/// <summary>
/// If the extension method is applicable based on the "this" argument type, return
/// the method constructed with the inferred type arguments. If the method is not an
/// unconstructed generic method, type inference is skipped. If the method is not
/// applicable, or if constraints when inferring type parameters from the "this" type
/// are not satisfied, the return value is null.
/// </summary>
public static MethodSymbol InferExtensionMethodTypeArguments(this MethodSymbol method, TypeSymbol thisType, Compilation compilation, ref HashSet <DiagnosticInfo> useSiteDiagnostics)
{
Debug.Assert(method.IsExtensionMethod);
Debug.Assert((object)thisType != null);
if (!method.IsGenericMethod || method != method.ConstructedFrom)
{
return(method);
}
// We never resolve extension methods on a dynamic receiver.
if (thisType.IsDynamic())
{
return(null);
}
var containingAssembly = method.ContainingAssembly;
var errorNamespace = containingAssembly.GlobalNamespace;
var conversions = new TypeConversions(containingAssembly.CorLibrary);
// There is absolutely no plausible syntax/tree that we could use for these
// synthesized literals. We could be speculatively binding a call to a PE method.
var syntaxTree = CSharpSyntaxTree.Dummy;
var syntax = (CSharpSyntaxNode)syntaxTree.GetRoot();
// Create an argument value for the "this" argument of specific type,
// and pass the same bad argument value for all other arguments.
var thisArgumentValue = new BoundLiteral(syntax, ConstantValue.Bad, thisType)
{
WasCompilerGenerated = true
};
var otherArgumentType = new ExtendedErrorTypeSymbol(errorNamespace, name: string.Empty, arity: 0, errorInfo: null, unreported: false);
var otherArgumentValue = new BoundLiteral(syntax, ConstantValue.Bad, otherArgumentType)
{
WasCompilerGenerated = true
};
var paramCount = method.ParameterCount;
var arguments = new BoundExpression[paramCount];
var argumentTypes = new TypeSymbol[paramCount];
for (int i = 0; i < paramCount; i++)
{
var argument = (i == 0) ? thisArgumentValue : otherArgumentValue;
arguments[i] = argument;
argumentTypes[i] = argument.Type;
}
var typeArgs = MethodTypeInferrer.InferTypeArgumentsFromFirstArgument(
conversions,
method,
argumentTypes.AsImmutableOrNull(),
arguments.AsImmutableOrNull(),
ref useSiteDiagnostics);
if (typeArgs.IsDefault)
{
return(null);
}
// Check constraints.
var diagnosticsBuilder = ArrayBuilder <TypeParameterDiagnosticInfo> .GetInstance();
var typeParams = method.TypeParameters;
var substitution = new TypeMap(typeParams, typeArgs);
ArrayBuilder <TypeParameterDiagnosticInfo> useSiteDiagnosticsBuilder = null;
var success = method.CheckConstraints(conversions, substitution, method.TypeParameters, typeArgs, compilation, diagnosticsBuilder, ref useSiteDiagnosticsBuilder);
diagnosticsBuilder.Free();
if (useSiteDiagnosticsBuilder != null && useSiteDiagnosticsBuilder.Count > 0)
{
if (useSiteDiagnostics == null)
{
useSiteDiagnostics = new HashSet <DiagnosticInfo>();
}
foreach (var diag in useSiteDiagnosticsBuilder)
{
useSiteDiagnostics.Add(diag.DiagnosticInfo);
}
}
if (!success)
{
return(null);
}
return(method.Construct(typeArgs));
}
private static MethodSymbol InferExtensionMethodTypeArguments(MethodSymbol method, TypeSymbol thisType, CSharpCompilation compilation, ref HashSet <DiagnosticInfo> useSiteDiagnostics)
{
Debug.Assert(method.IsExtensionMethod);
Debug.Assert((object)thisType != null);
if (!method.IsGenericMethod || method != method.ConstructedFrom)
{
return(method);
}
// We never resolve extension methods on a dynamic receiver.
if (thisType.IsDynamic())
{
return(null);
}
var containingAssembly = method.ContainingAssembly;
var errorNamespace = containingAssembly.GlobalNamespace;
var conversions = new TypeConversions(containingAssembly.CorLibrary);
// There is absolutely no plausible syntax/tree that we could use for these
// synthesized literals. We could be speculatively binding a call to a PE method.
var syntaxTree = CSharpSyntaxTree.Dummy;
var syntax = (CSharpSyntaxNode)syntaxTree.GetRoot();
// Create an argument value for the "this" argument of specific type,
// and pass the same bad argument value for all other arguments.
var thisArgumentValue = new BoundLiteral(syntax, ConstantValue.Bad, thisType)
{
WasCompilerGenerated = true
};
var otherArgumentType = new ExtendedErrorTypeSymbol(errorNamespace, name: string.Empty, arity: 0, errorInfo: null, unreported: false);
var otherArgumentValue = new BoundLiteral(syntax, ConstantValue.Bad, otherArgumentType)
{
WasCompilerGenerated = true
};
var paramCount = method.ParameterCount;
var arguments = new BoundExpression[paramCount];
for (int i = 0; i < paramCount; i++)
{
var argument = (i == 0) ? thisArgumentValue : otherArgumentValue;
arguments[i] = argument;
}
var typeArgs = MethodTypeInferrer.InferTypeArgumentsFromFirstArgument(
conversions,
method,
arguments.AsImmutable(),
useSiteDiagnostics: ref useSiteDiagnostics);
if (typeArgs.IsDefault)
{
return(null);
}
// For the purpose of constraint checks we use error type symbol in place of type arguments that we couldn't infer from the first argument.
