Revert all usages of gcc's __extension__ keyword, and instead assert

that our headers are not built with __GNUC__ and __STRICT_ANSI__.

__extension__ had some weird (and buggy) behaviours when nested which
make it a risky proposition for general usage in our header
files. Better to disallow -ansi, -std=c99, and similar gcc options
when building against Xen headers.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

2 files changed, 2 insertions, 5 deletions

diff --git a/tools/include/xen-foreign/mkchecker.py b/tools/include/xen-foreign/mkchecker.py
index 264bf799b5..66c17b19e9 100644
--- a/tools/include/xen-foreign/mkchecker.py
+++ b/tools/include/xen-foreign/mkchecker.py
@@ -19,9 +19,6 @@ f.write('''
 #include <stdlib.h>
 #include <stddef.h>
 #include <inttypes.h>
-
-#define __anonymous_struct __extension__ struct
-#define __anonymous_union __extension__ union
 ''');
 
 for a in archs:
diff --git a/tools/include/xen-foreign/mkheader.py b/tools/include/xen-foreign/mkheader.py
index 17873e4842..8b249e3dfc 100644
--- a/tools/include/xen-foreign/mkheader.py
+++ b/tools/include/xen-foreign/mkheader.py
@@ -37,8 +37,8 @@ inttypes["x86_64"] = {
     "xen_pfn_t"     : "__align8__ uint64_t",
 };
 header["x86_64"] = """
-#ifdef __GNUC__
-# define __DECL_REG(name) __anonymous_union { uint64_t r ## name, e ## name; }
+#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
+# define __DECL_REG(name) union { uint64_t r ## name, e ## name; }
 # define __align8__ __attribute__((aligned (8)))
 #else
 # define __DECL_REG(name) uint64_t r ## name