bison --yacc --name-prefix=__gettext --output /tmp/glibc-2.28/build-glibc-2.28/intl/plural.c plural.y
plural.y:46.1-7: error: POSIX Yacc does not support %define [-Werror=yacc]
%define api.pure full
^~~~~~~
plural.y:47.1-7: error: POSIX Yacc does not support %expect [-Werror=yacc]
%expect 7
^~~~~~~
make[2]: *** [Makefile:46: /tmp/glibc-2.28/build-glibc-2.28/intl/plural.c] Error 1