In `Expander::expand` the code currently uses `mk_attr_outer` to convert
a `MetaItem` to an `Attribute`, and then follows that with
`meta_item_list` which converts back. This commit avoids the unnecessary
conversions.
There was one wrinkle: the existing conversions caused the bogus `<>` on
`Default<>` to be removed. With the conversion gone, we get a second
error message about the `<>`. This is a rare case, so I think it
probably doesn't matter much.
Add context to compiler error message
Changed `creates a temporary which is freed while still in use` to `creates a temporary value which is freed while still in use`.
Support default-body trait functions with return-position `impl Trait` in traits
Introduce a new `Trait` candidate kind for the `ImplTraitInTrait` projection candidate, which just projects an RPITIT down to its opaque type form.
This is a hack until we lower RPITITs to regular associated types, after which we will need to rework how these default bodies are type-checked, so comments are left in a few places for us to clean up later.
Fixes#101665
Allow more `!Copy` impls
You can already implement `!Copy` for a lot of types (with `#![feature(negative_impls)]`). However, before this PR you could not implement `!Copy` for ADTs whose fields don't implement `Copy` which didn't make any sense. Further, you couldn't implement `!Copy` for types impl'ing `Drop` (equally nonsensical).
``@rustbot`` label T-types F-negative_impls
Fixes#101836.
r? types
Split out async_fn_in_trait into a separate feature
PR #101224 added support for async fn in trait desuraging behind the `return_position_impl_trait_in_trait` feature.
Split this out so that it's behind its own feature gate, since async fn in trait doesn't need to follow the same stabilization schedule.
PR #101224 added support for async fn in trait desuraging behind the
return_position_impl_trait_in_trait feature.
Split this out so that it's behind its own feature gate, since async fn
in trait doesn't need to follow the same stabilization schedule.
never consider unsafe blocks unused if they would be required with deny(unsafe_op_in_unsafe_fn)
Judging from https://github.com/rust-lang/rust/issues/71668#issuecomment-1200317370 the consensus nowadays seems to be that we should never consider an unsafe block unused if it was required with `deny(unsafe_op_in_unsafe_fn)`, no matter whether that lint is actually enabled or not. So let's adjust rustc accordingly.
The first commit does the change, the 2nd does some cleanup.
We check that there's a single level of block nesting to ensure always
correct suggestions. If we don't, then we only provide a free-form
message to avoid misleading users in cases like
`src/test/ui/nll/borrowed-temporary-error.rs`.
We could expand the analysis to suggest hoising all of the relevant
parts of the users' code to make the code compile, but that could be
too much.
Track implicit `Sized` obligations in type params
When we evaluate `ty::GenericPredicates` we introduce the implicit
`Sized` predicate of type params, but we do so with only the `Predicate`
its `Span` as context, we don't have an `Obligation` or
`ObligationCauseCode` we could influence. To try and carry this
information through, we add a new field to `ty::GenericPredicates` that
tracks both which predicates come from a type param and whether that
param has any bounds already (to use in suggestions).
We also suggest adding a `?Sized` bound if appropriate on E0599.
Address part of #98539.
Improve some inference diagnostics
- Properly point out point location where "type must be known at this point", or else omit the note if it's not associated with a useful span.
- Fix up some type ambiguity diagnostics, errors shouldn't say "cannot infer type for reference `&'a ()`" when the given type has no inference variables.
Shorten def_span for more items.
The `def_span` query only returns the signature span for functions.
Struct/enum/union definitions can also have a very long body.
This PR shortens the associated span.
Rollup of 6 pull requests
Successful merges:
- #97488 (Suggest blanket impl to the local traits)
- #98585 (Make `ThinBox<T>` covariant in `T`)
- #98644 (fix ICE with -Wrust-2021-incompatible-closure-captures)
- #98739 (fix grammar in useless doc comment lint)
- #98741 (Many small deriving cleanups)
- #98756 (Use const instead of function and make it private)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Rewrite dead-code pass to avoid fetching HIR.
This allows to get a more uniform handling of spans, and to simplify the grouping of diagnostics for variants and fields.
