwaitWithoutVoidAsyncMethod, "await").WithLocation(7, 9)
);
}
[Fact]
public void TestWithPatternAndDeconstructionOfTuple()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<(string, int)>
{
public static async System.Threading.Tasks.Task Main()
{
await foreach (var (i, j) in new C())
{
Write($""Got({i},{j}) "");
}
Write($""Done"");
}
IAsyncEnumerator<(string, int)> IAsyncEnumerable<(string, int)>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<(string, int)>
{
int i = 0;
public (string, int) Current
{
get
{
Write($""Current({i}) "");
return (i.ToString(), -i);
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1,-1) NextAsync(1) Current(2) Got(2,-2) NextAsync(2) Dispose(3) Done");
var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachVariableStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<(System.String, System.Int32)> System.Collections.Generic.IAsyncEnumerable<(System.String, System.Int32)>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<(System.String, System.Int32)>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("(System.String, System.Int32) System.Collections.Generic.IAsyncEnumerator<(System.String, System.Int32)>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()", info.DisposeMethod.ToTestDisplayString());
Assert.Equal("(System.String, System.Int32)", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
}
[Fact]
public void TestWithInterfaceAndDeconstruction_ManualIteration()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
static async Task Main()
{
var e = ((IAsyncEnumerable<int>)new C()).GetAsyncEnumerator();
try
{
while (await e.MoveNextAsync())
{
(int i, int j) = e.Current;
Write($""Got({i},{j}) "");
}
}
finally { await e.DisposeAsync(); }
Write($""Done"");
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator(0);
}
internal class AsyncEnumerator : IAsyncEnumerator<int>
{
int i;
internal AsyncEnumerator(int start) { i = start; }
public int Current
{
get
{
Write($""Current({i}) "");
return i;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 3);
}
public async ValueTask DisposeAsync()
{
Write($""Disp"");
await Task.Yield();
Write($""ose({i}) "");
}
}
}
public static class Extensions
{
public static void Deconstruct(this int i, out int x1, out int x2) { x1 = i; x2 = -i; }
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got(1,-1) NextAsync(1) Current(2) Got(2,-2) NextAsync(2) Dispose(3) Done");
}
[Fact]
public void TestWithPatternAndObsolete()
{
string source = @"
using System.Threading.Tasks;
class C
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new C())
{
}
}
[System.Obsolete]
public AsyncEnumerator GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
[System.Obsolete]
public sealed class AsyncEnumerator : System.IAsyncDisposable
{
[System.Obsolete]
public int Current { get => throw null; }
[System.Obsolete]
public Task<bool> MoveNextAsync() => throw null;
[System.Obsolete]
public ValueTask DisposeAsync() => throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics(
// (7,15): warning CS0612: 'C.GetAsyncEnumerator(CancellationToken)' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.GetAsyncEnumerator(System.Threading.CancellationToken)").WithLocation(7, 15),
// (7,15): warning CS0612: 'C.AsyncEnumerator.MoveNextAsync()' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.AsyncEnumerator.MoveNextAsync()").WithLocation(7, 15),
// (7,15): warning CS0612: 'C.AsyncEnumerator.Current' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.AsyncEnumerator.Current").WithLocation(7, 15)
);
// Note: Obsolete on DisposeAsync is not reported since always called through IAsyncDisposable interface
}
[Fact]
public void TestWithUnassignedCollection()
{
string source = @"
using System.Collections.Generic;
class C
{
async System.Threading.Tasks.Task M()
{
C c;
await foreach (var i in c)
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token = default) => throw null;
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (8,33): error CS0165: Use of unassigned local variable 'c'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_UseDefViolation, "c").WithArguments("c").WithLocation(8, 33)
);
}
[Fact]
public void TestInRegularForeach()
{
string source = @"
using System.Collections.Generic;
class C
{
void M()
{
foreach (var i in new C())
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable);
comp.VerifyDiagnostics(
// (7,27): error CS8414: foreach statement cannot operate on variables of type 'C' because 'C' does not contain a public instance or extension definition for 'GetEnumerator'. Did you mean 'await foreach'?
// foreach (var i in new C())
Diagnostic(ErrorCode.ERR_ForEachMissingMemberWrongAsync, "new C()").WithArguments("C", "GetEnumerator").WithLocation(7, 27)
);
}
[Fact]
public void TestWithGenericCollection()
{
string source = @"
using static System.Console;
using System.Collections.Generic;
using System.Threading.Tasks;
class Collection<T> : IAsyncEnumerable<T>
{
IAsyncEnumerator<T> IAsyncEnumerable<T>.GetAsyncEnumerator(System.Threading.CancellationToken token)
{
return new AsyncEnumerator();
}
sealed class AsyncEnumerator : IAsyncEnumerator<T>
{
int i = 0;
public T Current
{
get
{
Write($""Current({i}) "");
return default;
}
}
public async ValueTask<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public async ValueTask DisposeAsync()
{
Write($""Dispose({i}) "");
await Task.Yield();
}
}
}
class C
{
static async System.Threading.Tasks.Task Main()
{
await foreach (var i in new Collection<int>())
{
Write($""Got "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got NextAsync(1) Current(2) Got NextAsync(2) Current(3) Got NextAsync(3) Dispose(4)");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<System.Int32> System.Collections.Generic.IAsyncEnumerable<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 System.Collections.Generic.IAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()", info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.True(internalInfo.NeedsDisposal);
}
[ConditionalFact(typeof(WindowsDesktopOnly), Reason = ConditionalSkipReason.NativePdbRequiresDesktop)]
public void TestWithInterfaceImplementingPattern()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public interface ICollection<T>
{
IMyAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IMyAsyncEnumerator<T>
{
T Current { get; }
Task<bool> MoveNextAsync();
}
public class Collection<T> : ICollection<T>
{
public IMyAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new MyAsyncEnumerator<T>();
}
}
public sealed class MyAsyncEnumerator<T> : IMyAsyncEnumerator<T>
{
int i = 0;
public T Current
{
get
{
Write($""Current({i}) "");
return default;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
}
class C
{
static async System.Threading.Tasks.Task Main()
{
ICollection<int> c = new Collection<int>();
await foreach (var i in c)
{
Write($""Got "");
}
}
}";
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
var verifier = CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got NextAsync(1) Current(2) Got NextAsync(2) Current(3) Got NextAsync(3)");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("IMyAsyncEnumerator<System.Int32> ICollection<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.Task<System.Boolean> IMyAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 IMyAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Null(info.DisposeMethod);
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
var memberModel = model.GetMemberModel(foreachSyntax);
var boundNode = (BoundForEachStatement)memberModel.GetUpperBoundNode(foreachSyntax);
ForEachEnumeratorInfo internalInfo = boundNode.EnumeratorInfoOpt;
Assert.False(internalInfo.NeedsDisposal);
verifier.VerifyIL("C.<Main>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext()", @"
{
// Code size 283 (0x11b)
.maxstack 3
.locals init (int V_0,
System.Threading.CancellationToken V_1,
System.Runtime.CompilerServices.TaskAwaiter<bool> V_2,
C.<Main>d__0 V_3,
System.Exception V_4)
// sequence point: <hidden>
IL_0000: ldarg.0
IL_0001: ldfld ""int C.<Main>d__0.<>1__state""
IL_0006: stloc.0
.try
{
// sequence point: <hidden>
IL_0007: ldloc.0
IL_0008: brfalse.s IL_0012
IL_000a: br.s IL_000c
IL_000c: ldloc.0
IL_000d: ldc.i4.1
IL_000e: beq.s IL_0017
IL_0010: br.s IL_001c
IL_0012: br IL_00a1
IL_0017: br IL_00a1
// sequence point: {
IL_001c: nop
// sequence point: ICollection<int> c = new Collection<int>();
IL_001d: ldarg.0
IL_001e: newobj ""Collection<int>..ctor()""
IL_0023: stfld ""ICollection<int> C.<Main>d__0.<c>5__1""
// sequence point: await foreach
IL_0028: nop
// sequence point: c
IL_0029: ldarg.0
IL_002a: ldarg.0
IL_002b: ldfld ""ICollection<int> C.<Main>d__0.<c>5__1""
IL_0030: ldloca.s V_1
IL_0032: initobj ""System.Threading.CancellationToken""
IL_0038: ldloc.1
IL_0039: callvirt ""IMyAsyncEnumerator<int> ICollection<int>.GetAsyncEnumerator(System.Threading.CancellationToken)""
IL_003e: stfld ""IMyAsyncEnumerator<int> C.<Main>d__0.<>s__2""
// sequence point: <hidden>
IL_0043: br.s IL_0063
// sequence point: var i
IL_0045: ldarg.0
IL_0046: ldarg.0
IL_0047: ldfld ""IMyAsyncEnumerator<int> C.<Main>d__0.<>s__2""
IL_004c: callvirt ""int IMyAsyncEnumerator<int>.Current.get""
IL_0051: stfld ""int C.<Main>d__0.<i>5__3""
// sequence point: {
