1 files changed, 18 insertions, 2 deletions

diff --git a/gl/m4/stddef_h.m4 b/gl/m4/stddef_h.m4
index a2322ebb..84d3bae8 100644
--- a/gl/m4/stddef_h.m4
+++ b/gl/m4/stddef_h.m4
@@ -1,5 +1,6 @@
-# stddef_h.m4 serial 13
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# stddef_h.m4
+# serial 14
+dnl Copyright (C) 2009-2024 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -68,6 +69,21 @@ AC_DEFUN_ONCE([gl_STDDEF_H],
     GL_GENERATE_STDDEF_H=true
   fi
 
+  AC_CACHE_CHECK([for unreachable],
+    [gl_cv_func_unreachable],
+    [AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stddef.h>
+          ]],
+          [[unreachable ();
+          ]])],
+       [gl_cv_func_unreachable=yes],
+       [gl_cv_func_unreachable=no])
+    ])
+  if test $gl_cv_func_unreachable = no; then
+    GL_GENERATE_STDDEF_H=true
+  fi
+
   if $GL_GENERATE_STDDEF_H; then
     gl_NEXT_HEADERS([stddef.h])
   fi