[modules] If we load two declarations with typedef names for linkage purposes

on top of a local declaration of the same entity, we still need to remember
that we loaded the first one or we may fail to merge the second one properly.

llvm-svn: 226765

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -2554,15 +2554,21 @@ static DeclContext *getPrimaryContextForMerging(DeclContext *DC) {
 }
 
 ASTDeclReader::FindExistingResult::~FindExistingResult() {
+  // Record that we had a typedef name for linkage whether or not we merge
+  // with that declaration.
+  if (TypedefNameForLinkage) {
+    DeclContext *DC = New->getDeclContext()->getRedeclContext();
+    Reader.ImportedTypedefNamesForLinkage.insert(
+        std::make_pair(std::make_pair(DC, TypedefNameForLinkage), New));
+    return;
+  }
+
   if (!AddResult || Existing)
     return;
 
   DeclarationName Name = New->getDeclName();
   DeclContext *DC = New->getDeclContext()->getRedeclContext();
-  if (TypedefNameForLinkage) {
-    Reader.ImportedTypedefNamesForLinkage.insert(
-        std::make_pair(std::make_pair(DC, TypedefNameForLinkage), New));
-  } else if (!Name) {
+  if (!Name) {
     assert(needsAnonymousDeclarationNumber(New));
     setAnonymousDeclForMerging(Reader, New->getLexicalDeclContext(),
                                AnonymousDeclNumber, New);

clang/test/Modules/Inputs/merge-name-for-linkage/a.h

@@ -0,0 +1 @@
+typedef union {} pthread_mutex_t;

clang/test/Modules/Inputs/merge-name-for-linkage/b.h

@@ -0,0 +1 @@
+typedef union {} pthread_mutex_t;

clang/test/Modules/Inputs/merge-name-for-linkage/module.modulemap

@@ -0,0 +1,2 @@
+module a { header "a.h" export * }
+module b { header "b.h" export * }

clang/test/Modules/merge-name-for-linkage.cc

@@ -0,0 +1,8 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -I%S/Inputs/merge-name-for-linkage -verify %s
+// expected-no-diagnostics
+typedef union {} pthread_mutex_t;
+#include "a.h"
+pthread_mutex_t x;
+#include "b.h"
+pthread_mutex_t y;