Fix tracking of merged definitions when the merge target is also merged
into something else.

llvm-svn: 342017
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index ab2a95e..0ed52ff 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -933,13 +933,13 @@
       Listener->RedefinedHiddenDefinition(ND, M);
 
   if (getLangOpts().ModulesLocalVisibility)
-    MergedDefModules[ND].push_back(M);
+    MergedDefModules[cast<NamedDecl>(ND->getCanonicalDecl())].push_back(M);
   else
     ND->setVisibleDespiteOwningModule();
 }
 
 void ASTContext::deduplicateMergedDefinitonsFor(NamedDecl *ND) {
-  auto It = MergedDefModules.find(ND);
+  auto It = MergedDefModules.find(cast<NamedDecl>(ND->getCanonicalDecl()));
   if (It == MergedDefModules.end())
     return;