Re: How can I enable option-checking from configure.ac after it being default-disabled?

[Eric Blake]

On 03/19/2012 09:32 AM, Ralf Corsepius wrote:
> On 03/19/2012 04:16 PM, Eric Blake wrote:
> 
>> Meta-question: Why are you disabling option-checking in the first place?
>>   It's contrary to GNU Coding Standards (the ability to disable option
>> checking is provided for non-GNU packages, but doesn't get as much
>> testing because GNU packages shouldn't be using it in the first place).

I think I used poor wording here; my intent was to state that the
ability to reject unknown options is something provided for non-GNU
packages, but that GNU packages should not be using the ability to
reject unknown options in the first place.

> 
> Option checking presumes all config-subdirs configure scripts are
> accepting the same set of configure-options.
> 
> This doesn't always apply and even less applies in cases of optional
> config-subdirs, esp. in cases when config-subdirs originate from
> different origins and are being treated as optional drop-in packages.

I think we're in violent agreement here.  GNU Coding Standards state
that packages must silently ignore unknown options.  Therefore, enabling
option checking (as a way to diagnose typos) is a violation of GCS.
Autoconf allows the ability to enable option-checking at the top level
for non-GNU packages, but the reason that you cannot re-enable option
checking after default-disablement is because autoconf cannot guarantee
that subdirs will behave correctly with option checking enabled.

Meanwhile, the mentioned hack of explicitly adding (and rejecting) just
the one commonly mis-spelled option, rather than all mis-spelled options
in general, can be argued to fit within the GCS - you are explicitly
recognizing a specific spelling and therefore it is no longer an unknown
option, while you continue to silently ignore all other unknown options.

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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