Introduce `X..`, `..X`, and `..=X` range patterns
Tracking issue: https://github.com/rust-lang/rust/issues/67264
Feature gate: `#![feature(half_open_range_patterns)]`
---------------------------
In this PR, we introduce range-from (`X..`), range-to (`..X`), and range-to-inclusive (`..=X`) patterns.
These correspond to the `RangeFrom`, `RangeTo`, and `RangeToInclusive` expression forms introduced with the same syntaxes. The correspondence is both syntactic and semantic (in the sense that e.g. a `X..` pattern matching on a scrutinee `s` holds exactly when `(X..).contains(&s)` holds).
---------------------------
Noteworthy:
- The compiler complexity added with this PR is around 10 lines (discounting new tests, which account for the large PR size).
- `...X` is accepted syntactically with the same meaning as `..=X`. This is done primarily to simplify and unify the implementation & spec. If-and-when we decide to make `X...Y` a hard error on a new edition, we can do the same for `...X` patterns as well.
- `X...` and `X..=` is rejected syntactically just like it is for the expression equivalents. We should perhaps make these into semantic restrictions (cc @petrochenkov).
- In HAIR, these half-open ranges are represented by inserting the max/min values for the approprate types. That is, `X..` where `X: u8` would become `X..=u8::MAX` in HAIR (note the `..=` since `RangeFrom` includes the end).
- Exhaustive integer / char matching does not (yet) allow for e.g. exhaustive matching on `0usize..` or `..5usize | 5..` (same idea for `isize`). This would be a substantially more invasive change, and could be added in some other PR.
- The issues with slice pattern syntax has been resolved as we decided to use `..` to mean a "rest-pattern" and `[xs @ ..]` to bind the rest to a name in a slice pattern.
- Like with https://github.com/rust-lang/rust/pull/35712, which provided `X..Y` range patterns, this is not yet backed up by an RFC. I'm providing this experimental implementation now to have something concrete to discuss. I would be happy to provide an RFC for this PR as well as for #35712 to finalize and confirm the ideas with the larger community.
Closes https://github.com/rust-lang/rfcs/issues/947.
---------------------------
r? @varkor cc @matthewjasper @oli-obk
I would recommend reviewing this (in particular HAIR-lowering and pattern parsing changes) with whitespace changes ignored.
self-profiling: Support recording query keys
This PR makes self-profiling able to record query keys. The implementation is not as efficient as it could be yet (all query keys except for `DefId`s cause string data to be duplicated) and the rendered strings could be nicer too. But the implementation is functional and introduces the basic framework for emitting per-query-invocation event data.
I tried to add proper documentation on how everything works. Let me know if more documentation is needed.
r? @wesleywiser
@Mark-Simulacrum, heads up: This updates `measureme` to 0.7.0 which means that `summarize` on perf.rlo needs to be update accordingly once this is merged.
Rollup of 6 pull requests
Successful merges:
- #66463 (Point at opaque and closure type definitions in type errors)
- #67501 (Reduce special treatment for zsts)
- #67820 (Parse the syntax described in RFC 2632)
- #67922 (rustc_ast_lowering: misc cleanup & rustc dep reductions)
- #68071 (Extend support of `_` in type parameters)
- #68073 (expect `fn` after `const unsafe` / `const extern`)
Failed merges:
r? @ghost
Extend support of `_` in type parameters
- Account for `impl Trait<_>`.
- Provide a reasonable `Span` for empty `Generics` in `impl`s.
- Account for `fn foo<_>(_: _) {}` to suggest `fn foo<T>(_: T) {}`.
- Fix#67995. Follow up to #67597.
rustc_ast_lowering: misc cleanup & rustc dep reductions
- The first two commits do some code simplification.
- The next three do some file splitting (getting `lib.rs` below the 3kloc tidy lint).
- The remaining commits reduce the number of `rustc::` imports. This works towards making lowering independent of the `rustc` crate.
r? @oli-obk cc @Zoxc
Parse the syntax described in RFC 2632
This adds support for both `impl const Trait for Ty` and `?const Trait` bound syntax from rust-lang/rfcs#2632 to the parser. For now, both modifiers end up in a newly-added `constness` field on `ast::TraitRef`, although this may change once the implementation is fleshed out.
I was planning on using `delay_span_bug` when this syntax is encountered during lowering, but I can't write `should-ice` UI tests. I emit a normal error instead, which causes duplicates when the feature gate is not enabled (see the `.stderr` files for the feature gate tests). Not sure what the desired approach is; Maybe just do nothing when the syntax is encountered with the feature gate is enabled?
@oli-obk I went with `const_trait_impl` and `const_trait_bound_opt_out` for the names of these features. Are these to your liking?
cc #67792#67794
r? @Centril
