`PANTS_VERSION` BUILD file symbol has no docs

[huonw]

Describe the bug

The PANTS_VERSION constant BUILD file symbol has no documentation:

PANTS_VERSION=2.22.0.dev3 pants help-all | jq .name_to_build_file_info.PANTS_VERSION

{
  "documentation": null,
  "is_target": false,
  "name": "PANTS_VERSION",
  "signature": null
}

Preferably we'd have:

• text for documentation
• some indication of what type value is, maybe like "signature": "Version"?

Pants version This seems to be the case since 2.18, up to the current latest version 2.22.0

OS Both

Additional info

• Will appear in online docs too after https://github.com/pantsbuild/pantsbuild.org/pull/216
• Relevant issues:
  • https://github.com/pantsbuild/pants/discussions/18117
  • https://github.com/pantsbuild/pants/issues/14832 (lots of discussion of contents in this one)

[huonw]

(I don't know if it's possible to use help to see info about this BUILD file symbol, due to the name collision with the [GLOBAL].pants_version option's env var)

[kaos]

(I don't know if it's possible to use help to see info about this BUILD file symbol, due to the name collision with the [GLOBAL].pants_version option's env var)

That's no issue, as we don't offer help for specific options, only on the subsystem level. Ooohh... but we do offer help for the env var names, which it does collide with. I forgot about that.

We'd need to add some scoping to help stuff.. so you could say pants env PANTS_VERSION --help or pants build PANTS_VERSION --help or some such.