Date: Tue, 2 Aug 2005 01:40:12 -0400 From: Craig Rodrigues <rodrigc@crodrigues.org> To: freebsd-current@freebsd.org Subject: Why -Wredundant-decls in sys/conf/kern.mk? Message-ID: <20050802054012.GA72632@crodrigues.org>
next in thread | raw e-mail | index | archive | help
Hi,
I am looking into getting the kernel to compile with gcc 4.0,
and encountered something which I am not sure about.
In sys/conf/kern.mk, why do we have -Wredundant-decls in the
CWARNFLAGS:
CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
I have no problems with the other warning flags.
However -Wredundant-decls warns for:
`-Wredundant-decls'
Warn if anything is declared more than once in the same scope,
even in cases where multiple declaration is valid and changes
nothing.
This warning causes gcc to emit a warning for legal C code,
that normally not even -Wall would complain about.
For example, gcc compiles this code compiles fine, even with -Wall:
struct a { }; static struct a b; static struct a b = { };
but emits a warning with -Wredundant-decls:
r.c:1: warning: redundant redeclaration of 'b'
r.c:1: warning: previous declaration of 'b' was here
There are places in the kernel that want to forward declare
a struct as static, and then implement it later on.
Since it is legal in C to do this, are we gaining anything
by having this flag in the kernel's CWARNFLAGS?
Does -Wredundant-decls warn against other things that are useful
to warn against?
Sorry if this is a silly question....I'm not a C expert.
Thanks.
--
Craig Rodrigues
rodrigc@crodrigues.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20050802054012.GA72632>