From c0fbba7d8a6e03f43f18373b95a96cd107d3b392 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Wed, 3 Apr 2013 22:49:41 +0000
Subject: [PATCH] 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        | 6 +++++-
 clang/lib/Serialization/ASTReader.cpp     | 8 +++++++-
 clang/lib/Serialization/ASTReaderDecl.cpp | 4 ----
 clang/lib/Serialization/ASTWriter.cpp     | 2 --
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
index 852bb9ab0400..4af49efb7d55 100644
--- a/clang/include/clang/AST/DeclBase.h
+++ b/clang/include/clang/AST/DeclBase.h
@@ -1479,7 +1479,11 @@ public:
   inline ddiag_iterator ddiag_end() const;
 
   // 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.
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 4c4277c30fd0..d9844152b740 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/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;
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 3dcae6fe6a34..0fbdd7e5daeb 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/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());
 
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 6893b5003ffb..cf93d1cf01a7 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/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;