tweak redefinition of a typedef a bit to fix a couple of problems:

1. We had logic in sema to decide whether or not to emit the error
   based on manually checking whether in a system header file.
2. we were allowing redefinitions of typedefs in class scope in C++
   if in header file.
3. there was no way to force typedef redefinitions to be accepted
   by the C compiler, which annoys me when stripping linemarkers out
   of .i files.

The fix is to split the C++ class typedef redefinition path from the
C path, and change the C path to be a warning that normally maps to
error.  This causes it to properly be ignored in system headers, 
etc. and gives us a way to control it.  Passing 
-Wtypedef-redefinition now turns the error into a warning.

One behavior change is that we now diagnose cases where you redefine
a typedef in your .c file that was defined in a header file.  This
seems like reasonable behavior, and the diagnostic now indicates that
it can be controlled with -Wtypedef-redefinition.

llvm-svn: 69391

2 files changed, 2 insertions, 8 deletions

diff --git a/clang/test/Preprocessor/line-directive.c b/clang/test/Preprocessor/line-directive.c
index 07cfa65e946..66efae94d5c 100644
--- a/clang/test/Preprocessor/line-directive.c
+++ b/clang/test/Preprocessor/line-directive.c
@@ -40,7 +40,7 @@
 
 # 192 "glomp.h" // not a system header.
 typedef int x;  // expected-note {{previous definition is here}}
-typedef int x;  // expected-error {{redefinition of 'x'}}
+typedef int x;  // expected-error {{redefinition of typedef 'x' is invalid in C}}
 
 # 192 "glomp.h" 3 // System header.
 typedef int y;  // ok
@@ -59,4 +59,4 @@ typedef int z1;  // ok
 # 42 "blonk.h"  // DOES change system headerness.
 
 typedef int w;  // expected-note {{previous definition is here}}
-typedef int w;  // expected-error {{redefinition of 'w'}}
+typedef int w;  // expected-error {{redefinition of typedef 'w' is invalid in C}}
diff --git a/clang/test/Sema/typedef-redef.c b/clang/test/Sema/typedef-redef.c
index 9ec622612ec..9a1c4887324 100644
--- a/clang/test/Sema/typedef-redef.c
+++ b/clang/test/Sema/typedef-redef.c
@@ -1,11 +1,5 @@
 // RUN: clang-cc -fsyntax-only -verify %s
 
-// size_t coming from a system header.
-#include <stddef.h>
-typedef __SIZE_TYPE__ size_t;
-
-
-
 typedef const int x; // expected-note {{previous definition is here}}
 extern x a;
 typedef int x;  // expected-error {{typedef redefinition with different types}}