Re: [libvirt] [PATCH] build: silence a clang warning in virsh.c
On Tue, Nov 5, 2013 at 1:08 AM, Eric Blake <eblake(a)redhat.com> wrote:
On 11/04/2013 03:49 AM, Ryota Ozaki wrote:
> This patch shuts up the following warning of clang:
>
> virsh.c:2761:22: error: assigning to 'char *' from 'const char [6]'
discards qualifiers
> [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
> rl_readline_name = "virsh";
> ^ ~~~~~~~
Huh? <readline/readline.h> lists:
/* The name of the calling program. You should initialize this to
whatever was in argv[0]. It is used when parsing conditionals. */
extern const char *rl_readline_name;
at least for readline-devel-6.2 on Fedora 19. Why is clang failing to
see that the assignment is to something already marked const? Is it a
bug in your readline header?
Grrr. It seems that this is Mac OS X specific problem :-/
/usr/include/readline/readline.h of Mac OS X is still:
extern char *rl_readline_name;
The readline.h seems to be checked out from an old NetBSD
and not updated for a long time.
BTW recent *BSD seem to have migrated to the above
const char * version.
>
> Tested on Mac OS X 10.8.5 (clang-500.2.75) and
> Fedora 19 (gcc 4.8.1).
>
> Signed-off-by: Ryota Ozaki <ozaki.ryota(a)gmail.com>
> ---
> tools/virsh.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/virsh.c b/tools/virsh.c
> index 241c5b8..f45ee0a 100644
> --- a/tools/virsh.c
> +++ b/tools/virsh.c
> @@ -2758,7 +2758,7 @@ vshReadlineInit(vshControl *ctl)
> const char *histsize_str;
>
> /* Allow conditional parsing of the ~/.inputrc file. */
> - rl_readline_name = "virsh";
> + rl_readline_name = (char *) "virsh";
On the surface, this seems okay, but I'd rather know WHY we need it, and
also add a comment that casting away const is due to whatever the root
cause is.
So we need to write a comment about the Mac OS X's flaw.
I'll send a revised patch later.
Thanks,
ozaki-r
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org