IL_0056: nop
// sequence point: Write($""Got "");
IL_0057: ldstr ""Got ""
IL_005c: call ""void System.Console.Write(string)""
IL_0061: nop
// sequence point: }
IL_0062: nop
// sequence point: in
IL_0063: ldarg.0
IL_0064: ldfld ""IMyAsyncEnumerator<int> C.<Main>d__0.<>s__2""
IL_0069: callvirt ""System.Threading.Tasks.Task<bool> IMyAsyncEnumerator<int>.MoveNextAsync()""
IL_006e: callvirt ""System.Runtime.CompilerServices.TaskAwaiter<bool> System.Threading.Tasks.Task<bool>.GetAwaiter()""
IL_0073: stloc.2
// sequence point: <hidden>
IL_0074: ldloca.s V_2
IL_0076: call ""bool System.Runtime.CompilerServices.TaskAwaiter<bool>.IsCompleted.get""
IL_007b: brtrue.s IL_00bd
IL_007d: ldarg.0
IL_007e: ldc.i4.0
IL_007f: dup
IL_0080: stloc.0
IL_0081: stfld ""int C.<Main>d__0.<>1__state""
// async: yield
IL_0086: ldarg.0
IL_0087: ldloc.2
IL_0088: stfld ""System.Runtime.CompilerServices.TaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_008d: ldarg.0
IL_008e: stloc.3
IL_008f: ldarg.0
IL_0090: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_0095: ldloca.s V_2
IL_0097: ldloca.s V_3
IL_0099: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<bool>, C.<Main>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<bool>, ref C.<Main>d__0)""
IL_009e: nop
IL_009f: leave.s IL_011a
// async: resume
IL_00a1: ldarg.0
IL_00a2: ldfld ""System.Runtime.CompilerServices.TaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00a7: stloc.2
IL_00a8: ldarg.0
IL_00a9: ldflda ""System.Runtime.CompilerServices.TaskAwaiter<bool> C.<Main>d__0.<>u__1""
IL_00ae: initobj ""System.Runtime.CompilerServices.TaskAwaiter<bool>""
IL_00b4: ldarg.0
IL_00b5: ldc.i4.m1
IL_00b6: dup
IL_00b7: stloc.0
IL_00b8: stfld ""int C.<Main>d__0.<>1__state""
IL_00bd: ldarg.0
IL_00be: ldloca.s V_2
IL_00c0: call ""bool System.Runtime.CompilerServices.TaskAwaiter<bool>.GetResult()""
IL_00c5: stfld ""bool C.<Main>d__0.<>s__4""
IL_00ca: ldarg.0
IL_00cb: ldfld ""bool C.<Main>d__0.<>s__4""
IL_00d0: brtrue IL_0045
IL_00d5: ldarg.0
IL_00d6: ldnull
IL_00d7: stfld ""IMyAsyncEnumerator<int> C.<Main>d__0.<>s__2""
IL_00dc: leave.s IL_00ff
}
catch System.Exception
{
// async: catch handler, sequence point: <hidden>
IL_00de: stloc.s V_4
IL_00e0: ldarg.0
IL_00e1: ldc.i4.s -2
IL_00e3: stfld ""int C.<Main>d__0.<>1__state""
IL_00e8: ldarg.0
IL_00e9: ldnull
IL_00ea: stfld ""ICollection<int> C.<Main>d__0.<c>5__1""
IL_00ef: ldarg.0
IL_00f0: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_00f5: ldloc.s V_4
IL_00f7: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
IL_00fc: nop
IL_00fd: leave.s IL_011a
}
// sequence point: }
IL_00ff: ldarg.0
IL_0100: ldc.i4.s -2
IL_0102: stfld ""int C.<Main>d__0.<>1__state""
// sequence point: <hidden>
IL_0107: ldarg.0
IL_0108: ldnull
IL_0109: stfld ""ICollection<int> C.<Main>d__0.<c>5__1""
IL_010e: ldarg.0
IL_010f: ldflda ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<Main>d__0.<>t__builder""
IL_0114: call ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
IL_0119: nop
IL_011a: ret
}", sequencePoints: "C+<Main>d__0.MoveNext", source: source);
}
[ConditionalFact(typeof(WindowsDesktopOnly), Reason = ConditionalSkipReason.NativePdbRequiresDesktop)]
public void TestWithInterfaceImplementingPattern_ChildImplementsDisposeAsync()
{
string source = @"
using static System.Console;
using System.Threading.Tasks;
public interface ICollection<T>
{
IMyAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default);
}
public interface IMyAsyncEnumerator<T>
{
T Current { get; }
Task<bool> MoveNextAsync();
}
public class Collection<T> : ICollection<T>
{
public IMyAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token = default)
{
return new MyAsyncEnumerator<T>();
}
}
public sealed class MyAsyncEnumerator<T> : IMyAsyncEnumerator<T>
{
int i = 0;
public T Current
{
get
{
Write($""Current({i}) "");
return default;
}
}
public async Task<bool> MoveNextAsync()
{
Write($""NextAsync({i}) "");
i++;
return await Task.FromResult(i < 4);
}
public System.Threading.Tasks.ValueTask DisposeAsync()
=> throw null;
}
class C
{
static async System.Threading.Tasks.Task Main()
{
ICollection<int> c = new Collection<int>();
await foreach (var i in c)
{
Write($""Got "");
}
}
}";
// DisposeAsync on implementing type is ignored, since we don't do runtime check
var comp = CreateCompilationWithTasksExtensions(source + s_IAsyncEnumerable, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
var verifier = CompileAndVerify(comp, expectedOutput: "NextAsync(0) Current(1) Got NextAsync(1) Current(2) Got NextAsync(2) Current(3) Got NextAsync(3)");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Null(info.DisposeMethod);
}
[Fact]
public void GetAsyncEnumerator_CancellationTokenMustBeOptional()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token)
{
throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
[WorkItem(50182, "https://github.com/dotnet/roslyn/issues/50182")]
public void GetAsyncEnumerator_CancellationTokenMustBeOptional_OnIAsyncEnumerable()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C
{
public static async Task M(IAsyncEnumerable<int> e)
{
await foreach (var i in e)
{
}
}
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token);
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
System.Threading.Tasks.ValueTask<bool> MoveNextAsync();
T Current { get; }
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'IAsyncEnumerable<int>' because 'IAsyncEnumerable<int>' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in e)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "e").WithArguments("System.Collections.Generic.IAsyncEnumerable<int>", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
[WorkItem(50182, "https://github.com/dotnet/roslyn/issues/50182")]
public void GetAsyncEnumerator_CancellationTokenMustBeOptional_OnIAsyncEnumerable_ImplicitImplementation()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task M(C c)
{
await foreach (var i in c)
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(System.Threading.CancellationToken token) => throw null;
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token);
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
System.Threading.Tasks.ValueTask<bool> MoveNextAsync();
T Current { get; }
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "c").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
[WorkItem(50182, "https://github.com/dotnet/roslyn/issues/50182")]
public void GetAsyncEnumerator_CancellationTokenMustBeOptional_OnIAsyncEnumerable_ExplicitImplementation()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task M(C c)
{
await foreach (var i in c)
{
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken token) => throw null;
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(System.Threading.CancellationToken token);
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
System.Threading.Tasks.ValueTask<bool> MoveNextAsync();
T Current { get; }
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "c").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void GetAsyncEnumerator_Missing()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C : IAsyncEnumerable<int>
{
public static async Task M(C c)
{
await foreach (var i in c)
{
}
}
}
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
}
public interface IAsyncEnumerator<out T> : System.IAsyncDisposable
{
System.Threading.Tasks.ValueTask<bool> MoveNextAsync();
T Current { get; }
}
}
namespace System
{
public interface IAsyncDisposable
{
System.Threading.Tasks.ValueTask DisposeAsync();
}
}
";
var comp = CreateCompilationWithTasksExtensions(source);
comp.VerifyEmitDiagnostics(
// (8,33): error CS0656: Missing compiler required member 'System.Collections.Generic.IAsyncEnumerable`1.GetAsyncEnumerator'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "c").WithArguments("System.Collections.Generic.IAsyncEnumerable`1", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void GetAsyncEnumerator_WithOptionalParameter()
{
string source = @"
using System.Collections.Generic;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator(int opt = 0)
{
throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics();
}
[Fact]
public void GetAsyncEnumerator_WithParams()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator(params int[] x)
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync"");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync");
}
[Fact]
public void GetAsyncEnumerator_WithMultipleValidCandidatesWithOptionalParameters()
{
string source = @"
using System.Threading.Tasks;
using System.Collections.Generic;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public IEnumerator<int> GetAsyncEnumerator(int a = 0) => throw null;
public IEnumerator<int> GetAsyncEnumerator(bool a = true) => throw null;
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (8,33): warning CS0278: 'C' does not implement the 'collection' pattern. 'C.GetAsyncEnumerator(int)' is ambiguous with 'C.GetAsyncEnumerator(bool)'.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternIsAmbiguous, "new C()").WithArguments("C", "collection", "C.GetAsyncEnumerator(int)", "C.GetAsyncEnumerator(bool)").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void GetAsyncEnumerator_WithMultipleInvalidCandidates()
