Bison: A bit more verbose error messages in config.

Makefile.in

@@ -10,6 +10,7 @@ CPPFLAGS=-I$(objdir) -I$(srcdir) @CPPFLAGS@
 CFLAGS=$(CPPFLAGS) @CFLAGS@
 LDFLAGS=@LDFLAGS@
 M4FLAGS=@M4FLAGS@
+BISONFLAGS=@BISONFLAGS@
 LIBS=@LIBS@
 DAEMON_LIBS=@DAEMON_LIBS@
 CLIENT_LIBS=@CLIENT_LIBS@

aclocal.m4

@@ -185,9 +185,11 @@ AC_DEFUN([BIRD_CHECK_BISON_VERSION],
       ;;
     2.*)
       bird_bison_synclines=no
+      bird_bison_enhanced_error=no
       ;;
     3.* | 4.* | 5.* | 6.* | 7.* | 8.* | 9.*)
       bird_bison_synclines=yes
+      bird_bison_enhanced_error=yes
       ;;
     *)
       AC_MSG_ERROR([Couldn't parse Bison version $$1. Call the developers for help.])

conf/Makefile

@@ -20,7 +20,7 @@ $(o)commands.h: | $(s)gen_commands.m4 $(srcdir)/client/cmds.m4
 $(o)cf-parse.tab.h: $(o)cf-parse.tab.c
 
 $(o)cf-parse.tab.c: $(o)cf-parse.y
-	$(BISON) $(BISON_DEBUG) -dv -pcf_ -b $(@:.tab.c=) $<
+	$(BISON) $(BISON_DEBUG) $(BISONFLAGS) -dv -pcf_ -b $(@:.tab.c=) $<
 
 $(o)cf-lex.c: $(s)cf-lex.l
 	$(FLEX) $(FLEX_DEBUG) -s -B -8 -Pcf_ -o$@ $<

configure.ac

@@ -164,7 +164,12 @@ if test "$bird_bison_synclines" = yes; then
   M4FLAGS="$M4FLAGS -s"
 fi
 
+if test "$bird_bison_enhanced_error" = yes; then
+  BISONFLAGS="$BISONFLAGS -Dparse.lac=full -Dparse.error=verbose"
+fi
+
 AC_SUBST([M4FLAGS])
+AC_SUBST([BISONFLAGS])
 
 BIRD_CHECK_PROG_FLAVOR_GNU([$M4],
   [],