This ensures that the error is printed even for unused variables,
as well as unifying the handling between the LLVM and GCC backends.
This also fixes unusual behavior around exported Rust-defined variables
with linkage attributes. With the previous behavior, it appears to be
impossible to define such a variable such that it can actually be imported
and used by another crate. This is because on the importing side, the
variable is required to be a pointer, but on the exporting side, the
type checker rejects static variables of pointer type because they do
not implement `Sync`. Even if it were possible to import such a type, it
appears that code generation on the importing side would add an unexpected
additional level of pointer indirection, which would break type safety.
This highlighted that the semantics of linkage on Rust-defined variables
is different to linkage on foreign items. As such, we now model the
difference with two different codegen attributes: linkage for Rust-defined
variables, and import_linkage for foreign items.
This change gives semantics to the test
src/test/ui/linkage-attr/auxiliary/def_illtyped_external.rs which was
previously expected to fail to compile. Therefore, convert it into a
test that is expected to successfully compile.
The update to the GCC backend is speculative and untested.
Rollup of 6 pull requests
Successful merges:
- #101975 (Suggest to use . instead of :: when accessing a method of an object)
- #105141 (Fix ICE on invalid variable declarations in macro calls)
- #105224 (Properly substitute inherent associated types.)
- #105236 (Add regression test for #47814)
- #105247 (Use parent function WfCheckingContext to check RPITIT.)
- #105253 (Update a couple of rustbuild deps)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
This avoids creation of a terminating scope in
chains that contain both && and ||, because
also there we know that a terminating scope is
not neccessary: all the chain members are already
in such terminating scopes.
Also add a mixed && / || test.
Previously a short circuiting && chain would drop the
first element after all the other elements, and otherwise
follow evaluation order, so code like:
f(1).g() && f(2).g() && f(3).g() && f(4).g()
would drop the temporaries in the order 2,3,4,1. This made
&& and || non-associative regarding drop order, so
adding ()'s to the expression would change drop order:
f(1).g() && (f(2).g() && f(3).g()) && f(4).g()
for example would drop in the order 3,2,4,1.
As, except for the bool result, there is no data returned
by the sub-expressions of the short circuiting binops,
we can safely discard of any temporaries created by the
sub-expr. Previously, code was already putting the rhs's
into terminating scopes, but missed it for the lhs's.
This commit addresses this "twist". In the expression,
we now also put the lhs into a terminating scope.
The drop order for the above expressions is 1,2,3,4
now.
Remove a lifetime resolution hack from `compare_predicate_entailment`
This is not needed anymore, probably due to #102334 equating the function signatures fully in `collect_trait_impl_trait_tys`. Also, the assertion in in #102903 makes sure that this is actually fixed, so I'm pretty confident this isn't needed.
Support using `Self` or projections inside an RPIT/async fn
I reuse the same idea as https://github.com/rust-lang/rust/pull/103449 to use variances to encode whether a lifetime parameter is captured by impl-trait.
The current implementation of async and RPIT replace all lifetimes from the parent generics by `'static`. This PR changes the scheme
```rust
impl<'a> Foo<'a> {
fn foo<'b, T>() -> impl Into<Self> + 'b { ... }
}
opaque Foo::<'_a>::foo::<'_b, T>::opaque<'b>: Into<Foo<'_a>> + 'b;
impl<'a> Foo<'a> {
// OLD
fn foo<'b, T>() -> Foo::<'static>::foo::<'static, T>::opaque::<'b> { ... }
^^^^^^^ the `Self` becomes `Foo<'static>`
// NEW
fn foo<'b, T>() -> Foo::<'a>::foo::<'b, T>::opaque::<'b> { ... }
^^ the `Self` stays `Foo<'a>`
}
```
There is the same issue with projections. In the example, substitute `Self` by `<T as Trait<'b>>::Assoc` in the sugared version, and `Foo<'_a>` by `<T as Trait<'_b>>::Assoc` in the desugared one.
This allows to support `Self` in impl-trait, since we do not replace lifetimes by `'static` any more. The same trick allows to use projections like `T::Assoc` where `Self` is allowed. The feature is gated behind a `impl_trait_projections` feature gate.
The implementation relies on 2 tweaking rules for opaques in 2 places:
- we only relate substs that correspond to captured lifetimes during TypeRelation;
- we only list captured lifetimes in choice region computation.
For simplicity, I encoded the "capturedness" of lifetimes as a variance, `Bivariant` vs `Invariant` for unused vs captured lifetimes. The `variances_of` query used to ICE for opaques.
Impl-trait that do not reference `Self` or projections will have their variances as:
- `o` (invariant) for each parent type or const;
- `*` (bivariant) for each parent lifetime --> will not participate in borrowck;
- `o` (invariant) for each own lifetime.
Impl-trait that does reference `Self` and/or projections will have some parent lifetimes marked as `o` (as the example above), and participate in type relation and borrowck. In the example above, `variances_of(opaque) = ['_a: o, '_b: *, T: o, 'b: o]`.
r? types
cc `@compiler-errors` , as you asked about the issue with `Self` and projections.
Improve spans for RPITIT object-safety errors
No reason why we can't point at the `impl Trait` that causes the object-safety violation.
Also [drive-by: Add is_async fn to hir::IsAsync](c4165f3a96), which touches clippy too.
nll: correctly deal with bivariance
fixes#104409
when in a bivariant context, relating stuff should always trivially succeed. Also changes the mir validator to correctly deal with higher ranked regions.
r? types cc ``@RalfJung``
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).
Don't remap early-bound regions for return-position `impl Trait` in trait originating from `impl`
long title 😓
We don't want to remap early-bound regions that originate from the `impl`s themselves, since they have no corresponding region in the trait. Not sure if there's a better condition than checking if the EBR's def-id's parent is the impl -- maybe we should be checking if the region comes from the method or RPITIT... 🤷
r? types
Fixes#103850
Record `LocalDefId` in HIR nodes instead of a side table
This is part of an attempt to remove the `HirId -> LocalDefId` table from HIR.
This attempt is a prerequisite to creation of `LocalDefId` after HIR lowering (https://github.com/rust-lang/rust/pull/96840), by controlling how `def_id` information is accessed.
This first part adds the information to HIR nodes themselves instead of a table.
The second part is https://github.com/rust-lang/rust/pull/103902
The third part will be to make `hir::Visitor::visit_fn` take a `LocalDefId` as last parameter.
The fourth part will be to completely remove the side table.
interpret: support for per-byte provenance
Also factors the provenance map into its own module.
The third commit does the same for the init mask. I can move it in a separate PR if you prefer.
Fixes https://github.com/rust-lang/miri/issues/2181
r? `@oli-obk`
