rust/compiler/rustc_middle
bors bf62436bce Auto merge of #114602 - compiler-errors:rpit-outlives-sadness, r=oli-obk
Map RPIT duplicated lifetimes back to fn captured lifetimes

Use the [`lifetime_mapping`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir/hir/struct.OpaqueTy.html#structfield.lifetime_mapping) to map an RPIT's captured lifetimes back to the early- or late-bound lifetimes from its parent function. We may be going thru several layers of mapping, since opaques can be nested, so we introduce `TyCtxt::map_rpit_lifetime_to_fn_lifetime` to loop through several opaques worth of mapping, and handle turning it into a `ty::Region` as well.

We can then use this instead of the identity substs for RPITs in `check_opaque_meets_bounds` to address #114285.

We can then also use `map_rpit_lifetime_to_fn_lifetime` to properly install bidirectional-outlives predicates for both RPITs and RPITITs. This addresses #114601.

I based this on #114574, but I don't actually know how much of that PR we still need, so some code may be redundant now... 🤷

---

Fixes #114597
Fixes #114579
Fixes #114285

Also fixes #114601, since it turns out we had other bugs with RPITITs and their duplicated lifetime params 😅.

Supersedes #114574

r? `@oli-obk`
2023-08-08 13:03:10 +00:00
..
src Auto merge of #114602 - compiler-errors:rpit-outlives-sadness, r=oli-obk 2023-08-08 13:03:10 +00:00
Cargo.toml Replace in-tree rustc_apfloat with the new version of the crate 2023-07-26 10:20:15 -04:00
messages.ftl Don't attempt to compute layout of type referencing error 2023-07-27 18:24:08 +00:00
README.md

For more information about how rustc works, see the rustc dev guide.