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.

llvm-svn: 93162

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 8965199c2f7..41f0886e764 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -2743,7 +2743,9 @@ Sema::DeclPtrTy Sema::ActOnConversionDeclarator(CXXConversionDecl *Conversion) {
       << ClassType << ConvType;
   }
 
-  if (Conversion->getPreviousDeclaration()) {
+  if (Conversion->getPrimaryTemplate()) {
+    // ignore specializations
+  } else if (Conversion->getPreviousDeclaration()) {
     const NamedDecl *ExpectedPrevDecl = Conversion->getPreviousDeclaration();
     if (FunctionTemplateDecl *ConversionTemplate
           = Conversion->getDescribedFunctionTemplate())
@@ -2754,7 +2756,7 @@ Sema::DeclPtrTy Sema::ActOnConversionDeclarator(CXXConversionDecl *Conversion) {
   } else if (FunctionTemplateDecl *ConversionTemplate
                = Conversion->getDescribedFunctionTemplate())
     ClassDecl->addConversionFunction(ConversionTemplate);
-  else if (!Conversion->getPrimaryTemplate()) // ignore specializations
+  else 
     ClassDecl->addConversionFunction(Conversion);
 
   return DeclPtrTy::make(Conversion);