AT_BISON_CHECK([-d -o AT_SKEL_CC_IF([$1.cc $1.yy], [$1.c $1.y])])
# C++ output relies on namespaces and still uses yy a lot.
AT_SKEL_CC_IF([],
- [AT_CHECK([$EGREP -i yy $1.h | $EGREP -v 'YY(DEBUG|PARSE_PARAM)'], [1])])
+ [AT_CHECK([$EGREP yy $1.h], [1])])
+
+# Ignore comments. Ignore YYPARSE_PARAM. YYDEBUG (not renamed) can be
+# read, but not changed.
+AT_CHECK([[sed -ne 's,/\*[^*]*\*/,,g;s,//.*,,' \
+ -e '/YY/p' ]$1.AT_SKEL_CC_IF([hh], [h])[ |
+ $EGREP -wv '(YYPARSE_PARAM|defined YYDEBUG|if YYDEBUG)']],
+ [1])
AT_LANG_COMPILE([$1.o])
AT_BISON_OPTION_POPDEFS
])