🔥 Drop support for Python 3.7

[kinuax]

CPython and click already dropped support for Python 3.7. I would propose to proceed accordingly here in order to benefit from:

• reducing the CI tests
• utilizing improved types without branching
• making available the syntax provided by 3.8:
  • assignment expressions
  • positional-only arguments
  • f-strings with =

3.7 occurrences are updated. Literal related branching is cleaned. _typing is updated and simplified. All local tests pass on 3.8-3.12 and Linux.

Context: #828

[kinuax]

CI tests pass.

[svlandeg]

Thanks for the very thorough PR!

I'll have to ask @tiangolo what the term is he wants to drop Python 3.7 by.

Note - I'm also maintaining spaCy and there we just bumped the Typer pin to allow any v0.x. If Typer drops Python 3.7 which spaCy v3 still supports, we'll have to again restrict the upper bound for Typer there. And I can imagine spaCy not being the only repo that would run into this.

I think we'll want to drop 3.7 at some point, it's just a question of when :-)

[kinuax]

@svlandeg, thanks for reviewing the PR and for sharing your thoughts. 👍

I understand the concern about avoiding breaking dependent libraries.

Besides, I rechecked the click repo and I would like to inform (and also correct previous statements) that, although old, the specific change that drops 3.7 is not released yet (it was merged in main branch right after the latest release 8.1.7).
This means that, in my opinion, the consideration of dropping support in Typer would happen, at least, after a new click release takes place. So this PR is just a prep for that moment.

[tiangolo]

Thanks @kinuax! I want to keep support for Python 3.7 for a while. It's currently not being a problem (yet) so I prefer to delay this a bit.

I would also want to have some features and fixes in before dropping support, so that people stuck in 3.7 can benefit from them too.

[kinuax]

@tiangolo, all right, I understand, thanks for clarifying.

[kinuax]

Merge conflicts are solved and tests are passing. Ready to be reviewed.

[kinuax]

Latest merge conflicts are solved.

[kinuax]

Recent Click release 8.2.0 drops support for Python 3.7.

[svlandeg]

All our other repos (asyncer, fastapi, sqlmodel) have now also dropped support for Python 3.7, as has Click. So I think we should go ahead and merge this to avoid issues on other PRs.

@kinuax: thanks for your continued work on this! Much appreciated 🙏

[github-actions]

📝 Docs preview for commit f91947a at: https://1e602f84.typertiangolo.pages.dev

[tiangolo]

The time has come, let's do this! 🚀 🔥

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I'm not marking it as a breaking change because package installers like pip and any others wouldn't accidentally install an unsupported version, so even if we make new releases with things unsupported in previous versions of Python, those won't be installed in those versions because the installer checks for Python version compatibility.