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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.
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Threading;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
[assembly: System.Resources.NeutralResourcesLanguage("en-US")]
namespace Microsoft.Interop
{
[Generator]
public sealed class DownlevelLibraryImportGenerator : IIncrementalGenerator
{
internal sealed record IncrementalStubGenerationContext(
SignatureContext SignatureContext,
ContainingSyntaxContext ContainingSyntaxContext,
ContainingSyntax StubMethodSyntaxTemplate,
MethodSignatureDiagnosticLocations DiagnosticLocation,
SequenceEqualImmutableArray<AttributeSyntax> ForwardedAttributes,
LibraryImportData LibraryImportData,
EnvironmentFlags EnvironmentFlags,
SequenceEqualImmutableArray<DiagnosticInfo> Diagnostics);
public static class StepNames
{
public const string CalculateStubInformation = nameof(CalculateStubInformation);
public const string GenerateSingleStub = nameof(GenerateSingleStub);
}
public void Initialize(IncrementalGeneratorInitializationContext context)
{
// Collect all methods adorned with LibraryImportAttribute
var attributedMethods = context.SyntaxProvider
.ForAttributeWithMetadataName(
TypeNames.LibraryImportAttribute,
static (node, ct) => node is MethodDeclarationSyntax,
static (context, ct) => context.TargetSymbol is IMethodSymbol methodSymbol
? new { Syntax = (MethodDeclarationSyntax)context.TargetNode, Symbol = methodSymbol }
: null)
.Where(
static modelData => modelData is not null);
// Validate if attributed methods can have source generated
var methodsWithDiagnostics = attributedMethods.Select(static (data, ct) =>
{
DiagnosticInfo? diagnostic = GetDiagnosticIfInvalidMethodForGeneration(data.Syntax, data.Symbol);
return diagnostic is not null
? DiagnosticOr<(MethodDeclarationSyntax Syntax, IMethodSymbol Symbol)>.From(diagnostic)
: DiagnosticOr<(MethodDeclarationSyntax Syntax, IMethodSymbol Symbol)>.From((data.Syntax, data.Symbol));
});
var methodsToGenerate = context.FilterAndReportDiagnostics(methodsWithDiagnostics);
IncrementalValueProvider<StubEnvironment> stubEnvironment = context.CreateStubEnvironmentProvider();
IncrementalValuesProvider<(MemberDeclarationSyntax, ImmutableArray<DiagnosticInfo>)> generateSingleStub = methodsToGenerate
.Combine(stubEnvironment)
.Select(static (data, ct) => new
{
data.Left.Syntax,
data.Left.Symbol,
Environment = data.Right,
})
.Select(
static (data, ct) => CalculateStubInformation(data.Syntax, data.Symbol, data.Environment, ct)
)
.WithTrackingName(StepNames.CalculateStubInformation)
.Select(
static (data, ct) => GenerateSource(data)
)
.WithComparer(Comparers.GeneratedSyntax)
.WithTrackingName(StepNames.GenerateSingleStub);
context.RegisterDiagnostics(generateSingleStub.SelectMany((stubInfo, ct) => stubInfo.Item2));
context.RegisterConcatenatedSyntaxOutputs(generateSingleStub.Select((data, ct) => data.Item1), "LibraryImports.g.cs");
}
private static List<AttributeSyntax> GenerateSyntaxForForwardedAttributes(AttributeData? defaultDllImportSearchPathsAttribute)
{
// Manually rehydrate the forwarded attributes with fully qualified types so we don't have to worry about any using directives.
