-# AT_BISON_CHECK_NO_XML(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
-# --------------------------------------------------------
-# Same as AT_BISON_CHECK except don't perform XML/XSLT checks. This is useful
-# when a tortured grammar's XML is known to be too large for xsltproc to
-# handle.
-m4_define([AT_BISON_CHECK_NO_XML],
-[AT_CHECK(m4_if(m4_quote($2), [0], [], m4_quote($2), [], [],
- [AT_QUELL_VALGRIND ])[[bison ]]$@)
-m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
- m4_quote(m4_if(m4_quote($2), [], [0], [$2])), [0], [[
- # Defining POSIXLY_CORRECT causes bison to complain if options
+
+# AT_BISON_CHECK_(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
+# --------------------------------------------------
+# Low-level macro to run bison once.
+m4_define([AT_BISON_CHECK_],
+[AT_CHECK(AT_QUELL_VALGRIND[[ bison ]]$@)])
+
+
+# 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