{
string source = @"
using System.Threading.Tasks;
using System.Collections.Generic;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public IEnumerator<int> GetAsyncEnumerator(int a) => throw null;
public IEnumerator<int> GetAsyncEnumerator(bool a) => throw null;
}";
var comp = CreateCompilationWithMscorlib46(source);
comp.VerifyDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public async Task DisposeAsync()
{
System.Console.Write(""DisposeAsync "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_TwoOverloads()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public async Task DisposeAsync(int i = 0)
{
System.Console.Write(""DisposeAsync "");
await Task.Yield();
}
public Task DisposeAsync(params string[] s)
=> throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_NoExtensions()
{
string source = @"
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
}
}
public static class Extension
{
public static ValueTask DisposeAsync(this C.Enumerator e) => throw null;
}";
// extension methods do not contribute to pattern-based disposal
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_NoExtensions_TwoExtensions()
{
string source = @"
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
}
}
public static class Extension1
{
public static ValueTask DisposeAsync(this C.Enumerator c) => throw null;
}
public static class Extension2
{
public static ValueTask DisposeAsync(this C.Enumerator c) => throw null;
}
";
// extension methods do not contribute to pattern-based disposal
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_InstanceMethodPreferredOverInterface()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator : System.IAsyncDisposable
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
ValueTask System.IAsyncDisposable.DisposeAsync() => throw null;
public async ValueTask DisposeAsync()
{
System.Console.Write(""DisposeAsync "");
await Task.Yield();
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_ReturnsVoid()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator()
=> throw null;
public sealed class Enumerator
{
public Task<bool> MoveNextAsync()
=> throw null;
public int Current
{
get => throw null;
}
public void DisposeAsync()
=> throw null;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (7,33): error CS4008: Cannot await 'void'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadAwaitArgVoidCall, "new C()").WithLocation(7, 33)
);
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_ReturnsInt()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public int DisposeAsync()
{
throw null;
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable });
comp.VerifyDiagnostics(
// (7,33): error CS1061: 'int' does not contain a definition for 'GetAwaiter' and no accessible extension method 'GetAwaiter' accepting a first argument of type 'int' could be found (are you missing a using directive or an assembly reference?)
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMemberOrExtension, "new C()").WithArguments("int", "GetAwaiter").WithLocation(7, 33)
);
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_ReturnsAwaitable()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public Awaitable DisposeAsync()
{
System.Console.Write(""DisposeAsync "");
return new Awaitable();
}
}
}
public class Awaitable
{
public Awaiter GetAwaiter() { return new Awaiter(); }
}
public class Awaiter : System.Runtime.CompilerServices.INotifyCompletion
{
public bool IsCompleted { get { return true; } }
public bool GetResult() { return true; }
public void OnCompleted(System.Action continuation) { }
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_ReturnsTask()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public async Task DisposeAsync()
{
System.Console.Write(""DisposeAsync "");
await Task.Yield();
}
}
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync Done");
}
[Fact]
[WorkItem(32316, "https://github.com/dotnet/roslyn/issues/32316")]
public void PatternBasedDisposal_ReturnsTaskOfInt()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public async Task<int> DisposeAsync()
{
System.Console.Write(""DisposeAsync "");
await Task.Yield();
return 1;
}
}
}
";
// it's okay to await `Task<int>` even if we don't care about the result
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync Done");
}
[Fact]
public void PatternBasedDisposal_WithOptionalParameter()
{
string source = @"
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
}
System.Console.Write(""Done"");
}
public Enumerator GetAsyncEnumerator()
{
return new Enumerator();
}
public sealed class Enumerator
{
public async Task<bool> MoveNextAsync()
{
System.Console.Write(""MoveNextAsync "");
await Task.Yield();
return false;
}
public int Current
{
get => throw null;
}
public async Task<int> DisposeAsync(int i = 1)
{
System.Console.Write($""DisposeAsync {i} "");
await Task.Yield();
return 1;
}
}
}
";
// it's okay to await `Task<int>` even if we don't care about the result
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "MoveNextAsync DisposeAsync 1 Done");
}
[Fact]
[WorkItem(30956, "https://github.com/dotnet/roslyn/issues/30956")]
public void GetAwaiterBoxingConversion()
{
var source =
@"using System;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
interface I1 { }
interface I2 { }
struct StructAwaitable1 : I1 { }
struct StructAwaitable2 : I2 { }
class Enumerable
{
public Enumerator GetAsyncEnumerator() => new Enumerator();
internal class Enumerator
{
public object Current => null;
public StructAwaitable1 MoveNextAsync() => new StructAwaitable1();
public StructAwaitable2 DisposeAsync() => new StructAwaitable2();
}
}
static class Extensions
{
internal static TaskAwaiter<bool> GetAwaiter(this I1 x)
{
if (x == null) throw new ArgumentNullException(nameof(x));
Console.Write(x);
return Task.FromResult(false).GetAwaiter();
}
internal static TaskAwaiter GetAwaiter(this I2 x)
{
if (x == null) throw new ArgumentNullException(nameof(x));
Console.Write(x);
return Task.CompletedTask.GetAwaiter();
}
}
class Program
{
static async Task Main()
{
await foreach (var o in new Enumerable())
{
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.ReleaseExe);
CompileAndVerify(comp, expectedOutput: "StructAwaitable1StructAwaitable2");
}
[Fact]
public void TestInvalidForeachOnConstantNullObject()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in (object)null)
{
Console.Write(i);
}
}
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'object' because 'object' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in (object)null)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "(object)null").WithArguments("object", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestConstantNullObjectImplementingIEnumerable()
{
var source = @"
using System;
using System.Threading.Tasks;
using System.Collections.Generic;
public class C
{
public static async Task Main()
{
await foreach (var i in (IAsyncEnumerable<int>)null)
{
Console.Write(i);
}
}
}";
CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (9,33): error CS0186: Use of null is not valid in this context
// await foreach (var i in (IAsyncEnumerable<int>)null)
Diagnostic(ErrorCode.ERR_NullNotValid, "(IAsyncEnumerable<int>)null").WithLocation(9, 33)
);
}
[Fact]
public void TestConstantNullObjectWithGetAsyncEnumeratorPattern()
{
var source = @"
using System;
using System.Threading.Tasks;
using System.Collections.Generic;
public class C
{
public static async Task Main()
{
await foreach (var i in (C)null)
{
Console.Write(i);
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator() => throw null;
}";
CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (9,33): error CS0186: Use of null is not valid in this context
// await foreach (var i in (C)null)
Diagnostic(ErrorCode.ERR_NullNotValid, "(C)null").WithLocation(9, 33)
);
}
[Fact]
public void TestConstantNullableImplementingIEnumerable()
{
var source = @"
using System;
using System.Threading.Tasks;
using System.Collections.Generic;
public struct C : IAsyncEnumerable<int>
{
public static async Task Main()
{
await foreach (var i in (C?)null)
{
Console.Write(i);
}
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.CancellationToken cancellationToken) => throw null;
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp);
}
[Fact]
public void TestConstantNullableWithGetAsyncEnumeratorPattern()
{
var source = @"
using System;
using System.Threading.Tasks;
using System.Collections.Generic;
public struct C
{
public static async Task Main()
{
await foreach (var i in (C?)null)
{
Console.Write(i);
}
}
public IAsyncEnumerator<int> GetAsyncEnumerator() => throw null;
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp);
}
[Fact]
public void TestForeachNullLiteral()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in null)
{
Console.Write(i);
}
}
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS0186: Use of null is not valid in this context
// await foreach (var i in null)
Diagnostic(ErrorCode.ERR_NullNotValid, "null").WithLocation(8, 33)
);
}
[Fact]
public void TestForeachDefaultLiteral()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in default)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS8716: There is no target type for the default literal.
