Re: New packages: python3-breathe and python3-pybind11

Re: New packages: python3-breathe and python3-pybind11

[Chocimier]

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New comment by Chocimier on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-601341767

Comment:
Some cross compilation fail. Approach to [use cmake build-style](https://github.com/void-linux/void-packages/pull/18873#issuecomment-597118155) shown by @yopito and @gspe have better chance to work, because this build step is more complex.

Re: New packages: python3-breathe and python3-pybind11

[Chocimier]

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New comment by Chocimier on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-601343191

Comment:
python3-breathe builds fine without python-devel, and can be made noarch.

Re: New packages: python3-breathe and python3-pybind11

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-601358386

Comment:
> python3-breathe builds fine without python-devel, and can be made noarch.

The change has been made with the latest push.

Re: New packages: python3-breathe and python3-pybind11

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-601360449

Comment:
> Some cross compilation fail. Approach to [use cmake build-style](https://github.com/void-linux/void-packages/pull/18873#issuecomment-597118155) shown by @yopito and @gspe have better chance to work, because this build step is more complex.

There is no clean way around this. The problem is that the cmake modules invoke the Python interpreter to determine the size of a pointer on the target platform and compare it to the size of the pointer expected by the C++ compiler. The C++ (cross-) compiler returns a 4-byte pointer as expected. The Python interpreter is always native, and returns an 8-byte pointer. The test fails. We can never invoke the Python interpreter for the target arch because its binaries are not compatible with the host architecture.

The only useful thing the cmake build step does is prepare some configuration modules for cmake. I've just copied the relevant modules into `files/` and install them where they need to go in `post_install`. The modules do not appear to be architecture dependent and should be usable on all architectures supported by Void.

Re: New packages: python3-breathe and python3-pybind11

[Chocimier]

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New comment by Chocimier on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-601884870

Comment:
This forces pybind to be installed on all archs, but if pybind is used by other package, cross build will use incorrect interpreter again, right? I think we should give upstream this as another argument to use [FindPython](https://cmake.org/cmake/help/latest/module/FindPython.html). Then if package is useful without FindPythonLibsNew.cmake, remove it, otherwise reconsider why do we need header only library in repo at all.

Re: New packages: python3-breathe and python3-pybind11

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-602615384

Comment:
> This forces pybind to be installed on all archs, but if pybind is used by other package, cross build will use incorrect interpreter again, right? I think we should give upstream this as another argument to use [FindPython](https://cmake.org/cmake/help/latest/module/FindPython.html). Then if package is useful without FindPythonLibsNew.cmake, remove it, otherwise reconsider why do we need header only library in repo at all.

This is a good point, and one I had overlooked. I'll file a problem report upstream and see what shakes out. It would be nice to package pybind11 even though it's a header-only library. We want it for the same reason we want anything in the repo: easy of deployment and management.

Re: New packages: python3-breathe and python3-pybind11

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-602615384

Comment:
> This forces pybind to be installed on all archs, but if pybind is used by other package, cross build will use incorrect interpreter again, right? I think we should give upstream this as another argument to use [FindPython](https://cmake.org/cmake/help/latest/module/FindPython.html). Then if package is useful without FindPythonLibsNew.cmake, remove it, otherwise reconsider why do we need header only library in repo at all.

This is a good point, and one I had overlooked. I've [reported the problem upstream](https://github.com/pybind/pybind11/issues/2139) and will see what shakes out. It would be nice to package pybind11 even though it's a header-only library. We want it for the same reason we want anything in the repo: easy of deployment and management.

Re: New packages: python3-breathe and python3-pybind11

[ahesford]

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New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/20218#issuecomment-622208538

Comment:
pybind11 upstream is still debating the right way to support CMake modules compatible with cross-compilation environments as in Void. However, the CMake modules are not used by the pybind11 headers; they are offered to support tests and as a convenience to dependent projects. I've opted not to install the CMake modules to avoid potential breakage for any new projects that might want to leverage pybind11. If upstream figures out a suitable method, we can add the CMake modules in a later release.

In the meantime, the `python3-pybind11` module remains useful without the CMake modules and should be ready to go.