MS ABI: Treat explicit instantiation definitions of dllimport function templates as explicit instantiation decls (PR35435)

This matches MSVC's behaviour, and we already do it for class templates
since r270897.

Differential revision: https://reviews.llvm.org/D40621

llvm-svn: 319386

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 26b80f11fb4..e110a8cc814 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -9239,10 +9239,18 @@ DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
       return (Decl*) nullptr;
   }
 
-  Specialization->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
   if (Attr)
     ProcessDeclAttributeList(S, Specialization, Attr);
 
+  // In MSVC mode, dllimported explicit instantiation definitions are treated as
+  // instantiation declarations.
+  if (TSK == TSK_ExplicitInstantiationDefinition &&
+      Specialization->hasAttr<DLLImportAttr>() &&
+      Context.getTargetInfo().getCXXABI().isMicrosoft())
+    TSK = TSK_ExplicitInstantiationDeclaration;
+
+  Specialization->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
+
   if (Specialization->isDefined()) {
     // Let the ASTConsumer know that this function has been explicitly
     // instantiated now, and its linkage might have changed.