[PATCH] extern-inline: support old GCC 'inline'

[Paul Eggert]

* m4/extern-inline.m4 (gl_EXTERN_INLINE): Use pre-C99 GCC 'inline'
if available.  This applies to GCC versions 2.7 through 4.2, or
when newer GCC is using -fgnu89-inline.  The goal is to address
some of the performance issues mentioned by Bruno Haible in
<http://lists.gnu.org/archive/html/bug-gnulib/2012-08/msg00097.html>.
---
 ChangeLog           |    9 +++++++++
 m4/extern-inline.m4 |   30 ++++++++++++++++++++++--------
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 890ce17..9d9266e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2012-08-20  Paul Eggert  <address@hidden>
+
+       extern-inline: support old GCC 'inline'
+       * m4/extern-inline.m4 (gl_EXTERN_INLINE): Use pre-C99 GCC 'inline'
+       if available.  This applies to GCC versions 2.7 through 4.2, or
+       when newer GCC is using -fgnu89-inline.  The goal is to address
+       some of the performance issues mentioned by Bruno Haible in
+       <http://lists.gnu.org/archive/html/bug-gnulib/2012-08/msg00097.html>.
+
 2012-08-20  Eric Blake  <address@hidden>
 
        maint.mk: avoid redundant file name in message
diff --git a/m4/extern-inline.m4 b/m4/extern-inline.m4
index 187a335..12f24fa 100644
--- a/m4/extern-inline.m4
+++ b/m4/extern-inline.m4
@@ -21,20 +21,34 @@ AC_DEFUN([gl_EXTERN_INLINE],
 #if __GNUC__ ? __GNUC_STDC_INLINE__ : 199901L <= __STDC_VERSION__
 # define _GL_INLINE inline
 # define _GL_EXTERN_INLINE extern inline
-# if (__GNUC__ == 4 && 6 <= __GNUC_MINOR__) || 4 < __GNUC__
-#  define _GL_INLINE_HEADER_BEGIN \
-     _Pragma ("GCC diagnostic push") \
-     _Pragma ("GCC diagnostic ignored \"-Wmissing-prototypes\"") \
-     _Pragma ("GCC diagnostic ignored \"-Wmissing-declarations\"")
-#  define _GL_INLINE_HEADER_END \
-     _Pragma ("GCC diagnostic pop")
+#elif 2 < __GNUC__ + (7 <= __GNUC_MINOR__)
+# if __GNUC_GNU_INLINE__
+   /* __gnu_inline__ suppresses a GCC 4.2 diagnostic.  */
+#  define _GL_INLINE extern inline __attribute__ ((__gnu_inline__))
+# else
+#  define _GL_INLINE extern inline
 # endif
+# define _GL_EXTERN_INLINE extern
 #else
 # define _GL_INLINE static inline
 # define _GL_EXTERN_INLINE static inline
 #endif
 
-#ifndef _GL_INLINE_HEADER_BEGIN
+#if 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
+# if __GNUC_STDC_INLINE__
+#  define _GL_INLINE_HEADER_CONST_PRAGMA
+# else
+#  define _GL_INLINE_HEADER_CONST_PRAGMA \
+     _Pragma ("GCC diagnostic ignored \"-Wsuggest-attribute=const\"")
+# endif
+# define _GL_INLINE_HEADER_BEGIN \
+    _Pragma ("GCC diagnostic push") \
+    _Pragma ("GCC diagnostic ignored \"-Wmissing-prototypes\"") \
+    _Pragma ("GCC diagnostic ignored \"-Wmissing-declarations\"") \
+    _GL_INLINE_HEADER_CONST_PRAGMA
+# define _GL_INLINE_HEADER_END \
+    _Pragma ("GCC diagnostic pop")
+#else
 # define _GL_INLINE_HEADER_BEGIN
 # define _GL_INLINE_HEADER_END
 #endif])
-- 
1.7.6.5