stdalign: port to Clang 3.0

[gnulib.git] / m4 / stdalign.m4

diff --git a/m4/stdalign.m4 b/m4/stdalign.m4
index da64dc6..2641dce 100644 (file)
--- a/m4/stdalign.m4
+++ b/m4/stdalign.m4
@@ -9,9 +9,24 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_STDALIGN_H],
 [
-  AC_CHECK_HEADERS_ONCE([stdalign.h])
+  AC_CACHE_CHECK([for working stdalign.h],
+    [gl_cv_header_working_stdalign_h],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdalign.h>
+            int align_int = alignof (int) + _Alignof (double);
 
-  if test $ac_cv_header_stdalign_h = yes; then
+            /* Test _Alignas only on platforms where gnulib can help.  */
+            #if \
+                (__GNUC__ || __IBMC__ || __IBMCPP__ \
+                 || 0x5110 <= __SUNPRO_C || 1300 <= _MSC_VER)
+              int alignas (8) alignas_int = 1;
+            #endif
+          ]])],
+       [gl_cv_header_working_stdalign_h=yes],
+       [gl_cv_header_working_stdalign_h=no])])
+
+  if test $gl_cv_header_working_stdalign_h = yes; then
     STDALIGN_H=''
   else
     STDALIGN_H='stdalign.h'