From cc9406c055e329dde1b1aeb610e449ae6981863a Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Mon, 8 Apr 2013 23:11:25 +0000
Subject: <rdar://problem/13540899> Collect using directives from all of the
 semantic contexts not represented by scopes.

This fixes a regression I introduced in r178136, where we would not
consider the using directives from the semantic declaration contexts
that aren't represented by the lexical scopes (Scope) when performing
unqualified name lookup. This lead to horribly funny diagnostics like
"no identifier named 'foo'; did you mean 'foo'?".

llvm-svn: 179067
---
 clang/lib/Sema/SemaLookup.cpp | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

(limited to 'clang/lib/Sema/SemaLookup.cpp')

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index df9fdeb40d6..ebe28944062 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -884,6 +884,8 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
   //   }
   // }
   //
+  UnqualUsingDirectiveSet UDirs;
+  bool VisitedUsingDirectives = false;
   DeclContext *OutsideOfTemplateParamDC = 0;
   for (; S && !isNamespaceOrTranslationUnitScope(S); S = S->getParent()) {
     DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity());
@@ -957,9 +959,24 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
         // If this is a file context, we need to perform unqualified name
         // lookup considering using directives.
         if (Ctx->isFileContext()) {
-          UnqualUsingDirectiveSet UDirs;
-          UDirs.visit(Ctx, Ctx);
-          UDirs.done();
+          // If we haven't handled using directives yet, do so now.
+          if (!VisitedUsingDirectives) {
+            // Add using directives from this context up to the top level.
+            for (DeclContext *UCtx = Ctx; UCtx; UCtx = UCtx->getParent())
+              UDirs.visit(UCtx, UCtx);
+
+            // Find the innermost file scope, so we can add using directives
+            // from local scopes.
+            Scope *InnermostFileScope = S;
+            while (InnermostFileScope &&
+                   !isNamespaceOrTranslationUnitScope(InnermostFileScope))
+              InnermostFileScope = InnermostFileScope->getParent();
+            UDirs.visitScopeChain(Initial, InnermostFileScope);
+
+            UDirs.done();
+
+            VisitedUsingDirectives = true;
+          }
 
           if (CppNamespaceLookup(*this, R, Context, Ctx, UDirs)) {
             R.resolveKind();
@@ -994,11 +1011,11 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
   //
   // FIXME: Cache this sorted list in Scope structure, and DeclContext, so we
   // don't build it for each lookup!
-
-  UnqualUsingDirectiveSet UDirs;
-  UDirs.visitScopeChain(Initial, S);
-  UDirs.done();
-
+  if (!VisitedUsingDirectives) {
+    UDirs.visitScopeChain(Initial, S);
+    UDirs.done();
+  }
+  
   // Lookup namespace scope, and global scope.
   // Unqualified name lookup in C++ requires looking into scopes
   // that aren't strictly lexical, and therefore we walk through the
-- 
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