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=f0bcf2421190af6d2a80529f45f1d9068bafaa42;hb=d2268a20a0bf99c5d26bee9048aa48b377c72949;hpb=cdefbd6aebc43c89aa1eafacd2edc10b605dfee7

diff --git a/m4/attributes.m4 b/m4/attributes.m4
index f0bcf2421..97f094b07 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -34,18 +34,19 @@ 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_COMPILE_IFELSE([AC_LANG_SOURCE([int a = 0; int main(void) { return a; } ])],
-                                    [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'"])
+          [eval "AS_TR_SH([cc_save_$2])='${$2}'"
+           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'"])
 
   AS_IF([eval test x$]AS_TR_SH([cc_cv_$2_$3])[ = xyes],
         [eval "$1='${$1} $3'"])
@@ -89,13 +90,13 @@ AC_DEFUN([CC_NOUNDEFINED], [
      *-freebsd* | *-openbsd*) ;;
      *)
         dnl First of all check for the --no-undefined variant of GNU ld. This allows
-        dnl for a much more readable commandline, so that people can understand what
+        dnl for a much more readable command line, so that people can understand what
         dnl it does without going to look for what the heck -z defs does.
         for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do
-          CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"])
-	  break
+           CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"])
+           break
         done
-	;;
+     ;;
   esac
 
   AC_SUBST([LDFLAGS_NOUNDEFINED])
@@ -231,8 +232,8 @@ AC_DEFUN([CC_FLAG_VISIBILITY], [
     [cc_flag_visibility_save_CFLAGS="$CFLAGS"
      CFLAGS="$CFLAGS $cc_cv_werror"
      CC_CHECK_CFLAGS_SILENT([-fvisibility=hidden],
-	cc_cv_flag_visibility='yes',
-	cc_cv_flag_visibility='no')
+     cc_cv_flag_visibility='yes',
+     cc_cv_flag_visibility='no')
      CFLAGS="$cc_flag_visibility_save_CFLAGS"])
 
   AS_IF([test "x$cc_cv_flag_visibility" = "xyes"],
@@ -252,7 +253,7 @@ AC_DEFUN([CC_FUNC_EXPECT], [
        [int some_function() {
         int a = 3;
         return (int)__builtin_expect(a, 3);
-	}])],
+     }])],
        [cc_cv_func_expect=yes],
        [cc_cv_func_expect=no])
      CFLAGS="$ac_save_CFLAGS"