Eliminate a race condition with the global module index.

Essentially, a module file on disk could change size between the time
we stat() it and the time we open it, and we need to be robust against
such a problem.

llvm-svn: 174529

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/Serialization/GlobalModuleIndex.cpp b/clang/lib/Serialization/GlobalModuleIndex.cpp
index 72165bc..5b2ab91 100644
--- a/clang/lib/Serialization/GlobalModuleIndex.cpp
+++ b/clang/lib/Serialization/GlobalModuleIndex.cpp
@@ -536,7 +536,8 @@ namespace {
 bool GlobalModuleIndexBuilder::loadModuleFile(const FileEntry *File) {
   // Open the module file.
   OwningPtr<llvm::MemoryBuffer> Buffer;
-  Buffer.reset(FileMgr.getBufferForFile(File));
+  std::string ErrorStr;
+  Buffer.reset(FileMgr.getBufferForFile(File, &ErrorStr, /*isVolatile=*/true));
   if (!Buffer) {
     return true;
   }