From: Cheyenne Wills <cwills@sinenomine.net>
Date: Thu, 16 Jul 2020 21:07:15 +0000 (-0600)
Subject: autoconf: fix detection for fallthrough attribute
X-Git-Tag: openafs-devel-1_9_0~31
X-Git-Url: http://git.openafs.org/?p=openafs.git;a=commitdiff_plain;h=899b1af4183fb09fd55a36e3d10ffbdb9671a47e

autoconf: fix detection for fallthrough attribute

Due to bug <https://savannah.gnu.org/patch/?9949>,
ax_gcc_func_attribute.m4 fails to properly detect __attribute__((fallthrough))
in clang. Until this is fixed in autoconf-archive upstream, fix our
local copy of ax_gcc_func_attribute.m4, so we can detect
__attribute__((fallthrough)) to make --enable-checking work with clang.

Change-Id: I80a4557384f8e1438344e48bfe722e20c8773882
Reviewed-on: https://gerrit.openafs.org/14273
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
---

diff --git a/src/cf/ax_gcc_func_attribute.m4 b/src/cf/ax_gcc_func_attribute.m4
index 098c9aa..30bf4c1 100644
--- a/src/cf/ax_gcc_func_attribute.m4
+++ b/src/cf/ax_gcc_func_attribute.m4
@@ -77,7 +77,7 @@
 #   and this notice are preserved.  This file is offered as-is, without any
 #   warranty.
 
-#serial 9
+#serial 9 with local fix for fallthrough attribute
 
 AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
     AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1])
@@ -132,7 +132,7 @@ AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
                     int foo( void ) __attribute__(($1));
                 ],
                 [fallthrough], [
-                    int foo( void ) {switch (0) { case 1: __attribute__(($1)); case 2: break ; }};
+                    void foo( int x ) {switch (x) { case 1: __attribute__(($1)); case 2: break ; }};
                 ],
                 [flatten], [
                     int foo( void ) __attribute__(($1));