3 files changed, 13 insertions, 5 deletions
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 8af57ab9b51..61e781d8b18 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2010-07-08  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	* c-common.h: Include diagnostic-core.h. Error if already
+	included.
+	* c-semantics.c: Do not define GCC_DIAG_STYLE here.
+
 2010-07-03  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
 	* c-family/c-common.c (IN_GCC_FRONTEND): Do not undef.
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 5784746e90a..78cf4fdb2b5 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -28,9 +28,15 @@ along with GCC; see the file COPYING3.  If not see
 
 /* In order for the format checking to accept the C frontend
    diagnostic framework extensions, you must include this file before
-   toplev.h, not after.  The C front end formats are a subset of those
+   diagnostic-core.h, not after.  The C front end formats are a subset of those
    for C++, so they are the appropriate set to use in common code;
    cp-tree.h overrides this for C++.  */
+#if defined(GCC_DIAGNOSTIC_CORE_H)
+#error \
+In order for the format checking to accept the C front end diagnostic \
+framework extensions, you must include this file before diagnostic-core.h \
+never after.
+#endif
 #ifndef GCC_DIAG_STYLE
 #define GCC_DIAG_STYLE __gcc_cdiag__
 #endif
diff --git a/gcc/c-family/c-semantics.c b/gcc/c-family/c-semantics.c
index 683655f77c0..0eccd5189e4 100644
--- a/gcc/c-family/c-semantics.c
+++ b/gcc/c-family/c-semantics.c
@@ -27,10 +27,6 @@ along with GCC; see the file COPYING3.  If not see
 #include "function.h"
 #include "splay-tree.h"
 #include "c-common.h"
-/* In order for the format checking to accept the C frontend
-   diagnostic framework extensions, you must define this token before
-   including toplev.h.  */
-#define GCC_DIAG_STYLE __gcc_cdiag__
 #include "toplev.h"
 #include "flags.h"
 #include "output.h"