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Re: [Qemu-trivial] [Qemu-devel] [PATCH] fix MinGW compilation when --ena

From: Stefan Weil
Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH] fix MinGW compilation when --enable-vnc-jpeg is specified
Date: Sun, 26 Jun 2011 22:03:11 +0200
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20110424 Thunderbird/3.1.10

Am 26.06.2011 20:06, schrieb Blue Swirl:
On Thu, Jun 23, 2011 at 6:05 PM, Stefan Weil<address@hidden>  wrote:
Am 23.06.2011 15:52, schrieb Stefan Hajnoczi:
On Sat, Jun 18, 2011 at 10:35:57AM +0200, Stefan Weil wrote:
Am 18.06.2011 07:13, schrieb Roy Tam:
This patch fix conflicting types for 'INT32' in basetsd.h in including
qemu-common.h first.

Sign-off-by: Roy Tam<address@hidden>
The conflicting declaration is in jmorecfg.h which is included from
Is the problem that the Windows headers included from qemu-common.h try
to #define INT32?

In that case I think an explicit fix is better:

#ifdef _WIN32
/* Include this before jpeglib.h for the INT32 definition */

...followed by png/jpeg includes...

Simply moving qemu-common.h provides no hints and is rather indirect.
Someone may move it back in the future.


INT32 is declared in basetsd.h which is included from windows.h
(with some indirections) which is included from qemu-os-win32.h
which is included from qemu-common.h.

INT32 is not a #define, but a data type (typedef) and very common
for w32 compilations. Windows programmers don't include basetsd.h
directly, but usually use windows.h.

Including qemu-common.h right at the beginning (after config.h where
needed) should be good practice for QEMU source code - like this:

#include "config.h"        /* optional */
#include "qemu-common.h"
#include <system includes> /* without those that are included from
qemu-common.h */
#include "other local includes"

As long as the maintainers don't accept patches which simply move
qemu-common.h, there is no danger. :-)

Of course a comment might be added. In most cases, I'm a great friend
of good comments, but in this special case, I don't think it is necessary.
It's a very special case of a typedef conflict caused by the mingw32
version of jpeglib (which is obviously rarely used), and it might be fixed
in a newer version of jpeglib (so the comment would be no longer
valid, and nobody would notice that).

We could also add a configure time check for this case for maximum
over engineering.

... which nobody wants. I suggest to apply the patch as it was sent
by Roy. Stefan H. suggests to add a comment before the patch is applied.

Both ways fix a (small) problem, so please just decide which
solution you prefer.

Stefan W.

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