Pare back r164351 somewhat. The problem that change was addressing was that we
don't serialize a lookup map for the translation unit outside C++ mode, so we
can't tell when lookup within the TU needs to look within modules. Only apply
the fix outside C++ mode, and only to the translation unit.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178706 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 4c4277c..d984415 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -1995,8 +1995,14 @@
       Error("error at end of module block in AST file");
       return true;
     case llvm::BitstreamEntry::EndBlock: {
+      // Outside of C++, we do not store a lookup map for the translation unit.
+      // Instead, mark it as needing a lookup map to be built if this module
+      // contains any declarations lexically within it (which it always does!).
+      // This usually has no cost, since we very rarely need the lookup map for
+      // the translation unit outside C++.
       DeclContext *DC = Context.getTranslationUnitDecl();
-      if (!DC->hasExternalVisibleStorage() && DC->hasExternalLexicalStorage())
+      if (DC->hasExternalLexicalStorage() &&
+          !getContext().getLangOpts().CPlusPlus)
         DC->setMustBuildLookupTable();
       
       return false;
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 3dcae6f..0fbdd7e 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -2196,10 +2196,6 @@
       }
       PendingVisibleUpdates.erase(I);
     }
-
-    if (!LookupDC->hasExternalVisibleStorage() &&
-        DC->hasExternalLexicalStorage())
-      LookupDC->setMustBuildLookupTable();
   }
   assert(Idx == Record.size());
 
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 6893b50..cf93d1c 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -3324,8 +3324,6 @@
 
   // If not in C++, we perform name lookup for the translation unit via the
   // IdentifierInfo chains, don't bother to build a visible-declarations table.
-  // FIXME: In C++ we need the visible declarations in order to "see" the
-  // friend declarations, is there a way to do this without writing the table ?
   if (DC->isTranslationUnit() && !Context.getLangOpts().CPlusPlus)
     return 0;