build-sys: avoid icc warnings "ignoring unknown option"

Our macro UL_WARN_ADD could not discover these ones:
icc: command line warning #10006: ignoring unknown option '-Wmissing-parameter-type'
icc: command line warning #10006: ignoring unknown option '-Wredundant-decls'
icc: command line warning #10006: ignoring unknown option '-Wunused-result'
icc: command line warning #10006: ignoring unknown option '-Wnested-externs'

We need to use AC_LANG_WERROR.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>

diff --git a/m4/compiler.m4 b/m4/compiler.m4
index 062f9362302d65de58f31a5ae83f1a71c2bcc05e..058c73f069035721771b6242496dd456caedb8cd 100644 (file)
--- a/m4/compiler.m4
+++ b/m4/compiler.m4
@@ -21,11 +21,18 @@ AC_DEFUN([UL_WARN_ADD], [
   m4_define([warnvarname], m4_default([$2],WARN_CFLAGS))
   AS_VAR_PUSHDEF([ul_Warn], [ul_cv_warn_$1])dnl
   AC_CACHE_CHECK([whether compiler handles $1], m4_defn([ul_Warn]), [
+    # store AC_LANG_WERROR status, then turn it on
+    save_ac_[]_AC_LANG_ABBREV[]_werror_flag="${ac_[]_AC_LANG_ABBREV[]_werror_flag}"
+    AC_LANG_WERROR
+
     ul_save_CPPFLAGS="$CPPFLAGS"
     CPPFLAGS="-Werror ${CPPFLAGS} $1"
     AC_PREPROC_IFELSE([AC_LANG_PROGRAM([])],
                       [AS_VAR_SET(ul_Warn, [yes])],
                       [AS_VAR_SET(ul_Warn, [no])])
+    # restore AC_LANG_WERROR
+    ac_[]_AC_LANG_ABBREV[]_werror_flag="${save_ac_[]_AC_LANG_ABBREV[]_werror_flag}"
+
     CPPFLAGS="$ul_save_CPPFLAGS"
   ])
   AS_VAR_IF(ul_Warn, [yes], [UL_AS_VAR_APPEND(warnvarname, [" $1"])])