Enforce that `dyn*` coercions are actually pointer-sized
Implement a perma-unstable, rudimentary `PointerSized` trait to enforce `dyn*` casts are `usize`-sized for now, at least to prevent ICEs and weird codegen issues from cropping up after monomorphization since currently we enforce *nothing*.
This probably can/should be removed in favor of a more sophisticated trait for handling `dyn*` conversions when we decide on one, but I just want to get something up for discussion and experimentation for now.
r? ```@eholk``` cc ```@tmandry``` (though feel free to claim/reassign)
Fixes#102141Fixes#102173
When doing the optimized implementation of getting the discriminant, the
arithmetic needs to be done in the tag type so wrapping behavior works
correctly.
Fixes#104519
Rollup of 8 pull requests
Successful merges:
- #101162 (Migrate rustc_resolve to use SessionDiagnostic, part # 1)
- #103386 (Don't allow `CoerceUnsized` into `dyn*` (except for trait upcasting))
- #103405 (Detect incorrect chaining of if and if let conditions and recover)
- #103594 (Fix non-associativity of `Instant` math on `aarch64-apple-darwin` targets)
- #104006 (Add variant_name function to `LangItem`)
- #104494 (Migrate GUI test to use functions)
- #104516 (rustdoc: clean up sidebar width CSS)
- #104550 (fix a typo)
Failed merges:
- #104554 (Use `ErrorGuaranteed::unchecked_claim_error_was_emitted` less)
r? `@ghost`
`@rustbot` modify labels: rollup
`_` might confuse people into believing that the type isn't known,
while `...` is not used anywhere else for types and is not valid
syntax, making it more likely to convey the right understanding.
Add variant_name function to `LangItem`
Clippy has an internal lint that checks for the usage of hardcoded def paths and suggests to replace them with a lang or diagnostic item, if possible. This was implemented with a hack, by getting all the variants of the `LangItem` enum and then index into it with the position of the `LangItem` in the `items` list. This is no longer possible, because the `items` list can't be accessed anymore.
Follow up to #103603
cc `@camsteffen`
r? `@oli-obk`
This is blocking the sync between Clippy and Rust. I'm not sure if this is the best solution here, or if I should add a method `items()` to `LanguageItems` and keep the code in Clippy unchanged.
Don't allow `CoerceUnsized` into `dyn*` (except for trait upcasting)
This makes sure we don't accidentally allow coercions like `Box<T>` -> `Box<dyn* Trait>`, or in the case of this ICE, `&T` to `&dyn* Trait`. These coercions don't make sense, at least not via the `CoerceUnsized` trait.
Fixes#102172Fixes#102429
Readd the matches_macro diag item
This is now used by Clippy
r? `@compiler-errors`
This was removed in #104383. But in the meantime Clippy now makes use of it dac600e32f/clippy_lints/src/manual_is_ascii_check.rs (L153)
---
This is blocking the Clippy sync. (kinda. I could work around it, but I don't want to play ping-pong with this change.)
Check `dyn*` return type correctly
In `check_fn`, if the declared return type is `dyn Trait`, then we check the return type separately to produce better diagnostics, because this is never valid -- however, when `dyn*` was introduced, this check was never adjusted to only account for *unsized* `dyn Trait` and not *sized* `dyn* Trait`.
Fixes#104501
Convert predicates into Predicate in the Obligation constructor
instead of having almost all callers do that.
This reduces a bit of boilerplate, and also paves the way for my work towards https://github.com/rust-lang/compiler-team/issues/531 (as it makes it easier to accept both goals and clauses where right now it only accepts predicates).