// await foreach (var i in default)
Diagnostic(ErrorCode.ERR_DefaultLiteralNoTargetType, "default").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensions()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
var tree = comp.SyntaxTrees.Single();
var model = (SyntaxTreeSemanticModel)comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("C.Enumerator Extensions.GetAsyncEnumerator(this C self)", info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.Task<System.Boolean> C.Enumerator.MoveNextAsync()", info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 C.Enumerator.Current { get; private set; }", info.CurrentProperty.ToTestDisplayString());
Assert.Null(info.DisposeMethod);
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
Assert.Equal(ConversionKind.Identity, info.ElementConversion.Kind);
Assert.Equal(ConversionKind.Identity, info.CurrentConversion.Kind);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithUpcast()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnDefaultObject()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in default(object))
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithStructEnumerator()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithUserDefinedImplicitConversion()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static implicit operator int(C c) => 0;
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this int self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (10,33): error CS1929: 'C' does not contain a definition for 'GetAsyncEnumerator' and the best extension method overload 'Extensions.GetAsyncEnumerator(int)' requires a receiver of type 'int'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadInstanceArgType, "new C()").WithArguments("C", "GetAsyncEnumerator", "Extensions.GetAsyncEnumerator(int)", "int").WithLocation(10, 33),
// (10,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(10, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithNullableValueTypeConversion()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in 1)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this int? self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS1929: 'int' does not contain a definition for 'GetAsyncEnumerator' and the best extension method overload 'Extensions.GetAsyncEnumerator(int?)' requires a receiver of type 'int?'
// await foreach (var i in 1)
Diagnostic(ErrorCode.ERR_BadInstanceArgType, "1").WithArguments("int", "GetAsyncEnumerator", "Extensions.GetAsyncEnumerator(int?)", "int?").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'int' because 'int' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in 1)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "1").WithArguments("int", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithUnboxingConversion()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new object())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this int self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS1929: 'object' does not contain a definition for 'GetAsyncEnumerator' and the best extension method overload 'Extensions.GetAsyncEnumerator(int)' requires a receiver of type 'int'
// await foreach (var i in new object())
Diagnostic(ErrorCode.ERR_BadInstanceArgType, "new object()").WithArguments("object", "GetAsyncEnumerator", "Extensions.GetAsyncEnumerator(int)", "int").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'object' because 'object' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new object())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new object()").WithArguments("object", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithNullableUnwrapping()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in (int?)1)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this int self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS1929: 'int?' does not contain a definition for 'GetAsyncEnumerator' and the best extension method overload 'Extensions.GetAsyncEnumerator(int)' requires a receiver of type 'int'
// await foreach (var i in (int?)1)
Diagnostic(ErrorCode.ERR_BadInstanceArgType, "(int?)1").WithArguments("int?", "GetAsyncEnumerator", "Extensions.GetAsyncEnumerator(int)", "int").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'int?' because 'int?' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in (int?)1)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "(int?)1").WithArguments("int?", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithZeroToEnumConversion()
{
var source = @"
using System;
using System.Threading.Tasks;
public enum E { Default = 0 }
public class C
{
public static async Task Main()
{
await foreach (var i in 0)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this E self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (9,33): error CS1929: 'int' does not contain a definition for 'GetAsyncEnumerator' and the best extension method overload 'Extensions.GetAsyncEnumerator(E)' requires a receiver of type 'E'
// await foreach (var i in 0)
Diagnostic(ErrorCode.ERR_BadInstanceArgType, "0").WithArguments("int", "GetAsyncEnumerator", "Extensions.GetAsyncEnumerator(E)", "E").WithLocation(9, 33),
// (9,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'int' because 'int' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in 0)
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "0").WithArguments("int", "GetAsyncEnumerator").WithLocation(9, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithUnconstrainedGenericConversion()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await Inner(1);
async Task Inner<T>(T t)
{
await foreach (var i in t)
{
Console.Write(i);
}
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithConstrainedGenericConversion()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await Inner(1);
async Task Inner<T>(T t) where T : IConvertible
{
await foreach (var i in t)
{
Console.Write(i);
}
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this IConvertible self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithFormattableStringConversion1()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in $"" "")
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this FormattableString self) => throw null;
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithFormattableStringConversion2()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in $"" "")
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this string self) => new C.Enumerator();
public static C.Enumerator GetAsyncEnumerator(this FormattableString self) => throw null;
public static C.Enumerator GetAsyncEnumerator(this object self) => throw null;
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithFormattableStringConversion3()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in $"" "")
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this FormattableString self) => throw null;
}";
CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS1929: 'string' does not contain a definition for 'GetAsyncEnumerator' and the best extension method overload 'Extensions.GetAsyncEnumerator(FormattableString)' requires a receiver of type 'FormattableString'
// await foreach (var i in $" ")
Diagnostic(ErrorCode.ERR_BadInstanceArgType, @"$"" """).WithArguments("string", "GetAsyncEnumerator", "Extensions.GetAsyncEnumerator(System.FormattableString)", "System.FormattableString").WithLocation(8, 33),
// (8,33): error CS8415: Asynchronous foreach statement cannot operate on variables of type 'string' because 'string' does not contain a public instance or extension definition for 'GetAsyncEnumerator'. Did you mean 'foreach' rather than 'await foreach'?
// await foreach (var i in $" ")
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMemberWrongAsync, @"$"" """).WithArguments("string", "GetAsyncEnumerator").WithLocation(8, 33));
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithDelegateConversion()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in () => 42)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this Func<int> self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS0446: Foreach cannot operate on a 'lambda expression'. Did you intend to invoke the 'lambda expression'?
