From eccce7e246a17e12a2afd6eabb9ac7c8d582db4e Mon Sep 17 00:00:00 2001
From: Argyrios Kyrtzidis <akyrtzi@gmail.com>
Date: Tue, 3 May 2011 18:45:38 +0000
Subject: [PATCH] Fix a double free when parsing malformed code. Fixes
 rdar://9173693.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130775 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Parse/ParseExprCXX.cpp        | 7 +++++--
 test/SemaTemplate/rdar9173693.cpp | 6 ++++++
 2 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 test/SemaTemplate/rdar9173693.cpp

diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index 8bf6f63d3e..eb491ef2bb 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -280,8 +280,11 @@ bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
                                       : TemplateId->TemplateNameLoc;
         SS.SetInvalid(SourceRange(StartLoc, CCLoc));
       }
-      
-      TemplateId->Destroy();
+
+      // If we are caching tokens we will process the TemplateId again,
+      // otherwise destroy it.
+      if (!PP.isBacktrackEnabled())
+        TemplateId->Destroy();
       continue;
     }
 
diff --git a/test/SemaTemplate/rdar9173693.cpp b/test/SemaTemplate/rdar9173693.cpp
new file mode 100644
index 0000000000..86b49545a3
--- /dev/null
+++ b/test/SemaTemplate/rdar9173693.cpp
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// <rdar://problem/9173693>
+template< bool C > struct assert { };
+template< bool > struct assert_arg_pred_impl { }; // expected-note 3 {{declared here}}
+template< typename Pred > assert<false> assert_not_arg( void (*)(Pred), typename assert_arg_pred<Pred>::type ); // expected-error 5 {{}}