// This prevents constraint checking from failing for corresponding type parameters.
int firstNullInTypeArgs = -1;
var notInferredTypeParameters = PooledHashSet <TypeParameterSymbol> .GetInstance();
var typeParams = method.TypeParameters;
var typeArgsForConstraintsCheck = typeArgs;
for (int i = 0; i < typeArgsForConstraintsCheck.Length; i++)
{
if (!typeArgsForConstraintsCheck[i].HasType)
{
firstNullInTypeArgs = i;
var builder = ArrayBuilder <TypeWithAnnotations> .GetInstance();
builder.AddRange(typeArgsForConstraintsCheck, firstNullInTypeArgs);
for (; i < typeArgsForConstraintsCheck.Length; i++)
{
var typeArg = typeArgsForConstraintsCheck[i];
if (!typeArg.HasType)
{
notInferredTypeParameters.Add(typeParams[i]);
builder.Add(TypeWithAnnotations.Create(ErrorTypeSymbol.UnknownResultType));
}
else
{
builder.Add(typeArg);
}
}
typeArgsForConstraintsCheck = builder.ToImmutableAndFree();
break;
}
}
// Check constraints.
var diagnosticsBuilder = ArrayBuilder <TypeParameterDiagnosticInfo> .GetInstance();
var substitution = new TypeMap(typeParams, typeArgsForConstraintsCheck);
ArrayBuilder <TypeParameterDiagnosticInfo> useSiteDiagnosticsBuilder = null;
var success = method.CheckConstraints(conversions, substitution, typeParams, typeArgsForConstraintsCheck, compilation, diagnosticsBuilder, nullabilityDiagnosticsBuilderOpt: null, ref useSiteDiagnosticsBuilder,
ignoreTypeConstraintsDependentOnTypeParametersOpt: notInferredTypeParameters.Count > 0 ? notInferredTypeParameters : null);
diagnosticsBuilder.Free();
notInferredTypeParameters.Free();
if (useSiteDiagnosticsBuilder != null && useSiteDiagnosticsBuilder.Count > 0)
{
if (useSiteDiagnostics == null)
{
useSiteDiagnostics = new HashSet <DiagnosticInfo>();
}
foreach (var diag in useSiteDiagnosticsBuilder)
{
useSiteDiagnostics.Add(diag.DiagnosticInfo);
}
}
if (!success)
{
return(null);
}
// For the purpose of construction we use original type parameters in place of type arguments that we couldn't infer from the first argument.
ImmutableArray <TypeWithAnnotations> typeArgsForConstruct = typeArgs;
if (typeArgs.Any(t => !t.HasType))
{
typeArgsForConstruct = typeArgs.ZipAsArray(
method.TypeParameters,
(t, tp) => t.HasType ? t : TypeWithAnnotations.Create(tp));
}
return(method.Construct(typeArgsForConstruct));
}
/// <summary>
/// If the extension method is applicable based on the "this" argument type, return
/// the method constructed with the inferred type arguments. If the method is not an
/// unconstructed generic method, type inference is skipped. If the method is not
/// applicable, or if constraints when inferring type parameters from the "this" type
/// are not satisfied, the return value is null.
/// </summary>
private static MethodSymbol InferExtensionMethodTypeArguments(MethodSymbol method, TypeSymbol thisType, ref HashSet <DiagnosticInfo> useSiteDiagnostics)
{
Debug.Assert(method.IsExtensionMethod);
Debug.Assert((object)thisType != null);
if (!method.IsGenericMethod || method != method.ConstructedFrom)
{
return(method);
}
// We never resolve extension methods on a dynamic receiver.
if (thisType.IsDynamic())
{
return(null);
}
var containingAssembly = method.ContainingAssembly;
var errorNamespace = containingAssembly.GlobalNamespace;
var conversions = new TypeConversions(containingAssembly.CorLibrary);
// There is absolutely no plausible syntax/tree that we could use for these
// synthesized literals. We could be speculatively binding a call to a PE method.
var syntaxTree = CSharpSyntaxTree.Dummy;
var syntax = (CSharpSyntaxNode)syntaxTree.GetRoot();
// Create an argument value for the "this" argument of specific type,
// and pass the same bad argument value for all other arguments.
var thisArgumentValue = new BoundLiteral(syntax, ConstantValue.Bad, thisType)
{
WasCompilerGenerated = true
};
var otherArgumentType = new ExtendedErrorTypeSymbol(errorNamespace, name: string.Empty, arity: 0, errorInfo: null, unreported: false);
var otherArgumentValue = new BoundLiteral(syntax, ConstantValue.Bad, otherArgumentType)
{
WasCompilerGenerated = true
};
var paramCount = method.ParameterCount;
var arguments = new BoundExpression[paramCount];
for (int i = 0; i < paramCount; i++)
{
var argument = (i == 0) ? thisArgumentValue : otherArgumentValue;
arguments[i] = argument;
}
var typeArgs = MethodTypeInferrer.InferTypeArgumentsFromFirstArgument(
conversions,
method,
arguments.AsImmutable(),
useSiteDiagnostics: ref useSiteDiagnostics);
if (typeArgs.IsDefault)
{
return(null);
}
// For the purpose of construction we use original type parameters in place of type arguments that we couldn't infer from the first argument.
ImmutableArray <TypeWithAnnotations> typeArgsForConstruct = typeArgs;
if (typeArgs.Any(t => !t.HasType))
{
typeArgsForConstruct = typeArgs.ZipAsArray(
method.TypeParameters,
(t, tp) => t.HasType ? t : TypeWithAnnotations.Create(tp));
}
return(method.Construct(typeArgsForConstruct));
}