Rollup of 5 pull requests #107636
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Rollup of 5 pull requests #107636
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Sometimes the parser needs to desugar a doc comment into `#[doc = r"foo"]`. Currently it does this in a hacky way: by pushing a "fake" new frame (one without a delimiter) onto the `TokenCursor` stack. This commit changes things so that the token stream itself is modified in place. The nice thing about this is that it means `TokenCursorFrame::delim_sp` is now only `None` for the outermost frame.
The motivation here is to eliminate the `Option<(Delimiter, DelimSpan)>`, which is `None` for the outermost token stream and `Some` for all other token streams. We are already treating the innermost frame specially -- this is the `frame` vs `stack` distinction in `TokenCursor`. We can push that further so that `frame` only contains the cursor, and `stack` elements contain the delimiters for their children. When we are in the outermost token stream `stack` is empty, so there are no stored delimiters, which is what we want because the outermost token stream *has* no delimiters. This change also shrinks `TokenCursor`, which shrinks `Parser` and `LazyAttrTokenStreamImpl`, which is nice.
This makes it clear they return token trees, and makes for a nice comparison against `TokenCursor` which returns tokens.
Autotrait bounds on dyn-safe trait methods This PR is a successor to rust-lang#106604 implementing the approach encouraged by rust-lang#106604 (comment). **I propose making it legal to use autotraits as trait bounds on the `Self` type of trait methods in a trait object.** rust-lang#51443 (comment) justifies why this use case is particularly important in the context of the async-trait crate. ```rust #![feature(auto_traits)] #![deny(where_clauses_object_safety)] auto trait AutoTrait {} trait MyTrait { fn f(&self) where Self: AutoTrait; } fn main() { let _: &dyn MyTrait; } ``` Previously this would fail with: ```console error: the trait `MyTrait` cannot be made into an object --> src/main.rs:7:8 | 7 | fn f(&self) where Self: AutoTrait; | ^ | = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue rust-lang#51443 <rust-lang#51443> note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety> --> src/main.rs:7:8 | 6 | trait MyTrait { | ------- this trait cannot be made into an object... 7 | fn f(&self) where Self: AutoTrait; | ^ ...because method `f` references the `Self` type in its `where` clause = help: consider moving `f` to another trait ``` In order for this to be sound without hitting rust-lang#50781, **I further propose that we disallow handwritten autotrait impls that apply to trait objects.** Both of the following were previously allowed (_on nightly_) and no longer allowed in my proposal: ```rust auto trait AutoTrait {} trait MyTrait {} impl AutoTrait for dyn MyTrait {} // NOT ALLOWED impl<T: ?Sized> AutoTrait for T {} // NOT ALLOWED ``` (`impl<T> AutoTrait for T {}` remains allowed.) After this change, traits with a default impl are implemented for a trait object **if and only if** the autotrait is one of the trait object's trait bounds (or a supertrait of a bound). In other words `dyn Trait + AutoTrait` always implements AutoTrait while `dyn Trait` never implements AutoTrait. Fixes dtolnay/async-trait#228. r? `@lcnr`
…=compiler-errors Add candidates for DiscriminantKind builtin Part of rust-lang#107379
…dex, r=lcnr Emit warnings on unused parens in index expressions Fixes: rust-lang#96606. I am not sure what the best term for "index expression" is. Is there a better term we could use?
…=petrochenkov Improve `TokenCursor`. Some small improvements, for things that were bugging me. Best reviewed one commit at a time. r? `@petrochenkov`
…, r=Nilstrieb Fix suggestion for coercing Option<&String> to Option<&str> Fixes rust-lang#107604 This also makes the diagnostic `MachineApplicable`, and runs `rustfix` to check we're not producing incorrect code. `@rustbot` label +A-diagnostics
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@bors r+ rollup=never p=5 |
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Successful merges:
TokenCursor. #107544 (ImproveTokenCursor.)Failed merges:
r? @ghost
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