Re: [Qemu-devel] [PATCH] curses: fix wchar_t printf warning

[Eric Blake <eblake@redhat.com>]

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On 4/2/19 2:30 AM, Gerd Hoffmann wrote:
> On some systems wchar_t is "long int", on others just "int".

And elsewhere, it's 'short'.

> So go cast to "long int" and adjust the printf format accordingly.
> 
> Reported-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  ui/curses.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/ui/curses.c b/ui/curses.c
> index cc6d6da68463..fb63945188b2 100644
> --- a/ui/curses.c
> +++ b/ui/curses.c
> @@ -453,8 +453,8 @@ static uint16_t get_ucs(wchar_t wch, iconv_t conv)
>      swch = sizeof(wch);
>  
>      if (iconv(conv, &pwch, &swch, &pch, &sch) == (size_t) -1) {
> -        fprintf(stderr, "Could not convert 0x%02x from WCHAR_T to UCS-2: %s\n",
> -                        wch, strerror(errno));
> +        fprintf(stderr, "Could not convert 0x%02lx from WCHAR_T to UCS-2: %s\n",
> +                (unsigned long)wch, strerror(errno));

Sadly, I think you are right that a cast is necessary; there is no
reserved printf character for printing wchar_t as an integer, and the
width of wchar_t is unspecified (on 32-bit systems where it is 'long
int', it does not promote to 'int').

You could have also stuck with %02x and (int)wch, for less typing, but
it's not worth the respin.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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