From b50e3b52fb0be6f6fd4894896143c9bb3251f85e Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Fri, 22 Sep 2023 11:45:01 +0100
Subject: [PATCH] Detect Bison -Wcounterexamples support in configure script

---
 Makefile.am            |  1 +
 configure.ac           | 10 ++++++++++
 src/vlog/Makemodule.am |  2 --
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index a79888a5..bb0d1f77 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -8,6 +8,7 @@ AM_CPPFLAGS = -I$(top_srcdir)/thirdparty -I$(top_srcdir)/src
 AM_CFLAGS   = -Wall $(EXTRA_CFLAGS) $(LTO_FLAG)
 AM_CXXFLAGS = -Wall $(EXTRA_CFLAGS) $(LTO_FLAG)
 AM_LDFLAGS  = $(EXTRA_LDFLAGS) $(LLVM_LDFLAGS)
+AM_YFLAGS   = --locations $(EXTRA_YFLAGS)
 
 AM_CC       = $(PTHREAD_CC)
 AM_CFLAGS   += $(PTHREAD_CFLAGS)
diff --git a/configure.ac b/configure.ac
index 17a80752..1b43c3ee 100644
--- a/configure.ac
+++ b/configure.ac
@@ -80,6 +80,7 @@ AM_CONDITIONAL([GNULIB_STRNDUP], [test "x$ac_cv_func_strndup" != xyes])
 
 EXTRA_CFLAGS=
 EXTRA_LDFLAGS=
+EXTRA_YFLAGS=
 
 # Need to prevent GCC calling strndup builtin if using gnulib version
 if test "x$ac_cv_func_strndup" != xyes; then
@@ -142,6 +143,14 @@ AM_CONDITIONAL([ENABLE_VERILOG], [test x$enable_verilog = xyes])
 AS_IF([test x$enable_verilog = xyes],
       [AX_PROG_BISON([], [AC_MSG_ERROR(GNU Bison not found)])
        AC_DEFINE_UNQUOTED([ENABLE_VERILOG], [1], [Verilog support enabled])])
+
+AS_IF([test "$ax_cv_prog_bison" = "yes"],
+      [AC_MSG_CHECKING([if ${YACC%% *} supports -Wcounterexamples])
+       AS_IF([$YACC -Wcounterexamples --version 2>/dev/null >/dev/null],
+             [AC_MSG_RESULT([yes])
+              AX_APPEND_FLAG([-Wcounterexamples], [EXTRA_YFLAGS])],
+             [AC_MSG_RESULT([no])])])
+
 AX_PROG_FLEX([], [AC_MSG_ERROR(Flex not found)])
 
 case $host_os in
@@ -529,6 +538,7 @@ AM_CONDITIONAL([ENABLE_GCOV], [test x$enable_gcov = xyes])
 
 AC_SUBST(EXTRA_CFLAGS)
 AC_SUBST(EXTRA_LDFLAGS)
+AC_SUBST(EXTRA_YFLAGS)
 
 AS_IF([test x$enable_maintainer_mode = xyes ],
       [AC_PATH_PROG([MANDOC], [mandoc])])
diff --git a/src/vlog/Makemodule.am b/src/vlog/Makemodule.am
index 59061d29..bc82409f 100644
--- a/src/vlog/Makemodule.am
+++ b/src/vlog/Makemodule.am
@@ -12,5 +12,3 @@ lib_libnvc_a_SOURCES += \
 	src/vlog/vlog-parse.y \
 	src/vlog/vlog-sem.c
 endif
-
-AM_YFLAGS = --locations # -Wcounterexamples
-- 
2.39.2