Add the Clang specific -Wmissing-variable-declarations to WARNS=6.

This compiler flag enforces that that people either mark variables
static or use an external declarations for the variable, similar to how
-Wmissing-prototypes works for functions.

Due to the fact that Yacc/Lex generate code that cannot trivially be
changed to not warn because of this (lots of yy* variables), add a
NO_WMISSING_VARIABLE_DECLARATIONS that can be used to turn off this
specific compiler warning.

Announced on:	toolchain@

1 files changed, 2 insertions, 0 deletions

diff --git a/usr.sbin/jail/Makefile b/usr.sbin/jail/Makefile
index 00d7ff50b523..fb36defa8bf6 100644
--- a/usr.sbin/jail/Makefile
+++ b/usr.sbin/jail/Makefile
@@ -9,6 +9,8 @@ SRCS=	jail.c command.c config.c state.c jailp.h jaillex.l jailparse.y y.tab.h
 DPADD=	${LIBJAIL} ${LIBKVM} ${LIBUTIL} ${LIBL}
 LDADD=	-ljail -lkvm -lutil -ll
 
+NO_WMISSING_VARIABLE_DECLARATIONS=
+
 YFLAGS+=-v
 CFLAGS+=-I. -I${.CURDIR}