// await foreach (var i in () => 42)
Diagnostic(ErrorCode.ERR_AnonMethGrpInForEach, "() => 42").WithArguments("lambda expression").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithBoxing()
{
string source = @"
using System;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnInterface()
{
var source = @"
using System;
using System.Threading.Tasks;
public interface I {}
public class C : I
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this I self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnDelegate()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in (Func<int>)(() => 42))
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this Func<int> self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnEnum()
{
var source = @"
using System;
using System.Threading.Tasks;
public enum E { Default }
public class C
{
public static async Task Main()
{
await foreach (var i in E.Default)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this E self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnNullable()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in (int?)null)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this int? self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnConstantNullObject()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in (object)null)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this object self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnTypeParameter()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new object())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator<T>(this T self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternOnRange()
{
var source = @"
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in 1..4)
{
Console.Write(i);
}
}
}
public static class Extensions
{
public static async IAsyncEnumerator<int> GetAsyncEnumerator(this Range range)
{
await Task.Yield();
for(var i = range.Start.Value; i < range.End.Value; i++)
{
yield return i;
}
}
}";
var comp = CreateCompilationWithTasksExtensions(
new[] { source, TestSources.Index, TestSources.Range, AsyncStreamsTypes },
options: TestOptions.DebugExe,
parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnTuple()
{
var source = @"
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
await foreach (var i in (1, 2, 3))
{
Console.Write(i);
}
}
}
public static class Extensions
{
public static async IAsyncEnumerator<T> GetAsyncEnumerator<T>(this (T first, T second, T third) self)
{
await Task.Yield();
yield return self.first;
yield return self.second;
yield return self.third;
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsOnTupleWithNestedConversions()
{
var source = @"
using System;
using System.Globalization;
using System.Linq;
using System.Collections.Generic;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
await foreach (var (a, b) in (new[] { 1, 2, 3 }, new List<decimal>{ 0.1m, 0.2m, 0.3m }))
{
Console.WriteLine((a + b).ToString(CultureInfo.InvariantCulture));
}
}
}
public static class Extensions
{
public static async IAsyncEnumerator<(T1, T2)> GetAsyncEnumerator<T1, T2>(this (IEnumerable<T1> first, IEnumerable<T2> second) self)
{
await Task.Yield();
foreach(var pair in self.first.Zip(self.second, (a,b) => (a,b)))
{
yield return pair;
}
}
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: @"1.1
2.2
3.3");
}
[Fact]
public void TestMoveNextAsyncPatternViaExtensions1()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
public static bool MoveNext(this C.Enumerator e) => false;
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): error CS0117: 'C.Enumerator' does not contain a definition for 'MoveNextAsync'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("C.Enumerator", "MoveNextAsync").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'Extensions.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "Extensions.GetAsyncEnumerator(C)").WithLocation(8, 33)
);
}
[Fact]
public void TestMoveNextAsyncPatternViaExtensions2()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
}
public C.Enumerator GetAsyncEnumerator() => new C.Enumerator();
}
public static class Extensions
{
public static bool MoveNext(this C.Enumerator e) => false;
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): error CS0117: 'C.Enumerator' does not contain a definition for 'MoveNextAsync'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("C.Enumerator", "MoveNextAsync").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "C.GetAsyncEnumerator()").WithLocation(8, 33)
);
}
[Fact]
public void TestPreferAsyncEnumeratorPatternFromInstanceThanViaExtension()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator1
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
public sealed class Enumerator2
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => throw null;
}
public C.Enumerator1 GetAsyncEnumerator() => new C.Enumerator1();
}
public static class Extensions
{
public static C.Enumerator2 GetAsyncEnumerator(this C self) => throw null;
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestPreferAsyncEnumeratorPatternFromInstanceThanViaExtensionEvenWhenInvalid()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator1
{
}
public sealed class Enumerator2
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => throw null;
}
public C.Enumerator1 GetAsyncEnumerator() => throw null;
}
public static class Extensions
{
public static C.Enumerator2 GetAsyncEnumerator(this C self) => throw null;
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): error CS0117: 'C.Enumerator1' does not contain a definition for 'Current'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("C.Enumerator1", "Current").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator1' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator1", "C.GetAsyncEnumerator()").WithLocation(8, 33));
}
[Fact]
public void TestPreferAsyncEnumeratorPatternFromIAsyncEnumerableInterfaceThanViaExtension()
{
string source = @"
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
public class C : IAsyncEnumerable<int>
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator1 : IAsyncEnumerator<int>
{
public int Current { get; private set; }
public ValueTask<bool> MoveNextAsync() => new ValueTask<bool>(Current++ != 3);
public ValueTask DisposeAsync() => new ValueTask();
}
public sealed class Enumerator2
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => throw null;
}
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(CancellationToken cancellationToken) => new C.Enumerator1();
}
public static class Extensions
{
public static C.Enumerator2 GetAsyncEnumerator(this C self) => throw null;
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestCannotUseExtensionGetAsyncEnumeratorOnDynamic()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in (dynamic)new C())
{
Console.Write(i);
}
}
public sealed class Enumerator2
{
public int Current { get; private set; }
public bool MoveNext() => throw null;
}
}
public static class Extensions
{
public static C.Enumerator2 GetAsyncEnumerator(this C self) => throw null;
}";
CreateCompilationWithCSharp(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (9,33): error CS8416: Cannot use a collection of dynamic type in an asynchronous foreach
// await foreach (var i in (dynamic)new C())
Diagnostic(ErrorCode.ERR_BadDynamicAwaitForEach, "(dynamic)new C()").WithLocation(9, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensions()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): warning CS0278: 'C' does not implement the 'collection' pattern. 'Extensions1.GetAsyncEnumerator(C)' is ambiguous with 'Extensions2.GetAsyncEnumerator(C)'.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternIsAmbiguous, "new C()").WithArguments("C", "collection", "Extensions1.GetAsyncEnumerator(C)", "Extensions2.GetAsyncEnumerator(C)").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWhenOneHasCorrectPattern()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static int GetAsyncEnumerator(this C self) => 42;
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): warning CS0278: 'C' does not implement the 'collection' pattern. 'Extensions1.GetAsyncEnumerator(C)' is ambiguous with 'Extensions2.GetAsyncEnumerator(C)'.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternIsAmbiguous, "new C()").WithArguments("C", "collection", "Extensions1.GetAsyncEnumerator(C)", "Extensions2.GetAsyncEnumerator(C)").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWhenNeitherHasCorrectPattern()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static int GetAsyncEnumerator(this C self) => 42;
}
public static class Extensions2
{
public static bool GetAsyncEnumerator(this C self) => true;
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): warning CS0278: 'C' does not implement the 'collection' pattern. 'Extensions1.GetAsyncEnumerator(C)' is ambiguous with 'Extensions2.GetAsyncEnumerator(C)'.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternIsAmbiguous, "new C()").WithArguments("C", "collection", "Extensions1.GetAsyncEnumerator(C)", "Extensions2.GetAsyncEnumerator(C)").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWhenOneHasCorrectNumberOfParameters()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this C self, int _) => throw null;
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWhenNeitherHasCorrectNumberOfParameters()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this C self, int _) => new C.Enumerator();
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self, bool _) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS1501: No overload for method 'GetAsyncEnumerator' takes 0 arguments
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadArgCount, "new C()").WithArguments("GetAsyncEnumerator", "0").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsOnDifferentInterfaces()
{
var source = @"
using System;
using System.Threading.Tasks;
public interface I1 {}
public interface I2 {}
public class C : I1, I2
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this I1 self) => new C.Enumerator();
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this I2 self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (12,33): warning CS0278: 'C' does not implement the 'collection' pattern. 'Extensions1.GetAsyncEnumerator(I1)' is ambiguous with 'Extensions2.GetAsyncEnumerator(I2)'.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternIsAmbiguous, "new C()").WithArguments("C", "collection", "Extensions1.GetAsyncEnumerator(I1)", "Extensions2.GetAsyncEnumerator(I2)").WithLocation(12, 33),
// (12,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(12, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWithMostSpecificReceiver()
{
var source = @"
using System;
using System.Threading.Tasks;
public interface I {}
public class C : I
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this I self) => throw null;
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWithMostSpecificReceiverWhenMostSpecificReceiverDoesntImplementPattern()
{
var source = @"
using System;
using System.Threading.Tasks;
public interface I {}
public class C : I
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this I self) => throw null;
}
public static class Extensions2
{
public static int GetAsyncEnumerator(this C self) => 42;
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (10,33): error CS0117: 'int' does not contain a definition for 'Current'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("int", "Current").WithLocation(10, 33),
// (10,33): error CS8412: Asynchronous foreach requires that the return type 'int' of 'Extensions2.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("int", "Extensions2.GetAsyncEnumerator(C)").WithLocation(10, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWhenOneHasOptionalParams()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self, int a = 0) => throw null;
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAmbiguousExtensionsWhenOneHasFewerOptionalParams()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions1
{
public static C.Enumerator GetAsyncEnumerator(this C self, int a = 0, int b = 1) => new C.Enumerator();
}
public static class Extensions2
{
