rust/compiler/rustc_trait_selection
Matthias Krüger 862a17cd17
Rollup merge of #135639 - lqd:trivial-builtin-impls, r=lcnr
new solver: prefer trivial builtin impls

As discussed [on zulip](https://rust-lang.zulipchat.com/#narrow/channel/364551-t-types.2Ftrait-system-refactor/topic/needs_help.3A.20trivial.20builtin.20impls), this PR:
- adds a new `BuiltinImplSource::Trivial` source, and marks the `Sized` builtin impls as trivial
- prefers these trivial builtin impls in `merge_trait_candidates`

The comments can likely be wordsmithed a bit better, and I ~stole~ was inspired by the old solver ones. Let me know how you want them improved.

When enabling the new solver for tests, 3 UI tests now pass:
- `regions/issue-26448-1.rs` and its sibling `regions/issue-26448-2.rs` were rejected by the new solver but accepted by the old one
- and `issues/issue-42796.rs` where the old solver emitted some overflow errors in addition to the expected error

(For some reason one of these tests is run-pass, but I can take care of that another day)

r? lcnr
2025-01-18 09:11:06 +01:00
..
src Rollup merge of #135639 - lqd:trivial-builtin-impls, r=lcnr 2025-01-18 09:11:06 +01:00
Cargo.toml rename rustc_attr to rustc_attr_parsing and create rustc_attr_data_structures 2024-12-16 19:08:19 +01:00
messages.ftl mir_transform: implement forced inlining 2025-01-10 18:37:54 +00:00