[modules] Properly look up the owning module for an instantiation of a merged template.

When looking for the template instantiation pattern of a templated entity,
consistently select the definition of the pattern if there is one. This means
we'll pick the same owning module when we start instantiating a template that
we'll later pick when determining which modules are visible during that
instantiation.

llvm-svn: 300650

1 files changed, 5 insertions, 17 deletions

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index e4d420f3683..0ac3eebcf29 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1326,12 +1326,6 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
   return !R.empty();
 }
 
-/// \brief Find the declaration that a class temploid member specialization was
-/// instantiated from, or the member itself if it is an explicit specialization.
-static Decl *getInstantiatedFrom(Decl *D, MemberSpecializationInfo *MSInfo) {
-  return MSInfo->isExplicitSpecialization() ? D : MSInfo->getInstantiatedFrom();
-}
-
 Module *Sema::getOwningModule(Decl *Entity) {
   // If it's imported, grab its owning module.
   Module *M = Entity->getImportedOwningModule();
@@ -1413,20 +1407,14 @@ static Module *getDefiningModule(Sema &S, Decl *Entity) {
     if (CXXRecordDecl *Pattern = RD->getTemplateInstantiationPattern())
       Entity = Pattern;
   } else if (EnumDecl *ED = dyn_cast<EnumDecl>(Entity)) {
-    if (MemberSpecializationInfo *MSInfo = ED->getMemberSpecializationInfo())
-      Entity = getInstantiatedFrom(ED, MSInfo);
+    if (auto *Pattern = ED->getTemplateInstantiationPattern())
+      Entity = Pattern;
   } else if (VarDecl *VD = dyn_cast<VarDecl>(Entity)) {
-    // FIXME: Map from variable template specializations back to the template.
-    if (MemberSpecializationInfo *MSInfo = VD->getMemberSpecializationInfo())
-      Entity = getInstantiatedFrom(VD, MSInfo);
+    if (VarDecl *Pattern = VD->getTemplateInstantiationPattern())
+      Entity = Pattern;
   }
 
-  // Walk up to the containing context. That might also have been instantiated
-  // from a template.
-  DeclContext *Context = Entity->getDeclContext();
-  if (Context->isFileContext())
-    return S.getOwningModule(Entity);
-  return getDefiningModule(S, cast<Decl>(Context));
+  return S.getOwningModule(Entity);
 }
 
 llvm::DenseSet<Module*> &Sema::getLookupModules() {