public static C.Enumerator GetAsyncEnumerator(this C self, int a = 0) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): warning CS0278: 'C' does not implement the 'collection' pattern. 'Extensions1.GetAsyncEnumerator(C, int, int)' is ambiguous with 'Extensions2.GetAsyncEnumerator(C, int)'.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternIsAmbiguous, "new C()").WithArguments("C", "collection", "Extensions1.GetAsyncEnumerator(C, int, int)", "Extensions2.GetAsyncEnumerator(C, int)").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithOptionalParameter()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public Enumerator(int start) => Current = start;
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self, int x = 1) => new C.Enumerator(x);
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "23");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithArgList()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self, __arglist) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS7036: There is no argument given that corresponds to the required parameter '__arglist' of 'Extensions.GetAsyncEnumerator(C, __arglist)'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoCorrespondingArgument, "new C()").WithArguments("__arglist", "Extensions.GetAsyncEnumerator(C, __arglist)").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithParams()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public Enumerator(int[] arr) => Current = arr.Length;
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self, params int[] x) => new C.Enumerator(x);
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaRefExtensionOnNonAssignableVariable()
{
string source = @"
using System;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this ref C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): error CS1510: A ref or out value must be an assignable variable
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_RefLvalueExpected, "new C()").WithLocation(8, 33));
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaRefExtensionOnAssignableVariable()
{
string source = @"
using System;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
var c = new C();
await foreach (var i in c)
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this ref C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (9,33): error CS1510: A ref or out value must be an assignable variable
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_RefLvalueExpected, "c").WithLocation(9, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaOutExtension()
{
string source = @"
using System;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this out C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): error CS1620: Argument 1 must be passed with the 'out' keyword
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadArgRef, "new C()").WithArguments("1", "out").WithLocation(8, 33),
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33),
// (21,56): error CS8328: The parameter modifier 'out' cannot be used with 'this'
// public static C.Enumerator GetAsyncEnumerator(this out C self) => new C.Enumerator();
Diagnostic(ErrorCode.ERR_BadParameterModifiers, "out").WithArguments("out", "this").WithLocation(21, 56));
}
[Theory]
[InlineData("in", LanguageVersion.CSharp9)]
[InlineData("ref readonly", LanguageVersion.Preview)]
public void TestGetAsyncEnumeratorPatternViaInExtensionOnNonAssignableVariable(string modifier, LanguageVersion languageVersion)
{
string source = @"
using System;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this " + modifier + @" C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular.WithLanguageVersion(languageVersion));
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Theory]
[InlineData("in", LanguageVersion.CSharp9)]
[InlineData("ref readonly", LanguageVersion.Preview)]
public void TestGetAsyncEnumeratorPatternViaInExtensionOnAssignableVariable(string modifier, LanguageVersion languageVersion)
{
string source = @"
using System;
using System.Threading.Tasks;
public struct C
{
public static async Task Main()
{
var c = new C();
await foreach (var i in c)
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this " + modifier + @" C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular.WithLanguageVersion(languageVersion));
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsCSharp8()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular8);
comp.VerifyDiagnostics(
// (8,33): error CS8400: Feature 'extension GetAsyncEnumerator' is not available in C# 8.0. Please use language version 9.0 or greater.
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion8, "new C()").WithArguments("extension GetAsyncEnumerator", "9.0").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaInternalExtensions()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
internal static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionInInternalClass()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
internal static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithInvalidEnumerator()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
}
}
internal static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS0117: 'C.Enumerator' does not contain a definition for 'MoveNextAsync'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("C.Enumerator", "MoveNextAsync").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator' of 'Extensions.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator", "Extensions.GetAsyncEnumerator(C)").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithInstanceGetAsyncEnumeratorReturningTypeWhichDoesntMatchPattern()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator1
{
public int Current { get; private set; }
}
public sealed class Enumerator2
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
public Enumerator1 GetAsyncEnumerator() => new Enumerator1();
}
internal static class Extensions
{
public static C.Enumerator2 GetAsyncEnumerator(this C self) => new C.Enumerator2();
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS0117: 'C.Enumerator1' does not contain a definition for 'MoveNextAsync'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("C.Enumerator1", "MoveNextAsync").WithLocation(8, 33),
// (8,33): error CS8412: Asynchronous foreach requires that the return type 'C.Enumerator1' of 'C.GetAsyncEnumerator()' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("C.Enumerator1", "C.GetAsyncEnumerator()").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithInternalInstanceGetAsyncEnumerator()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
internal Enumerator GetAsyncEnumerator() => throw null;
}
internal static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,33): warning CS0279: 'C' does not implement the 'async streams' pattern. 'C.GetAsyncEnumerator()' is not a public instance or extension method.
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_PatternNotPublicOrNotInstance, "new C()").WithArguments("C", "async streams", "C.GetAsyncEnumerator()").WithLocation(8, 33)
);
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithInstanceGetAsyncEnumeratorWithTooManyParameters()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
internal Enumerator GetAsyncEnumerator(int a) => throw null;
}
internal static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithStaticGetAsyncEnumeratorDeclaredInType()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
public static Enumerator GetAsyncEnumerator() => throw null;
}
internal static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestAwaitForEachViaExtensionImplicitImplementationOfIAsyncDisposableStruct()
{
var source = @"
using System;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var x in new C())
{
Console.Write(x);
}
}
}
static class Extensions
{
public static Enumerator GetAsyncEnumerator(this C _) => new Enumerator();
}
struct Enumerator : IAsyncDisposable
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
public ValueTask DisposeAsync() { Console.Write(""Disposed""); return new ValueTask(); }
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: @"123Disposed");
}
[Fact]
public void TestAwaitForEachViaExtensionExplicitlyDisposableStruct()
{
var source = @"
using System;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var x in new C())
{
Console.Write(x);
}
}
}
static class Extensions
{
public static Enumerator GetAsyncEnumerator(this C _) => new Enumerator();
}
struct Enumerator : IAsyncDisposable
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
ValueTask IAsyncDisposable.DisposeAsync() { Console.Write(""Disposed""); return new ValueTask(); }
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: @"123Disposed");
}
[Fact]
public void TestAwaitForEachViaExtensionAsyncDisposeStruct()
{
var source = @"
using System;
using System.Threading.Tasks;
class C
{
static async Task Main()
{
await foreach (var x in new C())
{
Console.Write(x);
}
}
}
static class Extensions
{
public static Enumerator GetAsyncEnumerator(this C _) => new Enumerator();
}
struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
public ValueTask DisposeAsync() { Console.Write(""Disposed""); return new ValueTask(); }
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: @"123Disposed");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionsWithTaskLikeTypeMoveNext()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public ValueTask<bool> MoveNextAsync() => new ValueTask<bool>(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestWithObsoletePatternMethodsViaExtension()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
[Obsolete]
public int Current { get; private set; }
[Obsolete]
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
[Obsolete]
public Task DisposeAsync() { Console.Write(""Disposed""); return Task.CompletedTask; }
}
}
[Obsolete]
public static class Extensions
{
[Obsolete]
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (8,15): warning CS0612: 'Extensions.GetAsyncEnumerator(C)' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("Extensions.GetAsyncEnumerator(C)").WithLocation(8, 15),
// (8,15): warning CS0612: 'C.Enumerator.MoveNextAsync()' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.Enumerator.MoveNextAsync()").WithLocation(8, 15),
// (8,15): warning CS0612: 'C.Enumerator.Current' is obsolete
// await foreach (var i in new C())
Diagnostic(ErrorCode.WRN_DeprecatedSymbol, "foreach").WithArguments("C.Enumerator.Current").WithLocation(8, 15)
);
CompileAndVerify(comp, expectedOutput: "123Disposed");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaImportedExtensions()
{
string source = @"
using System;
using System.Threading.Tasks;
using N;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
namespace N
{
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaUnimportedExtensions()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
namespace N
{
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
}";
CreateCompilationWithMscorlib46(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestWithPatternGetAsyncEnumeratorViaExtensionOnUnassignedCollection()
{
string source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
C c;
await foreach (var i in c)
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (9,33): error CS0165: Use of unassigned local variable 'c'
// await foreach (var i in c)
Diagnostic(ErrorCode.ERR_UseDefViolation, "c").WithArguments("c").WithLocation(9, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaValidExtensionInClosestNamespaceInvalidInFurtherNamespace1()
{
var source = @"
using System;
using System.Threading.Tasks;
using N1.N2.N3;
namespace N1
{
public static class Extensions
{
public static int GetAsyncEnumerator(this C self) => throw null;
}
namespace N2
{
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
namespace N3
{
using N2;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
}
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaValidExtensionInClosestNamespaceInvalidInFurtherNamespace2()
{
var source = @"
using System;
using System.Threading.Tasks;
using N1;
using N3;
namespace N1
{
using N2;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
}
namespace N2
{
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
}
namespace N3
{
public static class Extensions
{
public static int GetAsyncEnumerator(this C self) => throw null;
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics(
// (5,1): hidden CS8019: Unnecessary using directive.
