[systemd-commits] m4/attributes.m4

[David Herrmann]

 m4/attributes.m4 |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

New commits:
commit 43bbf1acc8202de895e5449828a7b863c69fcc2f
Author: David Herrmann <dh.herrmann at gmail.com>
Date:   Tue Feb 24 17:49:48 2015 +0100

    build: make sure to test for -Wflag instead of -Wno-flag
    
    gcc does not support testing for negated warnings. See here for details:
        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63499
    
    This patch changes CC_CHECK_FLAG_APPEND to always test for the non-negated
    warnings.

diff --git a/m4/attributes.m4 b/m4/attributes.m4
index ac3c662..97f094b 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -34,14 +34,15 @@ dnl this special exception to the GPL to apply to your modified version as
 dnl well.
 
 dnl Check if FLAG in ENV-VAR is supported by compiler and append it
-dnl to WHERE-TO-APPEND variable
+dnl to WHERE-TO-APPEND variable. Note that we invert -Wno-* checks to
+dnl -W* as gcc cannot test for negated warnings.
 dnl CC_CHECK_FLAG_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG])
 
 AC_DEFUN([CC_CHECK_FLAG_APPEND], [
   AC_CACHE_CHECK([if $CC supports flag $3 in envvar $2],
                  AS_TR_SH([cc_cv_$2_$3]),
           [eval "AS_TR_SH([cc_save_$2])='${$2}'"
-           eval "AS_TR_SH([$2])='-Werror $3'"
+           eval "AS_TR_SH([$2])='-Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
            AC_LINK_IFELSE([AC_LANG_SOURCE([int main(void) { return 0; } ])],
                           [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
                           [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])