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Re: [Qemu-devel] [PATCH] configure: mark qemu-ga VSS includes as system
From: |
Thomas Huth |
Subject: |
Re: [Qemu-devel] [PATCH] configure: mark qemu-ga VSS includes as system headers |
Date: |
Wed, 29 Jun 2016 10:27:26 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 |
On 29.06.2016 01:43, Michael Roth wrote:
> As of e4650c81, we do w32 builds with -Werror enabled. Unfortunately
> for cases where we enable VSS support in qemu-ga, we still have
> warnings generated by VSS includes that ship as part of the Microsoft
> VSS SDK.
>
> We can selectively address a number of these warnings using
>
> #pragma GCC diagnostic ignored ...
>
> but at least one of these:
>
> warning: ‘typedef’ was ignored in this declaration
>
> resulting from declarations of the form:
>
> typedef struct Blah { ... };
>
> does not provide a specific command-line/pragma option to disable
> warnings of the sort.
>
> To allow VSS builds to succeed, the next-best option is disabling
> these warnings on a per-file basis. pragmas like #pragma GCC
> system_header can be used to declare subsequent includes/declarations
> as being exempt from normal warnings, but this must be done within
> a header file.
>
> Since we don't control the VSS SDK, we'd need to rely on a
> intermediate header include to accomplish this, and
> since different objects in the VSS link target rely on different
> headers from the VSS SDK, this would become somewhat of a rat's nest
> (though not totally unmanageable).
>
> The next step up in granularity is just marking the entire VSS
> SDK include path as system headers via -isystem. This is a bit more
> heavy-handed, but since this SDK hasn't changed since 2005, there's
> likely little to be gained from selectively disabling warnings
> anyway, so we implement that approach here.
>
> This fixes the -Werror failures in both the configure test and the
> qga build due to shared reliance on $vss_win32_include. For the
> same reason, this also enforces a new dependency on -isystem support
> in the C/C++ compiler when building QGA with VSS enabled.
Did we ever support any non-GCC-based compiler for building QGA? I don't
think so, but in the worst case, we could later add a check whether the
compiler supports that parameter, too...
Anyway, I think your patch is a nice and clean way to deal with the
error messages from these headers, so:
Reviewed-by: Thomas Huth <address@hidden>