how can use get_option() in project()

[Freed-Wu]

project(
  'test',
  ['c'],
  version: get_option('version'),
)

Cannot work, it said version is unknown.

[eli-schwartz]

Why would "version" ever be a choice that the user building the project is making?

[Freed-Wu]

There just is an example, for other things (langauge, ...) they also cannot use get_option()

And for version, I figure out one situation:

In github workflow, there is an enviroment variable named $GITHUB_REF_NAME contains git tag information. We can use meson setup build -Dversion=$GITHUB_REF_NAME to pass version to meson, to make sure we can build finial project with the version determined from git tag.

[eli-schwartz]

But what is the use case?

Version makes no sense -- using meson setup build -Dversion=$GITHUB_REF_NAME in GitHub actions means you can't build the project outside of GitHub actions with working project information.

Language isn't a good use case either -- if you have conditionally used languages, please use add_languages with the required kwarg at the point where you are using other languages (maybe behind an OS conditional, maybe behind a feature option).

[Freed-Wu]

you can't build the project outside of GitHub actions with working project information.

out of github action, we can meson setup build use default value of meson.options.

Language isn't a good use case either

Just an example 😄 required should be better choice for this situtation.

[eli-schwartz]

Just don't do broken stuff that depends on GitHub actions?

If using a default value in meson.options is okay then simply put that same value in meson.build instead, and don't bother with GITHUB_REF_NAME no matter what.

If what you actually want is to determine the version based on the state of the git repo, you should be using git describe anyway.