Tracking Issue for `min_const_generics`

[lcnr]

This is a tracking issue for the minimal usable subset of RFC 2000 (rust-lang/rfcs#2000).
The feature gate for the issue is #![feature(min_const_generics)].

See rust-lang/lang-team#37 for more details.

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also uses as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

Steps

• Fix const-generics-blocking issues.
• Fix const-generics-bad-diagnostics issues.
• Add many more min_const_generics tests.
• const wf (generic params in associated consts)
• Adjust documentation (see instructions on rustc-dev-guide)
• Stabilization PR (see instructions on rustc-dev-guide)

Completed:

• should we keep allowing things like [u8; std::mem::size_of::<*mut T>()] here (cc make ConstEvaluatable more strict #74595)
• how to deal with ConstKind::Unevaluated and incorrect inference cycles (cc fix unification of const variables #74040)

Implementation history

• based of Tracking issue for const generics (RFC 2000) #44580
• split into a separate feature gate in Implement the min_const_generics feature gate #74877

[alex]

👋 I'm trying to understand the limitations of min_const_generics. Is it expected that https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=59cca2f3891e9fa921afdcbcda9f2588 compiles ok without min_const_generics, but fails with it?

[lcnr]

😐 min_const_generics should not cause breaking changes, that's a bug. Opened #75486

We will most probably write a more detailed summary of what will be allowed with this feature in the near future, for now I can recommend the post by @withoutboats about this: https://without.boats/blog/shipping-const-generics/

In general, please note that a tracking issue is not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter.

Feel free to ping @lcnr (me) when opening a new issue concerning this feature.