[libvirt] [PATCH] build: silence a clang warning in virsh.c

[Eric Blake]

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?

> 
> 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 at 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.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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