Ignore calling conventions when checking function template specializations

Summary:
Calling conventions are inherited during decl merging.  Before this
change, deduction would fail due to a type mismatch between the template
and the specialization.  This change adjusts the CCs to match before
deduction, and lets the decl merging logic diagnose mismatch or inherit
the CC from the template.

This allows specializations of static member function templates in the
Microsoft C++ ABI.

Reviewers: rsmith

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1570

llvm-svn: 190377

1 files changed, 13 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 015d9d8ce94..b6313307c42 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -6403,11 +6403,11 @@ bool Sema::CheckFunctionTemplateSpecialization(
       // it will be a static member function until we know which template it
       // specializes), so adjust it now assuming it specializes this template.
       QualType FT = FD->getType();
+      const FunctionProtoType *FPT = FT->castAs<FunctionProtoType>();
+      FunctionDecl *TmplFD = FunTmpl->getTemplatedDecl();
       if (FD->isConstexpr()) {
-        CXXMethodDecl *OldMD =
-          dyn_cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl());
+        CXXMethodDecl *OldMD = dyn_cast<CXXMethodDecl>(TmplFD);
         if (OldMD && OldMD->isConst()) {
-          const FunctionProtoType *FPT = FT->castAs<FunctionProtoType>();
           FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
           EPI.TypeQuals |= Qualifiers::Const;
           FT = Context.getFunctionType(FPT->getResultType(), FPT->getArgTypes(),
@@ -6415,6 +6415,16 @@ bool Sema::CheckFunctionTemplateSpecialization(
         }
       }
 
+      // Ignore differences in calling convention until decl merging.
+      const FunctionProtoType *TmplFT =
+          TmplFD->getType()->castAs<FunctionProtoType>();
+      if (FPT->getCallConv() != TmplFT->getCallConv()) {
+        FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
+        EPI.ExtInfo = EPI.ExtInfo.withCallingConv(TmplFT->getCallConv());
+        FT = Context.getFunctionType(FPT->getResultType(), FPT->getArgTypes(),
+                                     EPI);
+      }
+
       // C++ [temp.expl.spec]p11:
       //   A trailing template-argument can be left unspecified in the
       //   template-id naming an explicit function template specialization