add --version option to pybind11-config

[eli-schwartz]

Description

Without this, it's impossible to get feature parity between detection mechanisms. Both the pkg-config file and the cmake config set their versions, but the python probe script didn't provide an option for this.

So you could print the compiler flags for using it, but you could not check what you got.

Suggested changelog entry:

`python3 -m pybind11` gained a `--version` option (prints the version and exits), for feature parity between detection mechanisms.

[henryiii]

Didn't realize we didn't already have this!

What about about a -v shortcut? Not as important as -h, as it sometimes is a verbosity flag. Maybe not a good idea for a new flag, just a thought.

[eli-schwartz]

BTW, I need this because I'm adding a meson dependency('pybind11') that will support trying to run pybind11-config when neither pkg-config nor cmake are installed :) and this will allow us to display (and require) the version that was detected.

Didn't realize we didn't already have this!

Yeah, neither did I. :/

What about about a -v shortcut? Not as important as -h, as it sometimes is a verbosity flag. Maybe not a good idea for a new flag, just a thought.

I don't think this is necessary, no one currently depends on it and the main use case is for compatibility with classic Unix foobar-config shell scripts, which tend to have --version and not -v.

They also tend to use --cflags instead of --includes, but that is not so important, some of them also use --showme:compile or --cppflags and anyways that gets manually coded per meson dependency class.

[rwgk]

Could you please add help="Prints version and exits."

(This is almost straight from the argparse docs for actionversion, but I didn't know, and had to look it up.)

[eli-schwartz]

For context, I lazily didn't bother because the argparse default is to autogenerate help text for you: "show program's version number and exit"

However I'm more than happy to make this explicit. I've tweaked your suggested wording to better fit in with the style of __main__.py which consistently uses imperative mood, so "Prints" -> "Print".

[henryiii]

I'm fine with sticking with --version only.

[rwgk]

@henryiii I added a Suggested changelog entry to the PR description, based on my rather superficial understanding, hoping it's a better start than nothing.

[eli-schwartz]

Thanks.

For documentation purposes, when I refer to this fix -- should I write that the fix will be in pybind11 2.10.4 or 2.11.0? I'm assuming probably the former?

[henryiii]

Related: do you have an example of the best way to use pybind11 & meson together (probably in the context of meson-python)?

A quick search got me to mesonbuild/meson#4677 (comment). I'm guessing this will be nicer with the dependency('pybind11')? That's something that has to be added to meson?

2.10.4 depends on if we have enough to make it worth backporting before 2.11. Don't think we are moving very quickly towards 2.11, though, so I'd say it's possible there will be a 2.10.4. I'll let know know if I know more. (If there is a 2.10.4, this should be in it)

[eli-schwartz]

Yes, that has to be added to meson because foobar-config --includes style scripts don't get native handling otherwise.

The idea is that people should be able to just do this:

dependency('pybind11')

and that will most likely find the pybind11-config installed to $PATH (including to the $PATH of a pip build isolation environment). Although if the global version is installed, it may find the pkg-config or cmake file instead.

[henryiii]

Does the meson.build file in https://github.com/scikit-hep/cookie/pull/124/files look fine? I'm assuming the stuff in the middle of it can become dependency('pybind11') later. I'm not sure if there's a better way to copy the Python files over - the current listing of each file is highly prone to break when users add a file to the Python part of the package.

[eli-schwartz]

I left a comment there.

[henryiii]

There will be a 2.10.4, it's nearly ready except for #4301.

[henryiii]

Released 2.10.4.