// using N3;
Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using N3;").WithLocation(5, 1));
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaInvalidExtensionInClosestNamespaceValidInFurtherNamespace1()
{
var source = @"
using System;
using System.Threading.Tasks;
using N1.N2.N3;
namespace N1
{
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
namespace N2
{
public static class Extensions
{
public static int GetAsyncEnumerator(this C self) => throw null;
}
namespace N3
{
using N2;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
}
}
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (27,45): error CS0117: 'int' does not contain a definition for 'Current'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("int", "Current").WithLocation(27, 45),
// (27,45): error CS8412: Asynchronous foreach requires that the return type 'int' of 'Extensions.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("int", "N1.N2.Extensions.GetAsyncEnumerator(N1.N2.N3.C)").WithLocation(27, 45));
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaInvalidExtensionInClosestNamespaceValidInFurtherNamespace2()
{
var source = @"
using System;
using System.Threading.Tasks;
using N1;
using N2;
namespace N1
{
using N3;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
}
namespace N2
{
public static class Extensions
{
public static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
}
namespace N3
{
public static class Extensions
{
public static int GetAsyncEnumerator(this C self) => throw null;
}
}";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (5,1): hidden CS8019: Unnecessary using directive.
// using N2;
Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using N2;").WithLocation(5, 1),
// (14,37): error CS0117: 'int' does not contain a definition for 'Current'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_NoSuchMember, "new C()").WithArguments("int", "Current").WithLocation(14, 37),
// (14,37): error CS8412: Asynchronous foreach requires that the return type 'int' of 'Extensions.GetAsyncEnumerator(C)' must have a suitable public 'MoveNextAsync' method and public 'Current' property
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_BadGetAsyncEnumerator, "new C()").WithArguments("int", "N3.Extensions.GetAsyncEnumerator(N1.C)").WithLocation(14, 37));
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAccessiblePrivateExtension()
{
var source = @"
using System;
using System.Threading.Tasks;
public static class Program
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
private static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
public class C
{
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaAccessiblePrivateExtensionInNestedClass()
{
var source = @"
using System;
using System.Threading.Tasks;
public static class Program
{
public static class Inner
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
}
private static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
public class C
{
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123");
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaInaccessiblePrivateExtension()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
}
public sealed class Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
private static C.Enumerator GetAsyncEnumerator(this C self) => new C.Enumerator();
}
";
CreateCompilation(source, parseOptions: TestOptions.Regular9)
.VerifyDiagnostics(
// (8,33): error CS8411: Asynchronous foreach statement cannot operate on variables of type 'C' because 'C' does not contain a suitable public instance or extension definition for 'GetAsyncEnumerator'
// await foreach (var i in new C())
Diagnostic(ErrorCode.ERR_AwaitForEachMissingMember, "new C()").WithArguments("C", "GetAsyncEnumerator").WithLocation(8, 33)
);
}
[Fact]
public void TestGetAsyncEnumeratorPatternViaExtensionWithRefReturn()
{
var source = @"
using System;
using System.Threading.Tasks;
public class C
{
public static async Task Main()
{
await foreach (var i in new C())
{
Console.Write(i);
}
await foreach (var i in new C())
{
Console.Write(i);
}
}
public struct Enumerator
{
public int Current { get; private set; }
public Task<bool> MoveNextAsync() => Task.FromResult(Current++ != 3);
}
}
public static class Extensions
{
public static C.Enumerator Instance = new C.Enumerator();
public static ref C.Enumerator GetAsyncEnumerator(this C self) => ref Instance;
}";
var comp = CreateCompilationWithMscorlib46(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular9);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "123123");
}
[Theory, WorkItem(59955, "https://github.com/dotnet/roslyn/issues/59955")]
[InlineData(true)]
[InlineData(false)]
public void DisposePatternPreferredOverIAsyncDisposable(bool withCSharp8)
{
var source = @"
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new AsyncEnumerable())
{
}
}
}
struct AsyncEnumerable : IAsyncEnumerable<int>
{
public AsyncEnumerator GetAsyncEnumerator(CancellationToken token = default) => new AsyncEnumerator();
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(CancellationToken token) => throw null;
}
struct AsyncEnumerator : IAsyncEnumerator<int>
{
public int Current => 0;
public async ValueTask<bool> MoveNextAsync()
{
await Task.Yield();
return false;
}
public async ValueTask DisposeAsync()
{
Console.WriteLine(""RAN"");
await Task.Yield();
}
int IAsyncEnumerator<int>.Current => throw null;
ValueTask<bool> IAsyncEnumerator<int>.MoveNextAsync() => throw null;
ValueTask IAsyncDisposable.DisposeAsync() => throw null;
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe,
parseOptions: withCSharp8 ? TestOptions.Regular8 : TestOptions.Regular7_3);
if (withCSharp8)
{
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "RAN");
}
else
{
comp.VerifyDiagnostics(
// (11,9): error CS8370: Feature 'async streams' is not available in C# 7.3. Please use language version 8.0 or greater.
// await foreach (var i in new AsyncEnumerable())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "await").WithArguments("async streams", "8.0").WithLocation(11, 9)
);
}
var tree = comp.SyntaxTrees.First();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.True(info.IsAsynchronous);
Assert.Equal("AsyncEnumerator AsyncEnumerable.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> AsyncEnumerator.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 AsyncEnumerator.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask AsyncEnumerator.DisposeAsync()",
info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
}
[Theory, WorkItem(59955, "https://github.com/dotnet/roslyn/issues/59955")]
[InlineData(true)]
[InlineData(false)]
public void DisposePatternPreferredOverIAsyncDisposable_NoIAsyncEnumerable(bool withCSharp8)
{
var source = @"
using System;
using System.Threading;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new AsyncEnumerable())
{
}
}
}
struct AsyncEnumerable
{
public AsyncEnumerator GetAsyncEnumerator(CancellationToken token = default) => new AsyncEnumerator();
}
struct AsyncEnumerator : IAsyncDisposable
{
public int Current => 0;
public async ValueTask<bool> MoveNextAsync()
{
await Task.Yield();
return false;
}
public async ValueTask DisposeAsync()
{
Console.WriteLine(""RAN"");
await Task.Yield();
}
ValueTask IAsyncDisposable.DisposeAsync() => throw null;
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe,
parseOptions: withCSharp8 ? TestOptions.Regular8 : TestOptions.Regular7_3);
if (withCSharp8)
{
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "RAN");
}
else
{
comp.VerifyDiagnostics(
// (10,9): error CS8370: Feature 'async streams' is not available in C# 7.3. Please use language version 8.0 or greater.
