Re: [PATCH 02/28] glib-compat: Introduce g_memdup2() wrapper

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Sep 03, 2021 at 02:51:21PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> That was most probably already discussed, so sorry my question:
> 
> Why we can't just do
> 
> #if ! GLIB_CHECK_VERSION(2, 68, 0)
> static inline gpointer g_memdup2(gconstpointer mem, gsize byte_size)
> {
>     gpointer new_mem;
> 
>     if (mem && byte_size != 0) {
>         new_mem = g_malloc(byte_size);
>         memcpy(new_mem, mem, byte_size);
>     } else {
>         new_mem = NULL;
>     }
> 
>     return new_mem;
> }
> #endif
> 
> ?

This doesn't play with GLIB_VERSION_MAX_ALLOWED - any use of
g_memdup2 will trigger compile warnings since we're using an
API that only exists in a glib version newer than our declared
baseline.

The inline wrapper  + macro is a trick that lets us backport
new features, while avoiding the compile warnings.

This is documented in the include/glib-compat.h file that Philippe
is modifying.

Regards,
Daniel
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