Implement name lookup for conversion function template specializations

(C++ [temp.mem]p5-6), which involves template argument deduction based
on the type named, e.g., given

  struct X { template<typename T> operator T*(); } x;

when we call

  x.operator int*();

we perform template argument deduction to determine that T=int. This
template argument deduction is needed for template specialization and
explicit instantiation, e.g.,

  template<> X::operator float*() { /* ... */ }

and when calling or otherwise naming a conversion function (as in the
first example). 

This fixes PR5742 and PR5762, although there's some remaining ugliness
that's causing out-of-line definitions of conversion function
templates to fail. I'll look into that separately.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@93162 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 4 deletions

diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 86ad0a0a73..499160d11f 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -897,12 +897,16 @@ QualType Sema::GetTypeForDeclarator(Declarator &D, Scope *S,
 
   case UnqualifiedId::IK_ConstructorName:
   case UnqualifiedId::IK_DestructorName:
-  case UnqualifiedId::IK_ConversionFunctionId:
     // Constructors and destructors don't have return types. Use
-    // "void" instead. Conversion operators will check their return
-    // types separately.
+    // "void" instead. 
     T = Context.VoidTy;
     break;
+
+  case UnqualifiedId::IK_ConversionFunctionId:
+    // The result type of a conversion function is the type that it
+    // converts to.
+    T = GetTypeFromParser(D.getName().ConversionFunctionId);
+    break;
   }
   
   if (T.isNull())
@@ -1041,7 +1045,8 @@ QualType Sema::GetTypeForDeclarator(Declarator &D, Scope *S,
       const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
 
       // C99 6.7.5.3p1: The return type may not be a function or array type.
-      if (T->isArrayType() || T->isFunctionType()) {
+      if ((T->isArrayType() || T->isFunctionType()) &&
+          (D.getName().getKind() != UnqualifiedId::IK_ConversionFunctionId)) {
         Diag(DeclType.Loc, diag::err_func_returning_array_function) << T;
         T = Context.IntTy;
         D.setInvalidType(true);