List<AttributeSyntax> attributes = [];
if (defaultDllImportSearchPathsAttribute is not null)
{
attributes.Add(
Attribute(NameSyntaxes.DefaultDllImportSearchPathsAttribute).AddArgumentListArguments(
AttributeArgument(
CastExpression(TypeSyntaxes.DllImportSearchPath,
LiteralExpression(SyntaxKind.NumericLiteralExpression,
Literal((int)defaultDllImportSearchPathsAttribute.ConstructorArguments[0].Value!))))));
}
return attributes;
}
private static SyntaxTokenList StripTriviaFromModifiers(SyntaxTokenList tokenList)
{
SyntaxToken[] strippedTokens = new SyntaxToken[tokenList.Count];
for (int i = 0; i < tokenList.Count; i++)
{
strippedTokens[i] = tokenList[i].WithoutTrivia();
}
return new SyntaxTokenList(strippedTokens);
}
private static MethodDeclarationSyntax PrintGeneratedSource(
ContainingSyntax userDeclaredMethod,
SignatureContext stub,
BlockSyntax stubCode)
{
// Create stub function
return MethodDeclaration(stub.StubReturnType, userDeclaredMethod.Identifier)
.AddAttributeLists(stub.AdditionalAttributes.ToArray())
.WithModifiers(StripTriviaFromModifiers(userDeclaredMethod.Modifiers))
.WithParameterList(ParameterList(SeparatedList(stub.StubParameters)))
.WithBody(stubCode);
}
private static LibraryImportCompilationData? ProcessLibraryImportAttribute(AttributeData attrData)
{
// Found the LibraryImport, but it has an error so report the error.
// This is most likely an issue with targeting an incorrect TFM.
if (attrData.AttributeClass?.TypeKind is null or TypeKind.Error)
{
return null;
}
if (attrData.ConstructorArguments.Length == 0)
{
return null;
}
ImmutableDictionary<string, TypedConstant> namedArguments = ImmutableDictionary.CreateRange(attrData.NamedArguments);
string? entryPoint = null;
if (namedArguments.TryGetValue(nameof(LibraryImportCompilationData.EntryPoint), out TypedConstant entryPointValue))
{
if (entryPointValue.Value is not string)
{
return null;
}
entryPoint = (string)entryPointValue.Value!;
}
return new LibraryImportCompilationData(attrData.ConstructorArguments[0].Value!.ToString())
{
EntryPoint = entryPoint,
}.WithValuesFromNamedArguments(namedArguments);
}
private static IncrementalStubGenerationContext CalculateStubInformation(
MethodDeclarationSyntax originalSyntax,
IMethodSymbol symbol,
StubEnvironment environment,
CancellationToken ct)
{
ct.ThrowIfCancellationRequested();
INamedTypeSymbol? lcidConversionAttrType = environment.LcidConversionAttrType;
INamedTypeSymbol? defaultDllImportSearchPathsAttrType = environment.DefaultDllImportSearchPathsAttrType;
// Get any attributes of interest on the method
AttributeData? generatedDllImportAttr = null;
AttributeData? lcidConversionAttr = null;
AttributeData? defaultDllImportSearchPathsAttribute = null;
foreach (AttributeData attr in symbol.GetAttributes())
{
if (attr.AttributeClass is not null
&& attr.AttributeClass.ToDisplayString() == TypeNames.LibraryImportAttribute)
{
generatedDllImportAttr = attr;
}
else if (lcidConversionAttrType is not null && SymbolEqualityComparer.Default.Equals(attr.AttributeClass, lcidConversionAttrType))
{
lcidConversionAttr = attr;
}
else if (defaultDllImportSearchPathsAttrType is not null && SymbolEqualityComparer.Default.Equals(attr.AttributeClass, defaultDllImportSearchPathsAttrType))
{
defaultDllImportSearchPathsAttribute = attr;
}
}
Debug.Assert(generatedDllImportAttr is not null);
var locations = new MethodSignatureDiagnosticLocations(originalSyntax);
var generatorDiagnostics = new GeneratorDiagnosticsBag(new DiagnosticDescriptorProvider(), locations, SR.ResourceManager, typeof(FxResources.Microsoft.Interop.LibraryImportGenerator.Downlevel.SR));
// Process the LibraryImport attribute
LibraryImportCompilationData libraryImportData =
ProcessLibraryImportAttribute(generatedDllImportAttr!) ??
