llvm dev - Jul 2019 - Python build dependency in LLVM and/or clang?

On Thu, 11 Jul 2019 at 21:44, Joerg Sonnenberger via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> That's what I said. The cmake based build system needs it. LIT is
> optional. It is entirely feasible to have a custom build system and no
> Python at all. It would be quite painful to break that.
To be explicit (and correct me if I misstate facts), NetBSD wants to
build Clang with minimal dependencies because it's the system
compiler. And so it completely replaces our build system with
something not far removed from a hard-coded set of build steps to
eliminate CMake/make/ninja (maybe you allow make?). Tests are not run
(at that stage?) since they do always require Python.

To be frank, I do not think we should compromise LLVM to support this
system. It's just not a realistic thing to impose on an external
project: NetBSD's footprint constraints are its choice, and it should
bear the burden of supporting them.

Personally, I support adding Python as a build dependency. Though I'd
be interested in seeing responses to Mehdi's comments.

Cheers.

Tim.

LLVM's dependency on Python to *build* is historical, and could actually be
removed. We use it for LLVMBuild, which was important back when we had autoconf
as a method of maintaining library dependency graphs between autoconf and CMake.
We could actually remove LLVMBuild and with it the python dependency. There was
even a few patches a few years back to do it.

See:

https://reviews.llvm.org/D28086 <https://reviews.llvm.org/D28086>
https://reviews.llvm.org/D28856 <https://reviews.llvm.org/D28856>
https://reviews.llvm.org/D28855 <https://reviews.llvm.org/D28855>

-Chris

> On Jul 11, 2019, at 1:53 PM, Tim Northover via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> On Thu, 11 Jul 2019 at 21:44, Joerg Sonnenberger via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> That's what I said. The cmake based build system needs it. LIT is
>> optional. It is entirely feasible to have a custom build system and no
>> Python at all. It would be quite painful to break that.
> 
> To be explicit (and correct me if I misstate facts), NetBSD wants to
> build Clang with minimal dependencies because it's the system
> compiler. And so it completely replaces our build system with
> something not far removed from a hard-coded set of build steps to
> eliminate CMake/make/ninja (maybe you allow make?). Tests are not run
> (at that stage?) since they do always require Python.
> 
> To be frank, I do not think we should compromise LLVM to support this
> system. It's just not a realistic thing to impose on an external
> project: NetBSD's footprint constraints are its choice, and it should
> bear the burden of supporting them.
> 
> Personally, I support adding Python as a build dependency. Though I'd
> be interested in seeing responses to Mehdi's comments.
> 
> Cheers.
> 
> Tim.
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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This would be lovely.

                   -David

Chris Bieneman via llvm-dev <llvm-dev at lists.llvm.org> writes:
> LLVM's dependency on Python to *build* is historical, and could
actually be removed. We use it for LLVMBuild, which was important back when we
had autoconf as
> a method of maintaining library dependency graphs between autoconf and
CMake. We could actually remove LLVMBuild and with it the python dependency.
There
> was even a few patches a few years back to do it.
>
> See:
>
> https://reviews.llvm.org/D28086https://reviews.llvm.org/D28856
> https://reviews.llvm.org/D28855
>
> -Chris
>
>  On Jul 11, 2019, at 1:53 PM, Tim Northover via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>
>  On Thu, 11 Jul 2019 at 21:44, Joerg Sonnenberger via llvm-dev
>  <llvm-dev at lists.llvm.org> wrote:
>
>  That's what I said. The cmake based build system needs it. LIT is
>  optional. It is entirely feasible to have a custom build system and no
>  Python at all. It would be quite painful to break that.
>
>  To be explicit (and correct me if I misstate facts), NetBSD wants to
>  build Clang with minimal dependencies because it's the system
>  compiler. And so it completely replaces our build system with
>  something not far removed from a hard-coded set of build steps to
>  eliminate CMake/make/ninja (maybe you allow make?). Tests are not run
>  (at that stage?) since they do always require Python.
>
>  To be frank, I do not think we should compromise LLVM to support this
>  system. It's just not a realistic thing to impose on an external
>  project: NetBSD's footprint constraints are its choice, and it should
>  bear the burden of supporting them.
>
>  Personally, I support adding Python as a build dependency. Though I'd
>  be interested in seeing responses to Mehdi's comments.
>
>  Cheers.
>
>  Tim.
>  _______________________________________________
>  LLVM Developers mailing list
>  llvm-dev at lists.llvm.org
>  https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
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