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Date: Tue, 10 Jul 2018 16:38:07 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [libvirt] [PULL 25/26] block: Remove deprecated
 -drive option serial
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To: Cornelia Huck <cohuck@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>, Peter Krempa <pkrempa@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Boris Fiuczynski <fiuczy@linux.ibm.com>, Qemu-block <qemu-block@nongnu.org>, Libvirt <libvir-list@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, Christian Borntraeger <borntraeger@de.ibm.com>

Am 10.07.2018 um 16:22 hat Cornelia Huck geschrieben:
> On Tue, 10 Jul 2018 07:59:15 +0200
> Markus Armbruster <armbru@redhat.com> wrote:
> 
> > In addition to actively pulling libvirt developers into review of
> > deprecation patches, we should pursue the idea to optionally let QEMU
> > fail on use of deprecated features, then have libvirt run its test suite
> > that way.
> 
> What about the following:
> 
> qemu_deprecated_option("old_option", "modern_option");
> 
> Which would then print (in normal operation)
> 
> "WARNING: 'old_option' is deprecated and will be removed; use 'modern_option' instead"
> 
> to the monitor (or to stderr? to both?).
> 
> If you start QEMU with a -no-deprecated-options switch, it would print
> 
> "ERROR: 'old_option' is deprecated and will be removed; use 'modern_option' instead"
> 
> and do an exit(1).
> 
> Would that be workable?

I think the function should just take a message:

    /* Works like error_report(), except for the WARNING/ERROR prefix
     * and exit(1) if -no-deprecated-options is set */
    void deprecation_report(const char *fmt, ...);

We don't necessarily deprecate only options, but we might also deprecate
monitor commands, specific options values (while keeping other values of
the same option) etc.

Kevin