new LibraryImportCompilationData("INVALID_CSHARP_SYNTAX");
if (lcidConversionAttr is not null)
{
// Using LCIDConversion with LibraryImport is not supported
generatorDiagnostics.ReportConfigurationNotSupported(lcidConversionAttr, nameof(TypeNames.LCIDConversionAttribute));
}
// Create the stub.
var signatureContext = SignatureContext.Create(
symbol,
DownlevelLibraryImportGeneratorHelpers.CreateMarshallingInfoParser(environment, generatorDiagnostics, symbol, libraryImportData),
environment,
new CodeEmitOptions(SkipInit: false),
typeof(DownlevelLibraryImportGenerator).Assembly);
var containingTypeContext = new ContainingSyntaxContext(originalSyntax);
var methodSyntaxTemplate = new ContainingSyntax(originalSyntax.Modifiers, SyntaxKind.MethodDeclaration, originalSyntax.Identifier, originalSyntax.TypeParameterList);
List<AttributeSyntax> additionalAttributes = GenerateSyntaxForForwardedAttributes(defaultDllImportSearchPathsAttribute);
return new IncrementalStubGenerationContext(
signatureContext,
containingTypeContext,
methodSyntaxTemplate,
locations,
new SequenceEqualImmutableArray<AttributeSyntax>(additionalAttributes.ToImmutableArray(), SyntaxEquivalentComparer.Instance),
LibraryImportData.From(libraryImportData),
environment.EnvironmentFlags,
new SequenceEqualImmutableArray<DiagnosticInfo>(generatorDiagnostics.Diagnostics.ToImmutableArray())
);
}
private static (MemberDeclarationSyntax, ImmutableArray<DiagnosticInfo>) GenerateSource(
IncrementalStubGenerationContext pinvokeStub)
{
var diagnostics = new GeneratorDiagnosticsBag(new DiagnosticDescriptorProvider(), pinvokeStub.DiagnosticLocation, SR.ResourceManager, typeof(FxResources.Microsoft.Interop.LibraryImportGenerator.Downlevel.SR));
// Generate stub code
var stubGenerator = new ManagedToNativeStubGenerator(
pinvokeStub.SignatureContext.ElementTypeInformation,
pinvokeStub.LibraryImportData.SetLastError,
diagnostics,
DownlevelLibraryImportGeneratorHelpers.GeneratorResolver,
new CodeEmitOptions(SkipInit: false));
// Check if the generator should produce a forwarder stub - regular DllImport.
// This is done if the signature is blittable or if some parameters cannot be marshalled.
if (stubGenerator.NoMarshallingRequired
|| stubGenerator.HasForwardedTypes
|| pinvokeStub.LibraryImportData.SetLastError)
{
return (PrintForwarderStub(pinvokeStub.StubMethodSyntaxTemplate, pinvokeStub, diagnostics), pinvokeStub.Diagnostics.Array.AddRange(diagnostics.Diagnostics));
}
ImmutableArray<AttributeSyntax> forwardedAttributes = pinvokeStub.ForwardedAttributes.Array;
const string innerPInvokeName = "__PInvoke";
BlockSyntax code = stubGenerator.GenerateStubBody(innerPInvokeName);
LocalFunctionStatementSyntax dllImport = CreateTargetDllImportAsLocalStatement(
stubGenerator,
pinvokeStub.LibraryImportData,
innerPInvokeName,
pinvokeStub.StubMethodSyntaxTemplate.Identifier.Text);
if (!forwardedAttributes.IsEmpty)
{
dllImport = dllImport.AddAttributeLists(AttributeList(SeparatedList(forwardedAttributes)));
}
dllImport = dllImport.WithLeadingTrivia(Comment("// Local P/Invoke"));
code = code.AddStatements(dllImport);
return (pinvokeStub.ContainingSyntaxContext.WrapMemberInContainingSyntaxWithUnsafeModifier(PrintGeneratedSource(pinvokeStub.StubMethodSyntaxTemplate, pinvokeStub.SignatureContext, code)), pinvokeStub.Diagnostics.Array.AddRange(diagnostics.Diagnostics));
}
private static MemberDeclarationSyntax PrintForwarderStub(ContainingSyntax userDeclaredMethod, IncrementalStubGenerationContext stub, GeneratorDiagnosticsBag diagnostics)
{
LibraryImportData pinvokeData = stub.LibraryImportData with { EntryPoint = stub.LibraryImportData.EntryPoint ?? userDeclaredMethod.Identifier.ValueText };
if (pinvokeData.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshalling)
&& pinvokeData.StringMarshalling != StringMarshalling.Utf16)
{
// Report a diagnostic when a StringMarshalling other than Utf16 is used.
