Re: [Xen-devel] [PATCH v2 1/5] Remove hardcoded strict -Werror checking

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.12.16 at 18:30, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 29/12/2016 17:10, George Dunlap wrote:
>> On Tue, Dec 27, 2016 at 5:07 PM, Andrew Cooper
>> <andrew.cooper3@xxxxxxxxxx> wrote:
>>> On 27/12/16 15:53, Jan Beulich wrote:
>>>>>>> "Jan Beulich" <jbeulich@xxxxxxxx> 12/27/16 4:42 PM >>>
>>>>>>> Alistair Francis <alistair.francis@xxxxxxxxxx> 12/22/16 8:14 PM >>>
>>>>>> Everyone seems fairly open to an override. Is a environment variable,
>>>>>> which if set will disable Werror acceptable? Something like NO_ERROR=Y
>>>>>> which will result in no -Werror being appended.
>>>>> I dislike environment variables for such purposes, and would prefer
>>>>> requiring
>>>>> such to be added as make options. If it was an environment variable, it
>>>>> should start with XEN_. And its name should fully reflect the purpose,
>>>>> i.e. I
>>>>> shouldn't have to guess what kinds of errors would be suppressed. Perhaps
>>>>> WARN_NO_ERROR?
>>>> That said, I'm not sure everyone agreed on putting an override in place. I
>>>> think
>>>> Andrew had made it quite clear that there is a reason for -Werror to be in
>>>> use,
>>>> and we shouldn't encourage people weakening code by tolerating warnings
>>>> (even if for the purpose of upstream integration no warnings will be
>>>> permitted
>>>> anyway, due to -Werror remaining the default).
>>>
>>> For development, -Werror should remain the default.
>>>
>>> For downstream integration, an ability to override -Werror is useful for
>>> distros, especially in cases of using a newer compiler than the code was
>>> ever developed against.
>>>
>>> However, it should definitely be the case that a positive choice needs to be
>>> taken to disable -Werror, which should hopefully make people thing twice
>>> about doing so.
>> Wouldn't it make more sense to disable -Werror for the release?
> 
> -1.  This is not a sensible suggestion IMO.
> 
> The reason for switching off debugging for a release is because there is
> a runtime overhead of the debugging, and we don't provide security
> support in case the ASSERT()s are a little too aggressive.
> 
> The reason behind using -Werror doesn't change at the point of a
> release.  A warning on a release branch is just as important to fix as a
> warning on master.

The more that, with changed optimization settings, warnings
occasionally change too (potentially pointing out so far overlooked
issues). If _all_ our downstreams participated in at least RC testing,
the whole situation might be a little different, but without that I
think we should rather hope for them to report issues with compiler
versions no-one of us tried to build with.

Jan


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