Include struct context info for parser/sema crashes. This

gives us:

Stack dump:
0.	using-directive.cpp:26:16: in compound statement ('{}')
1.	using-directive.cpp:26:16: parsing function body 'A::K1::foo'
2.	using-directive.cpp:25:3: parsing struct/union/class body 'A::K1'
3.	using-directive.cpp:5:1: parsing namespace 'A'
4.	clang using-directive.cpp 
Abort

for code like:

namespace A {
...
  class K1 {
    void foo() { <<crash>>

llvm-svn: 66124

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index b24b80eb711..6e0ffe5e2b6 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -1096,6 +1096,10 @@ ParseStructDeclaration(DeclSpec &DS,
 ///
 void Parser::ParseStructUnionBody(SourceLocation RecordLoc,
                                   unsigned TagType, DeclTy *TagDecl) {
+  PrettyStackTraceDecl CrashInfo(TagDecl, RecordLoc, Actions,
+                                 PP.getSourceManager(),
+                                 "parsing struct/union body");
+  
   SourceLocation LBraceLoc = ConsumeBrace();
   
   ParseScope StructScope(this, Scope::ClassScope|Scope::DeclScope);