// The other options can't be forwarded for downlevel scenarios.
diagnostics.ReportCannotForwardToDllImport(
stub.DiagnosticLocation,
$"{nameof(TypeNames.LibraryImportAttribute)}{Type.Delimiter}{nameof(StringMarshalling)}",
$"{nameof(StringMarshalling)}{Type.Delimiter}{pinvokeData.StringMarshalling}");
pinvokeData = pinvokeData with { IsUserDefined = pinvokeData.IsUserDefined & ~InteropAttributeMember.StringMarshalling };
}
SyntaxTokenList modifiers = StripTriviaFromModifiers(userDeclaredMethod.Modifiers);
modifiers = modifiers.AddToModifiers(SyntaxKind.ExternKeyword);
// Create stub function
MethodDeclarationSyntax stubMethod = MethodDeclaration(stub.SignatureContext.StubReturnType, userDeclaredMethod.Identifier)
.WithModifiers(modifiers)
.WithParameterList(ParameterList(SeparatedList(stub.SignatureContext.StubParameters)))
.WithSemicolonToken(Token(SyntaxKind.SemicolonToken))
.AddModifiers()
.AddAttributeLists(
AttributeList(
SingletonSeparatedList(
CreateForwarderDllImport(pinvokeData))));
MemberDeclarationSyntax toPrint = stub.ContainingSyntaxContext.WrapMemberInContainingSyntaxWithUnsafeModifier(stubMethod);
return toPrint;
}
private static LocalFunctionStatementSyntax CreateTargetDllImportAsLocalStatement(
ManagedToNativeStubGenerator stubGenerator,
LibraryImportData libraryImportData,
string stubTargetName,
string stubMethodName)
{
(ParameterListSyntax parameterList, TypeSyntax returnType, AttributeListSyntax returnTypeAttributes) = stubGenerator.GenerateTargetMethodSignatureData();
LocalFunctionStatementSyntax localDllImport = LocalFunctionStatement(returnType, stubTargetName)
.AddModifiers(
Token(SyntaxKind.StaticKeyword),
Token(SyntaxKind.ExternKeyword),
Token(SyntaxKind.UnsafeKeyword))
.WithSemicolonToken(Token(SyntaxKind.SemicolonToken))
.WithAttributeLists(
SingletonList(AttributeList(
SingletonSeparatedList(
Attribute(
NameSyntaxes.DllImportAttribute,
AttributeArgumentList(
SeparatedList(
[
AttributeArgument(LiteralExpression(
SyntaxKind.StringLiteralExpression,
Literal(libraryImportData.ModuleName))),
AttributeArgument(
NameEquals(nameof(DllImportAttribute.EntryPoint)),
null,
LiteralExpression(
SyntaxKind.StringLiteralExpression,
Literal(libraryImportData.EntryPoint ?? stubMethodName))),
AttributeArgument(
NameEquals(nameof(DllImportAttribute.ExactSpelling)),
null,
LiteralExpression(SyntaxKind.TrueLiteralExpression))
]
)))))))
.WithParameterList(parameterList);
if (returnTypeAttributes is not null)
{
localDllImport = localDllImport.AddAttributeLists(returnTypeAttributes.WithTarget(AttributeTargetSpecifier(Token(SyntaxKind.ReturnKeyword))));
}
return localDllImport;
}
private static AttributeSyntax CreateForwarderDllImport(LibraryImportData target)
{
var newAttributeArgs = new List<AttributeArgumentSyntax>
{
AttributeArgument(LiteralExpression(
