Simplify FindExternalVisibleDeclsByName by making it return a bool indicating

if it found any decls, rather than returning a list of found decls. This
removes a returning-ArrayRef-to-deleted-storage bug from
MultiplexExternalSemaSource (in code not exercised by any of the clang
binaries), reduces the work required in the found-no-decls case with PCH, and
importantly removes the need for DeclContext::lookup to be reentrant.

No functionality change intended!

llvm-svn: 174576

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 27a91cb7e66..52ecdeb3183 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1186,7 +1186,15 @@ DeclContext::lookup(DeclarationName Name) {
     }
 
     ExternalASTSource *Source = getParentASTContext().getExternalSource();
-    return Source->FindExternalVisibleDeclsByName(this, Name);
+    if (Source->FindExternalVisibleDeclsByName(this, Name)) {
+      if (StoredDeclsMap *Map = LookupPtr.getPointer()) {
+        StoredDeclsMap::iterator I = Map->find(Name);
+        if (I != Map->end())
+          return I->second.getLookupResult();
+      }
+    }
+
+    return lookup_result(lookup_iterator(0), lookup_iterator(0));
   }
 
   StoredDeclsMap *Map = LookupPtr.getPointer();