From d73d7add37f751a89e99bcc0fb1c0fcb82d98144 Mon Sep 17 00:00:00 2001
From: John Thompson <John.Thompson.JTSoftware@gmail.com>
Date: Fri, 23 Oct 2009 02:21:17 +0000
Subject: Fixed undefined behavior in pushMappings when the stack has to
 resize.

llvm-svn: 84924
---
 clang/lib/Basic/Diagnostic.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
index d665e49126d..fbc73131165 100644
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -230,6 +230,8 @@ Diagnostic::~Diagnostic() {
 
 
 void Diagnostic::pushMappings() {
+  // Avoids undefined behavior when the stack has to resize.
+  DiagMappingsStack.reserve(DiagMappingsStack.size() + 1);
   DiagMappingsStack.push_back(DiagMappingsStack.back());
 }
 
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