Correct handling of _Pragma macro inside a macro argument.

If we are pre-expanding a macro argument don't actually "activate"
the pragma at that point, activate the pragma whenever we encounter
it again in the token stream.
This ensures that we will activate it in the correct location
or that we will ignore it if it never enters the token stream, e.g:

     \#define EMPTY(x)
     \#define INACTIVE(x) EMPTY(x)
     INACTIVE(_Pragma("clang diagnostic ignored \"-Wconversion\""))

This also fixes the crash in rdar://11168596.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153959 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 0 deletions

diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index 591a4498eb..055008fd44 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -124,6 +124,9 @@ class Preprocessor : public RefCountedBase<Preprocessor> {
   /// \brief Whether we have already loaded macros from the external source.
   mutable bool ReadMacrosFromExternalSource : 1;
 
+  /// \brief True if we are pre-expanding macro arguments.
+  bool InMacroArgPreExpansion;
+
   /// Identifiers - This is mapping/lookup information for all identifiers in
   /// the program, including program keywords.
   mutable IdentifierTable Identifiers;