Tweak obligation error output
- Point at arguments or output when fn obligations come from them, or ident when they don't
- Point at `Sized` bound (fix#47990)
- When object unsafe trait uses itself in associated item suggest using `Self` (fix#66424, fix#33375, partially address #38376, cc #61525)
- Point at reason in object unsafe trait with `Self` in supertraits or `where`-clause (cc #40533, cc #68377)
- On implicit type parameter `Sized` obligations, suggest `?Sized` (fix#57744, fix#46683)
Step stage0 to bootstrap from 1.42
This also includes a commit which fixes the rustfmt downloading logic to redownload when the rustfmt channel changes, and bumps rustfmt to a more recent version.
parser: syntactically allow `self` in all `fn` contexts
Part of https://github.com/rust-lang/rust/pull/68728.
`self` parameters are now *syntactically* allowed as the first parameter irrespective of item context (and in function pointers). Instead, semantic validation (`ast_validation`) is used.
r? @petrochenkov
Suggest path separator for single-colon typos
This commit adds guidance for when a user means to type a path, but ends
up typing a single colon, such as `<<Impl as T>:Ty>`.
This change seemed pertinent as the current error message is
particularly misleading, emitting `error: unmatched angle bracket`,
despite the angle bracket being matched later on, leaving the user to
track down the typo'd colon.
Shrink `Nonterminal`
These commits shrink `Nonterminal` from 240 bytes to 40 bytes. When building `serde_derive` they reduce the number of `memcpy` calls from 9.6M to 7.4M, and it's a tiny win on a few other benchmarks.
r? @petrochenkov
This commit adds guidance for when a user means to type a path, but ends
up typing a single colon, such as `<<Impl as T>:Ty>`.
This change seemed pertinent as the current error message is
particularly misleading, emitting `error: unmatched angle bracket`,
despite the angle bracket being matched later on, leaving the user to
track down the typo'd colon.
This commit reduces the size of `Nonterminal` from a whopping 240 bytes
to 72 bytes (on x86-64), which gets it below the `memcpy` threshold.
It also removes some impedance mismatches with `Annotatable`, which
already uses `P` for these variants.
Implement `?const` opt-out for trait bounds
For now, such bounds are treated exactly the same as unprefixed ones in all contexts. [RFC 2632](https://github.com/rust-lang/rfcs/pull/2632) does not specify whether such bounds are forbidden outside of `const` contexts, so they are allowed at the moment.
Prior to this PR, the constness of a trait bound/impl was stored in `TraitRef`. Now, the constness of an `impl` is stored in `ast::ItemKind::Impl` and the constness of a bound in `ast::TraitBoundModifer`. Additionally, constness of trait bounds is now stored in an additional field of `ty::Predicate::Trait`, and the combination of the constness of the item along with any `TraitBoundModifier` determines the constness of the bound in accordance with the RFC. Encoding the constness of impls at the `ty` level is left for a later PR.
After a discussion in \#wg-grammar on Discord, it was decided that the grammar should not encode the mutual exclusivity of trait bound modifiers. The grammar for trait bound modifiers remains `[?const] [?]`. To encode this, I add a dummy variant to `ast::TraitBoundModifier` that is used when the syntax `?const ?` appears. This variant causes an error in AST validation and disappears during HIR lowering.
cc #67794
r? @oli-obk
Remove `rustc_error_codes` deps except in `rustc_driver`
Remove dependencies on `rustc_error_codes` in all crates except for `rustc_driver`.
This has some benefits:
1. Adding a new error code when hacking on the compiler only requires rebuilding at most `rustc_error_codes`, `rustc_driver`, and the reflexive & transitive closure of the crate where the new error code is being added and its reverse dependencies. This improves time-to-UI-tests (TTUT).
2. Adding an error description to an error code only requires rebuilding `rustc_error_codes` and `rustc_driver`. This should substantially improve TTUT.
r? @petrochenkov
cc @rust-lang/wg-diagnostics
Clean up some diagnostics by making them more consistent
In general:
- Diagnostic should start with a lowercase letter.
- Diagnostics should not end with a full stop.
- Ellipses contain three dots.
- Backticks should encode Rust code.
I also reworded a couple of messages to make them read more clearly.
It might be sensible to create a style guide for diagnostics, so these informal conventions are written down somewhere, after which we could audit the existing diagnostics.
r? @Centril
Add suggestions when encountering chained comparisons
Ideally, we'd also prevent the type error, which is just extra noise, but that will require moving the error from the parser, and I think the suggestion makes things clear enough for now.
Fixes https://github.com/rust-lang/rust/issues/65659.
bors