Re: python version confusion with cython (Re: math/py-scipy)

["David H. Gutteridge" <david%gutteridge.ca@localhost>]

On Thu, 12 Oct 2023 at 12:47:04 +0200, "Dr. Thomas Orgis" wrote:
> Am Thu, 12 Oct 2023 11:00:19 +0200
> schrieb "Dr. Thomas Orgis" <thomas.orgis%uni-hamburg.de@localhost>:
>
> > OK, I am trying to test this and stumble over something along
> >
> > https://github.com/scipy/scipy/issues/17808
> >
> > I don't have cython or cython3 in my pkgsrc prefix. I do have
> > $PREFIX/bin/cython-3.10 (and cythonize-3.10). We have cython handled
> > along with all usual python cruft with multiversion support.
>
> I tried to adapt some SUBST_SED that we already have for pythran, but
> cython is different, as it appears both as language and compiler name
> in meson.build.
>
> How does that build for anyone? Is a cython in /usr/bin found on Linux?
> I consistently get something along
>
> ===> Building for py310-scipy-1.11.3
> * Building wheel...
> + meson setup 
> /data/projekte/pkgsrc/work/math/py-scipy/work/scipy-1.11.3 
> /data/projekte/pkgsrc/work/math/py-scipy/work/scipy-1.11.3/.mesonpy-ps9ehs0i/build 
> -Dbuildtype=release -Db_ndebug=if-release -Db_vscrt=md 
> -Dblas=openblas_openmp -Dlapack=openblas_openmp 
> --native-file=/data/projekte/pkgsrc/work/math/py-scipy/work/scipy-1.11.3/.mesonpy-ps9ehs0i/build/meson-python-native-file.ini
> The Meson build system
> Version: 1.1.0
> Source dir: /data/projekte/pkgsrc/work/math/py-scipy/work/scipy-1.11.3
> Build dir: 
> /data/projekte/pkgsrc/work/math/py-scipy/work/scipy-1.11.3/.mesonpy-ps9ehs0i/build
> Build type: native build
> Project name: SciPy
> Project version: 1.11.3
> C compiler for the host machine: cc (gcc 11.4.0 "gcc (Ubuntu 
> 11.4.0-1ubuntu1~22.04) 11.4.0")
> C linker for the host machine: cc ld.bfd 2.38
> C++ compiler for the host machine: c++ (gcc 11.4.0 "g++ (Ubuntu 
> 11.4.0-1ubuntu1~22.04) 11.4.0")
> C++ linker for the host machine: c++ ld.bfd 2.38
>
> ../../meson.build:1:0: ERROR: Unknown compiler(s): [['cython'], 
> ['cython3']]
> The following exception(s) were encountered:
> Running `cython -V` gave "[Errno 2] No such file or directory: 
> 'cython'"
> Running `cython3 -V` gave "[Errno 2] No such file or directory: 
> 'cython3'"
>
> A full log can be found at 
> /data/projekte/pkgsrc/work/math/py-scipy/work/scipy-1.11.3/.mesonpy-ps9ehs0i/build/meson-logs/meson-log.txt
>
> ERROR Backend subprocess exited when trying to invoke build_wheel
> *** Error code 1
>
>
> Why not everyone?

Short answer: the version of Meson from pkgsrc you're using is too old.
Please update to at least meson-1.2.1nb3. This handles pkgsrc's idea of
versioned Cython. (Yes, there's a separate packaging bug at present
that py-scipy and py-pandas should both specify they need a newer
patched version of meson at minimum. That's a miss on my part, sorry.)

This has been discussed in a couple of email threads, e.g., see
http://mail-index.netbsd.org/tech-pkg/2023/09/29/msg028251.html

There are several possibilities to handle this differently. You touched
on one I didn't mention, using Cython as an unversioned tool.

Regards,

Dave