manylinux_2_31_armv7l compiler too old

[mara004]

I noticed the Ubuntu-based manylinux_2_31_armv7l is - unfortunately - too old to build the project I'm dealing with.
Ubuntu Focal (20.04) repos do not provide the GN build system, and when I try to bootstrap it, the compiler appears to be too old for C++20. And the same probably applies for the project I want to build with GN.

Taking a look at https://github.com/mayeut/manylinux-ubuntu, it says there is also a manylinux_2_35 image (22.04-based), so I tried setting manylinux-armv7l-image = "manylinux_2_35" in pyproject.toml cibuildwheel config, but it fails.
Taking a quick look at the sources, I believe this image is just not registered in cibuildwheel yet?
Is there a chance to get it added, or any other way of using this newer image from the caller side?

Thanks!

[mara004]

Hmm, writing this up, I figured gcc 9 is just the default, and there might be a newer compiler available in Focal repos?
But https://packages.ubuntu.com/ only goes down to Jammy, so not sure how to look this up...

The manylinux-ubuntu Readme just says

• in order to achieve compatibility with "older" systems, you get an older toolchain:
  • gcc9 on Ubuntu 20.04 (manylinux_2_31 wheels compatible with Ubuntu 20.04+, Debian 11+)
  • gcc11 on Ubuntu 22.04 (manylinux_2_35 wheels compatible with Ubuntu 22.04+, Debian 12+)

[mara004]

Okay, yes, Focal does provide g++-10 and I managed to build GN by setting CXX=g++-10, though with a great deal of compiler warnings.
But the main project I'm trying to build (pdfium) still uses default gcc 9, which fails.
I can't seem to find a config variable to set the gcc version. I might be able to plug in a custom_toolchain, but I'm not sure it's worth the trouble...

[henryiii]

This is generally the problem with Ubuntu based distributions for something like manylinux. The Red Hat distributions have specially patched compilers available to target the older GLIBC. These compilers statically link just the new symbols into the binary.

So we are stuck with the compilers that came out with the old distribution, which are old, unless you build compilers yourself and then statically link your binaries to the stdlib.

[mayeut]

Taking a quick look at the sources, I believe this image is just not registered in cibuildwheel yet?
Is there a chance to get it added, or any other way of using this newer image from the caller side?

You can already use any docker image you want: https://cibuildwheel.pypa.io/en/stable/options/#linux-image
Only images maintained at https://github.com/pypa/manylinux are registered in cibuildwheel.
An example can be found (though for riscv64 rather than armv7l) that uses manylinux_2_35 there: https://github.com/scikit-build/cmake-python-distributions/blob/main/pyproject.toml#L108

[mara004]

Indeed, thank you! Sorry, I missed I could just set this to an image URL. 🤦‍♂️

Though perhaps it wouldn't harm to register this in cibuildwheel so the short form manylinux_2_35 could be used as well here?