handle member constraints directly in the mir type checker
cleaner, faster, easier to change going forward :> fixes#109654
r? `@oli-obk` `@compiler-errors`
Re-export more `rustc_span::symbol` things from `rustc_span`.
`rustc_span::symbol` defines some things that are re-exported from `rustc_span`, such as `Symbol` and `sym`. But it doesn't re-export some closely related things such as `Ident` and `kw`. So you can do `use rustc_span::{Symbol, sym}` but you have to do `use rustc_span::symbol::{Ident, kw}`, which is inconsistent for no good reason.
This commit re-exports `Ident`, `kw`, and `MacroRulesNormalizedIdent`, and changes many `rustc_span::symbol::` qualifiers to `rustc_span::`. This is a 300+ net line of code reduction, mostly because many files with two `use rustc_span` items can be reduced to one.
r? `@jieyouxu`
`rustc_span::symbol` defines some things that are re-exported from
`rustc_span`, such as `Symbol` and `sym`. But it doesn't re-export some
closely related things such as `Ident` and `kw`. So you can do `use
rustc_span::{Symbol, sym}` but you have to do `use
rustc_span::symbol::{Ident, kw}`, which is inconsistent for no good
reason.
This commit re-exports `Ident`, `kw`, and `MacroRulesNormalizedIdent`,
and changes many `rustc_span::symbol::` qualifiers in `compiler/` to
`rustc_span::`. This is a 200+ net line of code reduction, mostly
because many files with two `use rustc_span` items can be reduced to
one.
Add some convenience helper methods on `hir::Safety`
Makes a lot of call sites simpler and should make any refactorings needed for https://github.com/rust-lang/rust/pull/134090#issuecomment-2541332415 simpler, as fewer sites have to be touched in case we end up storing some information in the variants of `hir::Safety`
Move impl constness into impl trait header
This PR is kind of the opposite of the rejected https://github.com/rust-lang/rust/pull/134114
Instead of moving more things into the `constness` query, we want to keep them where their corresponding hir nodes are lowered. So I gave this a spin for impls, which have an obvious place to be (the impl trait header). And surprisingly it's also a perf improvement (likely just slightly better query & cache usage).
The issue was that removing anything from the `constness` query makes it just return `NotConst`, which is wrong. So I had to change it to `bug!` out if used wrongly, and only then remove the impl blocks from the `constness` query. I think this change is good in general, because it makes using `constness` more robust (as can be seen by how few sites that had to be changed, so it was almost solely used specifically for the purpose of asking for functions' constness). The main thing where this change was not great was in clippy, which was using the `constness` query as a general DefId -> constness map. I added a `DefKind` filter in front of that. If it becomes a more common pattern we can always move that helper into rustc.
Add unpolished, experimental support for AFIDT (async fn in dyn trait)
This allows us to begin messing around `async fn` in `dyn Trait`. Calling an async fn from a trait object always returns a `dyn* Future<Output = ...>`.
To make it work, Implementations are currently required to return something that can be coerced to a `dyn* Future` (see the example in `tests/ui/async-await/dyn/works.rs`). If it's not the right size, then it'll raise an error at the coercion site (see the example in `tests/ui/async-await/dyn/wrong-size.rs`). Currently the only practical way of doing this is wrapping the body in `Box::pin(async move { .. })`.
This PR does not implement a helper type like a "`Boxing`"[^boxing] adapter, and I'll probably follow-up with another PR to improve the error message for the `PointerLike` trait (something that explains in just normal prose what is happening here, rather than a trait error).
[^boxing]: https://rust-lang.github.io/async-fundamentals-initiative/explainer/user_guide_future.html#the-boxing-adapter
This PR also does not implement new trait solver support for AFIDT; I'll need to think how best to integrate it into candidate assembly, and that's a bit of a matter of taste, but I don't think it will be difficult to do.
This could also be generalized:
* To work on functions that are `-> impl Future` (soon).
* To work on functions that are `-> impl Iterator` and other "dyn rpitit safe" traits. We still need to nail down exactly what is needed for this to be okay (not soon).
Tracking:
* https://github.com/rust-lang/rust/issues/133119
As a rule, the application of `unsafe` to a declaration requires that use-sites
of that declaration also require `unsafe`. For example, a field declared
`unsafe` may only be read in the lexical context of an `unsafe` block.
For nearly all safe traits, the safety obligations of fields are explicitly
discharged when they are mentioned in method definitions. For example,
idiomatically implementing `Clone` (a safe trait) for a type with unsafe fields
will require `unsafe` to clone those fields.
Prior to this commit, `Copy` violated this rule. The trait is marked safe, and
although it has no explicit methods, its implementation permits reads of `Self`.
This commit resolves this by making `Copy` conditionally safe to implement. It
remains safe to implement for ADTs without unsafe fields, but unsafe to
implement for ADTs with unsafe fields.
Tracking: #132922
If a type has unsafe fields, its safety invariants are not simply
the conjunction of its field types' safety invariants. Consequently,
it's invalid to reason about the safety properties of these types
in a purely structural manner — i.e., the manner in which `auto`
traits are implemented.
Makes progress towards #132922.
Rollup of 10 pull requests
Successful merges:
- #118833 (Add lint against function pointer comparisons)
- #122161 (Fix suggestion when shorthand `self` has erroneous type)
- #133233 (Add context to "const in pattern" errors)
- #133761 (Update books)
- #133843 (Do not emit empty suggestion)
- #133863 (Rename `core_pattern_type` and `core_pattern_types` lib feature gates to `pattern_type_macro`)
- #133872 (No need to create placeholders for GAT args in confirm_object_candidate)
- #133874 (`fn_sig_for_fn_abi` should return a `ty::FnSig`, no need for a binder)
- #133890 (Add a new test ui/incoherent-inherent-impls/no-other-unrelated-errors to check E0116 does not cause unrelated errors)
- #133892 (Revert #133817)
r? `@ghost`
`@rustbot` modify labels: rollup
Deeply normalize when computing implied outlives bounds
r? lcnr
Unfortunately resolving regions is still slightly scuffed (though in an unrelated way). Specifically, we should be normalizing our param-env outlives when constructing the `OutlivesEnv`; otherwise, these assumptions (dd2837ec5d/compiler/rustc_infer/src/infer/outlives/env.rs (L78)) are not constructed correctly.
Let me know if you want us to track that somewhere.
check local cache even if global is usable
we store overflow errors locally, even if we can otherwise use the global cache for this goal. should fix#133616, didn't test it locally yet as diesel tends to hit an unrelated debug assertion in rustdoc.
r? types
Some minor dyn-related tweaks
Each commit should be self-explanatory, but I'm happy to explain what's going on if not. These are tweaks I pulled out of #133388, but they can be reviewed sooner than that.
r? types
finish `Reveal` removal
After #133212 changed the `TypingMode` to be the only source of truth, this entirely rips out `Reveal`.
cc #132279
r? `@compiler-errors`
