+
+# AT_BISON_CHECK_(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
+# --------------------------------------------------
+# Low-level macro to run bison once.
+m4_define([AT_BISON_CHECK_],
+[AT_CHECK(AT_QUELL_VALGRIND[[ bison ]]$@)])
+
+
+# AT_BISON_CHECK_WARNINGS(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
+# ----------------------------------------------------------
+# Check that warnings (if some are expected) are correctly
+# turned into errors with -Werror, etc.
+m4_define([AT_BISON_CHECK_WARNINGS],
+[m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
+ [m4_null_if([$2], [AT_BISON_CHECK_WARNINGS_($@)])])])
+
+m4_define([AT_BISON_CHECK_WARNINGS_],
+[[# Defining POSIXLY_CORRECT causes bison to complain if options
+ # are added after the grammar file name, so skip these checks
+ # in that case.
+ if test -z "${POSIXLY_CORRECT+set}"; then
+ ]AT_SAVE_SPECIAL_FILES[
+
+ # To avoid expanding it repeatedly, store specified stdout.
+ ]AT_DATA([expout], [$3])[
+
+ # Run with -Werror.
+ ]AT_BISON_CHECK_([$1[ -Werror]], [[1]], [expout], [stderr])[
+
+ # Build expected stderr up to and including the "warnings being
+ # treated as errors" message.
+ ]AT_DATA([[at-bison-check-warnings]], [$4])[
+ at_bison_check_first=`sed -n \
+ '/: warning: /{=;q;}' at-bison-check-warnings`
+ : ${at_bison_check_first:=1}
+ at_bison_check_first_tmp=`sed -n \
+ '/conflicts: [0-9].*reduce$/{=;q;}' at-bison-check-warnings`
+ : ${at_bison_check_first_tmp:=1}
+ if test $at_bison_check_first_tmp -lt $at_bison_check_first; then
+ at_bison_check_first=$at_bison_check_first_tmp
+ fi
+ if test $at_bison_check_first -gt 1; then
+ sed -n "1,`expr $at_bison_check_first - 1`"p \
+ at-bison-check-warnings > experr
+ fi
+ echo ']AT_BISON_WERROR_MSG[' >> experr
+
+ # Finish building expected stderr and check. Unlike warnings,
+ # complaints cause bison to exit early. Thus, with -Werror, bison
+ # does not necessarily report all warnings that it does without
+ # -Werror, but it at least reports one.
+ at_bison_check_last=`sed -n '$=' stderr`
+ : ${at_bison_check_last:=1}
+ at_bison_check_last=`expr $at_bison_check_last - 1`
+ sed -n "$at_bison_check_first,$at_bison_check_last"p \
+ at-bison-check-warnings >> experr
+ ]AT_CHECK([[sed 's,.*/\(]AT_BISON_WERROR_MSG[\)$,\1,' \
+ stderr 1>&2]], [[0]], [[]], [experr])[
+
+ # Now check --warnings=error.
+ cp stderr experr
+ ]AT_BISON_CHECK_([$1[ --warnings=error]], [[1]], [expout], [experr])[
+
+ # Now check -Wnone and --warnings=none by making sure that
+ # -Werror doesn't change the exit status when -Wnone or
+ # --warnings=none is specified.
+ ]AT_BISON_CHECK_([$1[ -Wnone -Werror]], [[0]], [expout])[
+ ]AT_BISON_CHECK_([$1[ --warnings=none -Werror]], [[0]], [expout])[
+
+ ]AT_RESTORE_SPECIAL_FILES[
+fi]dnl
+])
+