void MakeOutputTypeInference(ResolveResult e, IType t)
{
Log.WriteLine(" MakeOutputTypeInference from " + e + " to " + t);
// If E is an anonymous function with inferred return type U (§7.5.2.12) and T is a delegate type or expression
// tree type with return type Tb, then a lower-bound inference (§7.5.2.9) is made from U to Tb.
LambdaResolveResult lrr = e as LambdaResolveResult;
if (lrr != null)
{
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m != null)
{
IType inferredReturnType;
if (lrr.IsImplicitlyTyped)
{
if (m.Parameters.Count != lrr.Parameters.Count)
{
return; // cannot infer due to mismatched parameter lists
}
TypeParameterSubstitution substitution = GetSubstitutionForFixedTPs();
IType[] inferredParameterTypes = new IType[m.Parameters.Count];
for (int i = 0; i < inferredParameterTypes.Length; i++)
{
IType parameterType = m.Parameters[i].Type;
inferredParameterTypes[i] = parameterType.AcceptVisitor(substitution);
}
inferredReturnType = lrr.GetInferredReturnType(inferredParameterTypes);
}
else
{
inferredReturnType = lrr.GetInferredReturnType(null);
}
MakeLowerBoundInference(inferredReturnType, m.ReturnType);
return;
}
}
// Otherwise, if E is a method group and T is a delegate type or expression tree type
// with parameter types T1…Tk and return type Tb, and overload resolution
// of E with the types T1…Tk yields a single method with return type U, then a lower-bound
// inference is made from U to Tb.
MethodGroupResolveResult mgrr = e as MethodGroupResolveResult;
if (mgrr != null)
{
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m != null)
{
ResolveResult[] args = new ResolveResult[m.Parameters.Count];
TypeParameterSubstitution substitution = GetSubstitutionForFixedTPs();
for (int i = 0; i < args.Length; i++)
{
IParameter param = m.Parameters[i];
IType parameterType = param.Type.AcceptVisitor(substitution);
if ((param.IsRef || param.IsOut) && parameterType.Kind == TypeKind.ByReference)
{
parameterType = ((ByReferenceType)parameterType).ElementType;
args[i] = new ByReferenceResolveResult(parameterType, param.IsOut);
}
else
{
args[i] = new ResolveResult(parameterType);
}
}
var or = mgrr.PerformOverloadResolution(compilation,
args,
allowExpandingParams: false, allowOptionalParameters: false);
if (or.FoundApplicableCandidate && or.BestCandidateAmbiguousWith == null)
{
IType returnType = or.GetBestCandidateWithSubstitutedTypeArguments().ReturnType;
MakeLowerBoundInference(returnType, m.ReturnType);
}
}
return;
}
// Otherwise, if E is an expression with type U, then a lower-bound inference is made from U to T.
if (IsValidType(e.Type))
{
MakeLowerBoundInference(e.Type, t);
}
}
public static ResolveResult Resolve(Lazy <ICompilation> compilation, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree, TextLocation location, out AstNode node,
CancellationToken cancellationToken = default(CancellationToken))
{
node = syntaxTree.GetNodeAt(location);
if (node == null || node is ArrayInitializerExpression)
{
return(null);
}
if (node.Parent is UsingAliasDeclaration && node.Role == UsingAliasDeclaration.AliasRole)
{
var r = new CSharpAstResolver(compilation.Value, syntaxTree, unresolvedFile);
return(r.Resolve(((UsingAliasDeclaration)node.Parent).Import, cancellationToken));
}
if (CSharpAstResolver.IsUnresolvableNode(node))
{
if (node is Identifier)
{
node = node.Parent;
}
else if (node.NodeType == NodeType.Token)
{
if (node.Parent is IndexerExpression || node.Parent is ConstructorInitializer)
{
// There's no other place where one could hover to see the indexer's tooltip,
// so we need to resolve it when hovering over the '[' or ']'.
// For constructor initializer, the same applies to the 'base'/'this' token.
node = node.Parent;
}
else
{
return(null);
}
}
else
{
// don't resolve arbitrary nodes - we don't want to show tooltips for everything
return(null);
}
}
else
{
// It's a resolvable node.
// However, we usually don't want to show the tooltip everywhere
// For example, hovering with the mouse over an empty line between two methods causes
// node==TypeDeclaration, but we don't want to show any tooltip.
if (!node.GetChildByRole(Roles.Identifier).IsNull)
{
// We'll suppress the tooltip for resolvable nodes if there is an identifier that
// could be hovered over instead:
return(null);
}
}
if (node == null)
{
return(null);
}
if (node.Parent is ObjectCreateExpression && node.Role == Roles.Type)
{
node = node.Parent;
}
InvocationExpression parentInvocation = null;
if ((node is IdentifierExpression || node is MemberReferenceExpression || node is PointerReferenceExpression) && node.Role != Roles.Argument)
{
// we also need to resolve the invocation
parentInvocation = node.Parent as InvocationExpression;
}
// TODO: I think we should provide an overload so that an existing CSharpAstResolver can be reused
CSharpAstResolver resolver = new CSharpAstResolver(compilation.Value, syntaxTree, unresolvedFile);
ResolveResult rr = resolver.Resolve(node, cancellationToken);
MethodGroupResolveResult mgrr = rr as MethodGroupResolveResult;
if (mgrr != null)
{
// For method groups, resolve the parent invocation instead.
if (parentInvocation != null)
{
return(resolver.Resolve(parentInvocation));
}
if (node is Expression)
{
// If it's not an invocation, try if it's a conversion to a delegate type:
Conversion c = resolver.GetConversion((Expression)node, cancellationToken);
if (c.IsMethodGroupConversion)
{
return(new MemberResolveResult(mgrr.TargetResult, c.Method));
}
}
}
return(rr);
}
