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.

llvm-svn: 178706

clang/include/clang/AST/DeclBase.h

@@ -1480,6 +1480,10 @@ public:
 
   // Low-level accessors
 
+  bool mustBuildLookupTable() {
+    return LookupPtr.getInt();
+  }
+
   /// \brief Mark the lookup table as needing to be built.  This should be
   /// used only if setHasExternalLexicalStorage() has been called on any
   /// decl context for which this is the primary context.

clang/lib/Serialization/ASTReader.cpp

@@ -1995,8 +1995,14 @@ bool ASTReader::ReadASTBlock(ModuleFile &F) {
       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;

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -2196,10 +2196,6 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
       }
       PendingVisibleUpdates.erase(I);
     }
-
-    if (!LookupDC->hasExternalVisibleStorage() &&
-        DC->hasExternalLexicalStorage())
-      LookupDC->setMustBuildLookupTable();
   }
   assert(Idx == Record.size());
 

clang/lib/Serialization/ASTWriter.cpp

@@ -3324,8 +3324,6 @@ uint64_t ASTWriter::WriteDeclContextVisibleBlock(ASTContext &Context,
 
   // 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;