// await foreach (var i in new AsyncEnumerable())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "await").WithArguments("async streams", "8.0").WithLocation(10, 9)
);
}
var tree = comp.SyntaxTrees.First();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.True(info.IsAsynchronous);
Assert.Equal("AsyncEnumerator AsyncEnumerable.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> AsyncEnumerator.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 AsyncEnumerator.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask AsyncEnumerator.DisposeAsync()",
info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
}
[Theory, WorkItem(59955, "https://github.com/dotnet/roslyn/issues/59955")]
[InlineData(true)]
[InlineData(false)]
public void AsyncEnumerationViaInterfaceUsesIAsyncDisposable(bool withCSharp8)
{
// The enumerator type is IAsyncEnumerator<int> so disposal uses IAsyncDisposable.DisposeAsync()
var source = @"
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var i in new AsyncEnumerable())
{
}
}
}
struct AsyncEnumerable : IAsyncEnumerable<int>
{
IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(CancellationToken token) => new AsyncEnumerator();
}
struct AsyncEnumerator : IAsyncEnumerator<int>
{
public ValueTask DisposeAsync() => throw null;
int IAsyncEnumerator<int>.Current => 0;
async ValueTask<bool> IAsyncEnumerator<int>.MoveNextAsync()
{
await Task.Yield();
return false;
}
async ValueTask IAsyncDisposable.DisposeAsync()
{
Console.WriteLine(""RAN"");
await Task.Yield();
}
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe,
parseOptions: withCSharp8 ? TestOptions.Regular8 : TestOptions.Regular7_3);
if (withCSharp8)
{
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "RAN");
}
else
{
comp.VerifyDiagnostics(
// (11,9): error CS8370: Feature 'async streams' is not available in C# 7.3. Please use language version 8.0 or greater.
// await foreach (var i in new AsyncEnumerable())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "await").WithArguments("async streams", "8.0").WithLocation(11, 9)
);
}
var tree = comp.SyntaxTrees.First();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.True(info.IsAsynchronous);
Assert.Equal("System.Collections.Generic.IAsyncEnumerator<System.Int32> System.Collections.Generic.IAsyncEnumerable<System.Int32>.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> System.Collections.Generic.IAsyncEnumerator<System.Int32>.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("System.Int32 System.Collections.Generic.IAsyncEnumerator<System.Int32>.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()",
info.DisposeMethod.ToTestDisplayString());
Assert.Equal("System.Int32", info.ElementType.ToTestDisplayString());
}
[Fact, WorkItem(59955, "https://github.com/dotnet/roslyn/issues/59955")]
public void EnumerationViaInterfaceUsesIDisposable()
{
var source = @"
using System;
using System.Collections;
using System.Collections.Generic;
class C
{
public static void Main()
{
foreach (var i in new Enumerable())
{
}
}
}
struct Enumerable : IEnumerable<int>
{
IEnumerator IEnumerable.GetEnumerator() => throw null;
IEnumerator<int> IEnumerable<int>.GetEnumerator() => new Enumerator();
}
struct Enumerator : IEnumerator<int>
{
public void Dispose() => throw null;
int IEnumerator<int>.Current => 0;
object IEnumerator.Current => throw null;
void IEnumerator.Reset() => throw null;
bool IEnumerator.MoveNext() => false;
void IDisposable.Dispose()
{
Console.WriteLine(""RAN"");
}
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe);
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "RAN");
var tree = comp.SyntaxTrees.First();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.Equal("void System.IDisposable.Dispose()", info.DisposeMethod.ToTestDisplayString());
}
[Theory, WorkItem(59955, "https://github.com/dotnet/roslyn/issues/59955")]
[InlineData(true)]
[InlineData(false)]
public void DisposePatternPreferredOverIAsyncDisposable_Deconstruction(bool withCSharp8)
{
var source = @"
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
class C
{
public static async Task Main()
{
await foreach (var (i, j) in new AsyncEnumerable())
{
}
}
}
struct AsyncEnumerable : IAsyncEnumerable<(int, int)>
{
public AsyncEnumerator GetAsyncEnumerator(CancellationToken token = default) => new AsyncEnumerator();
IAsyncEnumerator<(int, int)> IAsyncEnumerable<(int, int)>.GetAsyncEnumerator(CancellationToken token) => throw null;
}
struct AsyncEnumerator : IAsyncEnumerator<(int, int)>
{
public (int, int) Current => (0, 0);
public async ValueTask<bool> MoveNextAsync()
{
await Task.Yield();
return false;
}
public async ValueTask DisposeAsync()
{
Console.WriteLine(""RAN"");
await Task.Yield();
}
(int, int) IAsyncEnumerator<(int, int)>.Current => throw null;
ValueTask<bool> IAsyncEnumerator<(int, int)>.MoveNextAsync() => throw null;
ValueTask IAsyncDisposable.DisposeAsync() => throw null;
}
";
var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, options: TestOptions.DebugExe,
parseOptions: withCSharp8 ? TestOptions.Regular8 : TestOptions.Regular7_3);
if (withCSharp8)
{
comp.VerifyDiagnostics();
CompileAndVerify(comp, expectedOutput: "RAN");
}
else
{
comp.VerifyDiagnostics(
// (11,9): error CS8370: Feature 'async streams' is not available in C# 7.3. Please use language version 8.0 or greater.
// await foreach (var i in new AsyncEnumerable())
Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "await").WithArguments("async streams", "8.0").WithLocation(11, 9)
);
}
var tree = comp.SyntaxTrees.First();
var model = comp.GetSemanticModel(tree, ignoreAccessibility: false);
var foreachSyntax = tree.GetRoot().DescendantNodes().OfType<ForEachVariableStatementSyntax>().Single();
var info = model.GetForEachStatementInfo(foreachSyntax);
Assert.True(info.IsAsynchronous);
Assert.Equal("AsyncEnumerator AsyncEnumerable.GetAsyncEnumerator([System.Threading.CancellationToken token = default(System.Threading.CancellationToken)])",
info.GetEnumeratorMethod.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask<System.Boolean> AsyncEnumerator.MoveNextAsync()",
info.MoveNextMethod.ToTestDisplayString());
Assert.Equal("(System.Int32, System.Int32) AsyncEnumerator.Current { get; }",
info.CurrentProperty.ToTestDisplayString());
Assert.Equal("System.Threading.Tasks.ValueTask AsyncEnumerator.DisposeAsync()",
info.DisposeMethod.ToTestDisplayString());
Assert.Equal("(System.Int32, System.Int32)", info.ElementType.ToTestDisplayString());
}
[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/72819")]
public void PatternBasedFails_AwaitForeach()
{
var src = """
using System;
using System.Threading;
using System.Threading.Tasks;
interface ICustomEnumerator
{
public int Current {get;}
public ValueTask<bool> MoveNextAsync();
}
interface IGetEnumerator<TEnumerator> where TEnumerator : ICustomEnumerator
{
TEnumerator GetAsyncEnumerator(CancellationToken token = default);
}
struct S1 : IGetEnumerator<S2>
{
public S2 GetAsyncEnumerator(CancellationToken token = default)
{
return new S2();
}
}
interface IMyAsyncDisposable1
{
ValueTask DisposeAsync();
}
interface IMyAsyncDisposable2
{
ValueTask DisposeAsync();
}
struct S2 : ICustomEnumerator, IMyAsyncDisposable1, IMyAsyncDisposable2, IAsyncDisposable
{
ValueTask IMyAsyncDisposable1.DisposeAsync() => throw null;
ValueTask IMyAsyncDisposable2.DisposeAsync() => throw null;
public ValueTask DisposeAsync()
{
System.Console.Write("D");
return ValueTask.CompletedTask;
}
public int Current => throw null;
public ValueTask<bool> MoveNextAsync()
{
return ValueTask.FromResult(false);
}
}
class C
{
static async Task Main()
{
await Test<S1, S2>();
}
static async Task Test<TEnumerable, TEnumerator>()
where TEnumerable : IGetEnumerator<TEnumerator>
where TEnumerator : ICustomEnumerator, IMyAsyncDisposable1, IMyAsyncDisposable2, IAsyncDisposable
{
await foreach (var i in default(TEnumerable))
{
System.Console.Write(i);
}
}
}
""";
var comp = CreateCompilation(src, targetFramework: TargetFramework.Net80, options: TestOptions.ReleaseExe);
CompileAndVerify(comp,
expectedOutput: ExecutionConditionUtil.IsMonoOrCoreClr ? "D" : null,
verify: ExecutionConditionUtil.IsMonoOrCoreClr ? Verification.Passes : Verification.Skipped).VerifyDiagnostics();
}
}
}
|