X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=m4%2Fattributes.m4;h=97f094b07a2c303896c4174573093cd1901a2ec9;hp=aa53ef238027826b3f8d2d24fea27cc18c6aee71;hb=43bbf1acc8202de895e5449828a7b863c69fcc2f;hpb=d8c8508bad097c5cc354b684866a5b7a83fce394

diff --git a/m4/attributes.m4 b/m4/attributes.m4
index aa53ef238..97f094b07 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -34,15 +34,16 @@ 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'"
-           AC_LINK_IFELSE([AC_LANG_SOURCE([int a = 0; int main(void) { return a; } ])],
+           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'"])
            eval "AS_TR_SH([$2])='$cc_save_$2'"])
@@ -89,7 +90,7 @@ AC_DEFUN([CC_NOUNDEFINED], [
      *-freebsd* | *-openbsd*) ;;
      *)
         dnl First of all check for the --no-undefined variant of GNU ld. This allows
-        dnl for a much more readable commandline, so that people can understand what
+        dnl for a much more readable command line, so that people can understand what
         dnl it does without going to look for what the heck -z defs does.
         for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do
            CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"])