[Debian-med-packaging] Bug#971408: simde: FTBFS when dpkg-buildflags passes -ffile-prefix-map

[Vagrant Cascadian]

On 2020-11-21, Michael R. Crusoe wrote:
> On Sat, 03 Oct 2020 09:38:03 -0700 Vagrant Cascadian
> <vagrant at reproducible-builds.org> wrote:
>> On 2020-09-29, Vagrant Cascadian wrote:
>> > When run with DEB_BUILD_OPTIONS=reproducible=+fixfilepath, simde FTBFS:
>> >
>> > clang: error: unknown argument: '-ffile-prefix-map=/<<PKGBUILDDIR>>=.'
>> >
>> > This is because clang 10 is the first version to support
>> > -ffile-prefix-map, and simde is building with the default clang version
>> > 9.
>> >
>> > The attached patch updates to clang-10 to fix this issue.
>>
>> Though clang 11 might become the default for bullseye, in which case
>> this would be a needless change; I haven't tested if simde builds fine
>> with clang 11.
>
> Thank you Vagrant for reporting this issue and your patch.

Thanks for the reply!


> SIMDe is a header-only library, the compilation is just to test the
> library against the default GCC & clang versions in Debian. I would
> prefer to keep testing the default versions, to get ahead of any bugs
> that might appear.

Yes, that makes perfect sense.

Another option might be to check the version of clang and strip the
unsupported -ffile-prefix-map=BUILDPATH=. argument if present when
running a version of clang that does not support -ffile-prefix-map
(e.g. 9 or less). Then it would "just work" whenever the updated clang
version lands, while keep working with older clang versions until
then. No idea how complicated that might be to actually implement, but
would solve all the corner cases nicely. :)


> I guess testing for all versions of clang and gcc in Debian could be
> done as part of the package building and autopkgtest.

Sure.


> So I'm leaning towards adding the other fix of disabling setting
> DEB_BUILD_MAINT_OPTIONS=reproducible=-fixfilepath+fixdebugpath
>
> What do you think?

If you do go that route, I would suggest a minor update to my patch:

  DEB_BUILD_MAINT_OPTIONS=reproducible=-fixfilepath

The dpkg patch I proposed should avoid disabling fixdebugpath without
having to specifically re-enable it. Based on the conversation on:

  https://bugs.debian.org/974087

It looks like fixfilepath may get enabled by default in dpkg "soon".


Thanks for taking a look at all the options!


FWIW, note that I only managed to see this reply because of the
accidental closing of this bug; normally you need to CC
NNN-submitter at bugs.debian.org or CC the submitter's email address
directly in order for them to see the reply. Luckily I saw it all the
same. :)


live well,
  vagrant
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