Re: [Qemu-devel] [PATCH 3/7] qga: Clean up unnecessarily dirty casts

[Eric Blake <eblake@redhat.com>]

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On 06/22/2015 01:26 PM, Markus Armbruster wrote:
> qga_vss_fsfreeze() casts error_set_win32() from
> 
>     void (*)(Error **, int, ErrorClass, const char *, ...)
> 
> to
> 
>     void (*)(void **, int, int, const char *, ...)
> 
> The result is later called.  Since the two types are not compatible,
> the call is undefined behavior.  It works in practice anyway.

Better than some other horrid casts we do, like monitor.c playing fast
and loose with 'Monitor *' vs. 'FILE *' in hmp_info_mtree() and friends.
 But that's a cleanup for another series.

> 
> However, there's no real need for trickery here.  Clean it up as
> follows:
> 
> * Declare struct Error, and fix the first parameter.
> 
> * Switch to error_setg_win32().  This gets rid of the troublesome
>   ErrorClass parameter.  Requires converting error_setg_win32() from
>   macro to function, but that's trivially easy, because this is the
>   only user of error_set_win32().
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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