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From: Marcel Apfelbaum <marcel@redhat.com>
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Date: Thu, 10 Dec 2015 15:58:57 +0200
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Subject: Re: [Qemu-devel] [PATCH] Use error_fatal to simplify obvious fatal
 errors
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To: Markus Armbruster <armbru@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, qemu-arm@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Eduardo Habkost <ehabkost@redhat.com>

On 12/10/2015 02:34 PM, Markus Armbruster wrote:
> Marcel Apfelbaum <marcel.apfelbaum@gmail.com> writes:
>
>> On 12/10/2015 12:19 PM, Markus Armbruster wrote:
>>> Done with this admittedly crude Coccinelle semantic patch with manual
>>> burial of dead Error * variables squashed in:
>>>
>>>       @@
>>>       identifier FUN;
>>>       expression ERR, EC;
>>>       @@
>>>       -    FUN(&ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    FUN(&error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression ARG1, ERR, EC;
>>>       @@
>>>       -    FUN(ARG1, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    FUN(ARG1, &error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression ARG1, ARG2, ERR, EC;
>>>       @@
>>>       -    FUN(ARG1, ARG2, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    FUN(ARG1, ARG2, &error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression ARG1, ARG2, ARG3, ERR, EC;
>>>       @@
>>>       -    FUN(ARG1, ARG2, ARG3, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    FUN(ARG1, ARG2, ARG3, &error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression RET, ERR, EC;
>>>       @@
>>>       -    RET = FUN(&ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    RET = FUN(&error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression RET, ARG1, ERR, EC;
>>>       @@
>>>       -    RET = FUN(ARG1, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    RET = FUN(ARG1, &error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression RET, ARG1, ARG2, ERR, EC;
>>>       @@
>>>       -    RET = FUN(ARG1, ARG2, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    RET = FUN(ARG1, ARG2, &error_fatal);
>>>       @@
>>>       identifier FUN;
>>>       expression RET, ARG1, ARG2, ARG3, ERR, EC;
>>>       @@
>>>       -    RET = FUN(ARG1, ARG2, ARG3, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    RET = FUN(ARG1, ARG2, ARG3, &error_fatal);
>>>       @@
>>>       type T;
>>>       identifier FUN, RET;
>>>       expression ERR, EC;
>>>       @@
>>>       -    T RET = FUN(&ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    T RET = FUN(&error_fatal);
>>>       @@
>>>       type T;
>>>       identifier FUN, RET;
>>>       expression ARG1, ERR, EC;
>>>       @@
>>>       -    T RET = FUN(ARG1, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    T RET = FUN(ARG1, &error_fatal);
>>>       @@
>>>       type T;
>>>       identifier FUN, RET;
>>>       expression ARG1, ARG2, ERR, EC;
>>>       @@
>>>       -    T RET = FUN(ARG1, ARG2, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    T RET = FUN(ARG1, ARG2, &error_fatal);
>>>       @@
>>>       type T;
>>>       identifier FUN, RET;
>>>       expression ARG1, ARG2, ARG3, ERR, EC;
>>>       @@
>>>       -    T RET = FUN(ARG1, ARG2, ARG3, &ERR);
>>>       -    if (ERR != NULL) {
>>>       -        error_report_err(ERR);
>>>       -        exit(EC);
>>>       -    }
>>>       +    T RET = FUN(ARG1, ARG2, ARG3, &error_fatal);
>>>
>>
>> That's so cool!
>
> I'm afraid my sledgehammer approach to Coccinelle would make its
> inventors wince...
>
>> Isn't it the time to have our own Coccinelle directory
>> with scripts like this?
>
> Could do that if there's interest.
>
>>                          And to make them part of make check?
>
> I'm afraid that's not practical.  spatch solves a difficult problem, and
> takes its own sweet time to do it.

So it takes a long time to run. We could make it depend on an environment variable,
so at least the maintainers will run it :)

My point is, now we *could* have a guarantee that if anyone uses the old
way, we can catch it in time. It can be easily lost in the review process.

Anyway, it was only a thought.
Thanks,
Marcel


>
>> Is a pity to have them lost into a git comment...