[Pixman] [PATCH] configure: add options to disable demos and tests

[Oded Gabbay]

On Wed, Jan 20, 2016 at 8:35 PM, Bill Spitzak <spitzak at gmail.com> wrote:
> The ability to disabling everything except the library itself seems like a
> good idea.
>
> Make sure "make test" fails if tests are disabled.
>
> I do think it would be nice to actually patch the tests so they compile on
> these platforms.
>
> On Wed, Jan 20, 2016 at 1:13 AM, Thomas Petazzoni
> <thomas.petazzoni at free-electrons.com> wrote:
>>
>> Hello,
>>
>> On Wed, 20 Jan 2016 09:27:46 +0200, Siarhei Siamashka wrote:
>>
>> > Thanks for this patch. Though if building (and using) pixman on
>> > such platforms is wanted, then a much better solution would be to
>> > update the problematic tests and make them compile. Skipping some
>> > sub-tests is better than having no tests at all. I also remember
>> > your patch for FE_DIVBYZERO from a few months ago:
>> >
>> >
>> > http://lists.freedesktop.org/archives/pixman/2015-September/004019.html
>> >
>> > Is it still the same Microblaze or Nios2 architecture that is causing
>> > problems for you?
>>
>> Yes, it is. Other architectures might be affected because the <fenv.h>
>> implementation in uClibc is not complete for all architectures.
>>
>> > While adding new configure options just adds functionality and
>> > preserves the existing behavior, I don't feel very happy about
>> > the fact that this provides an easy way to ignore problems instead
>> > of fixing them. It would be really great is somebody tried to run
>> > the pixman test suite ("make check") on these architectures at
>> > least once.
>> >
>> > Encountering compiler bugs is unfortunately a regular occurrence
>> > for pixman. For example, not so long ago, GCC 4.9 miscompiled
>> > pixman on ARM (fortunately, the broken code was in the test suite
>> > itself and not in the pixman library):
>> >
>> >     https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64172
>> >
>> > And even just a few days ago, pixman was one of the victims during
>> > a GCC 6 snapshot test (an easy to notice ICE during a distro test
>> > rebuild):
>> >
>> >     https://gcc.gnu.org/ml/gcc/2016-01/msg00101.html
>> >     https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66856
>> >
>> > What I'm trying to say is that there had been many compiler bugs
>> > affecting pixman during the last few years. Now you are dealing
>> > with uncommon architectures, and the compilers there are probably
>> > even less mature than GCC on x86 / arm / powerpc.
>>
>> I agree, but those options also allow to skip building things that
>> won't be used, even if they actually build properly. On ARM, x86,
>> PowerPC and other "mainstream" architectures, the demos and tests build
>> fine, but they are not used at all by Buildroot, so it's just spending
>> time building things that aren't necessary.
>>
>> So even if those tests and demos were building for all architectures,
>> it would still be useful to have a way to *not* build them.
>>
>> But I'll have a look at re-enabling the building of the pixman tests in
>> Buildroot. Now that the FE_* things are disabled in the tests when not
>> available (after commit 4297e9058d252cac653723fe0b1bee559fbac3a4).
>>
>> Thanks!
>>
>> Thomas
>> --
>> Thomas Petazzoni, CTO, Free Electrons
>> Embedded Linux, Kernel and Android engineering
>> http://free-electrons.com
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>> Pixman at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/pixman
>
>
>
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Siarhei,

I agree with you in principal, but the reality is different.
When I worked on embedded devices and cross-compiling rpm packages, I
often had hard times with packages that didn't allow to disable the
tests. That is because you don't want the package building process to
run the tests on the host machine, as it will fail because the library
is built for target machine. In addition, sometimes you wanted to
minimize the size of the library to minimum due to space constraints,
and tests/demos are the first candidate for that.

So for libraries that gave the option to disable the tests, the
solution was easy. For other libraries I had to patch the configure
script / makefiles and curse the library developers ;)

Therefore, I believe there is a real justification for this. Although
it can be "abused" for skipping the tests, there are real world
use-cases for it.

Oded