SyntaxKind.StringLiteralExpression,
Literal(target.ModuleName))),
AttributeArgument(
NameEquals(nameof(DllImportAttribute.EntryPoint)),
null,
CreateStringExpressionSyntax(target.EntryPoint)),
AttributeArgument(
NameEquals(nameof(DllImportAttribute.ExactSpelling)),
null,
LiteralExpression(SyntaxKind.TrueLiteralExpression))
};
if (target.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshalling))
{
Debug.Assert(target.StringMarshalling == StringMarshalling.Utf16);
NameEqualsSyntax name = NameEquals(nameof(DllImportAttribute.CharSet));
ExpressionSyntax value = MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
ParseTypeName(typeof(CharSet).FullName),
IdentifierName(nameof(CharSet.Unicode)));
newAttributeArgs.Add(AttributeArgument(name, null, value));
}
if (target.IsUserDefined.HasFlag(InteropAttributeMember.SetLastError))
{
NameEqualsSyntax name = NameEquals(nameof(DllImportAttribute.SetLastError));
ExpressionSyntax value = CreateBoolExpressionSyntax(target.SetLastError);
newAttributeArgs.Add(AttributeArgument(name, null, value));
}
// Create new attribute
return Attribute(
NameSyntaxes.DllImportAttribute,
AttributeArgumentList(SeparatedList(newAttributeArgs)));
static ExpressionSyntax CreateBoolExpressionSyntax(bool trueOrFalse)
{
return LiteralExpression(
trueOrFalse
? SyntaxKind.TrueLiteralExpression
: SyntaxKind.FalseLiteralExpression);
}
static ExpressionSyntax CreateStringExpressionSyntax(string str)
{
return LiteralExpression(
SyntaxKind.StringLiteralExpression,
Literal(str));
}
}
private static DiagnosticInfo? GetDiagnosticIfInvalidMethodForGeneration(MethodDeclarationSyntax methodSyntax, IMethodSymbol method)
{
// Verify the method has no generic types or defined implementation
// and is marked static and partial.
if (methodSyntax.TypeParameterList is not null
|| methodSyntax.Body is not null
|| !methodSyntax.Modifiers.Any(SyntaxKind.StaticKeyword)
|| !methodSyntax.Modifiers.Any(SyntaxKind.PartialKeyword))
{
return DiagnosticInfo.Create(GeneratorDiagnostics.InvalidAttributedMethodSignature, methodSyntax.Identifier.GetLocation(), method.Name);
}
// Verify that the types the method is declared in are marked partial.
if (methodSyntax.Parent is TypeDeclarationSyntax typeDecl && !typeDecl.IsInPartialContext(out var nonPartialIdentifier))
{
return DiagnosticInfo.Create(GeneratorDiagnostics.InvalidAttributedMethodContainingTypeMissingModifiers, methodSyntax.Identifier.GetLocation(), method.Name, nonPartialIdentifier);
}
// Verify the method does not have a ref return
if (method.ReturnsByRef || method.ReturnsByRefReadonly)
{
return DiagnosticInfo.Create(GeneratorDiagnostics.ReturnConfigurationNotSupported, methodSyntax.Identifier.GetLocation(), "ref return", method.ToDisplayString());
}
return null;
}
}
}
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