Don't attempt to merge a deserialized declaration with existing

declarations in the AST unless modules are enabled. This case doesn't
come up with precompiled headers, and it isn't cheap.

llvm-svn: 147451

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index abab88a9c6c..82f6fae4a03 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1512,6 +1512,10 @@ ASTDeclReader::VisitRedeclarable(Redeclarable<T> *D) {
 template<typename T>
 void ASTDeclReader::mergeRedeclarable(Redeclarable<T> *D, 
                                       RedeclarableResult &Redecl) {
+  // If modules are not available, there is no reason to perform this merge.
+  if (!Reader.getContext().getLangOptions().Modules)
+    return;
+  
   if (FindExistingResult ExistingRes = findExisting(static_cast<T*>(D))) {
     if (T *Existing = ExistingRes) {
       T *ExistingCanon = Existing->getCanonicalDecl();