Re: [PATCH 05/12] compiler.h: drop __printf__ macro MinGW/glib workaround

[Daniel P . Berrangé]

On Thu, Feb 24, 2022 at 08:14:47PM +0000, Peter Maydell wrote:
> On Thu, 24 Feb 2022 at 19:50, Marc-André Lureau
> <marcandre.lureau@gmail.com> wrote:
> > On Thu, Feb 24, 2022 at 11:23 PM Peter Maydell <peter.maydell@linaro.org> 
> > wrote:
> >> You're probably building with a newer glib, and possibly also
> >> a newer mingw.
> >>
> >> I've cc'd Stefan Weil who might know whether we can drop this
> >> workaround as far as the mingw part is concerned.
> >
> >
> > Probably safer to keep it until we bump glib dependency to >=2.58.
> >
> > I would move it to glib-compat.h though, and leave a note there, as it is 
> > (or should be ) an old glib specific workaround.
> 
> We can only move it to glib-compat if we confirm that only the
> glib-related part of the workaround is still relevant and the
> mingw side is now no longer needed, though.

We know glib uses the GNU printf semantics for all its APIs.

We know QEMU code will use the GNU printf annotation for all its
APIs where it knows it has GNU printf, due to delegating to
GLib.

For 3rd party libraries, we can have no confidence about whether
they expect GNU or native printf format, unless we're doing
something to override the printf family of functions at link
time. IIRC, we're not doing that, so we can't assume 3rd party
stuff expects GNU format, and so the sooner we get rid of
the #define __printf__ __gnu_printf__ the better IMHO. The
proof of course would be to see a CI test run with the define
removed proving that no code we call relies on it.

We could even set our min GLib version to something newer
just for Win32, on the basis that mingw in Fedora and msys2
both ship new enough versions, and cygwin is already outdated
and so already needs to have its glib upgraded to remain
compatible with QEMU.

With regards,
Daniel
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