Re: [Qemu-devel] [PULL for-1.7 v2 3/6] acpi-build: fix build on glib < 2.22

[Michael S. Tsirkin]

On Tue, Nov 26, 2013 at 06:37:43AM +1000, Richard Henderson wrote:
> On 11/26/2013 06:31 AM, Michael S. Tsirkin wrote:
> > On Tue, Nov 26, 2013 at 06:24:53AM +1000, Richard Henderson wrote:
> >> On 11/25/2013 09:48 PM, Michael S. Tsirkin wrote:
> >>> g_string_vprintf was only introduced in 2.24 so switch to vsnprintf
> >>> instead.  A bit uglier but name size is fixed at 4 bytes here so it's
> >>> easy.
> >>
> >> You list 2.24 here,
> >>
> >>> -    GString *s = g_string_new("");
> >>> +    /* It would be nicer to use g_string_vprintf but it's only there in 
> >>> 2.22 */
> >>
> >> ... 2.22 here.
> >>
> >> But 
> >> https://developer.gnome.org/glib/2.28/glib-Strings.html#g-string-vprintf
> >>
> >> says "since 2.14".
> >>
> >>> +    char s[] = "XXXX";
> >>
> >> char s[5];
> >>
> >> Initializing it is a waste of time.
> >>
> >>
> >> r~
> > 
> > It's sets the length in a nice way.
> > 
> 
> Then do something like
> 
>   char s[sizeof("XXXX")];
> 
> so that the actual initialization doesn't happen.
> 
> 
> r~

Why? As an optimization?
I'm not quite sure this doesn't mean we are using VLA which I'd rather not.
Would need to look at language spec ... simple initialization is shorter
and more obviously correct.