Account for RPITIT in E0310 explicit lifetime constraint suggestion
When given
```rust
trait Original {
fn f() -> impl Fn();
}
trait Erased {
fn f(&self) -> Box<dyn Fn()>;
}
impl<T: Original> Erased for T {
fn f(&self) -> Box<dyn Fn()> {
Box::new(<T as Original>::f())
}
}
```
emit do not emit an invalid suggestion restricting the `Trait::{opaque}` type in a `where` clause:
```
error[E0310]: the associated type `<T as Original>::{opaque#0}` may not live long enough
--> $DIR/missing-static-bound-from-impl.rs:11:9
|
LL | Box::new(<T as Original>::f())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| the associated type `<T as Original>::{opaque#0}` must be valid for the static lifetime...
| ...so that the type `impl Fn()` will meet its required lifetime bounds
```
Partially address #119773. Ideally we'd suggest modifying `Erased::f` instead.
r? `@compiler-errors`
When given
```rust
trait Original {
fn f() -> impl Fn();
}
trait Erased {
fn f(&self) -> Box<dyn Fn()>;
}
impl<T: Original> Erased for T {
fn f(&self) -> Box<dyn Fn()> {
Box::new(<T as Original>::f())
}
}
```
avoid suggestion to restrict the `Trait::{opaque}` type in a `where` clause:
```
error[E0310]: the associated type `<T as Original>::{opaque#0}` may not live long enough
--> $DIR/missing-static-bound-from-impl.rs:11:9
|
LL | Box::new(<T as Original>::f())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| the associated type `<T as Original>::{opaque#0}` must be valid for the static lifetime...
| ...so that the type `impl Fn()` will meet its required lifetime bounds
```
CC #119773.
Properly handle `async` block and `async fn` in `if` exprs without `else`
When encountering a tail expression in the then arm of an `if` expression without an `else` arm, account for `async fn` and `async` blocks to suggest `return`ing the value and pointing at the return type of the `async fn`.
We now also account for AFIT when looking for the return type to point at.
Fix#115405.
When encountering a tail expression in the then arm of an `if` expression
without an `else` arm, account for `async fn` and `async` blocks to
suggest `return`ing the value and pointing at the return type of the
`async fn`.
We now also account for AFIT when looking for the return type to point at.
Fix#115405.
```
error[E0277]: the size for values of type `[i32]` cannot be known at compilation time
--> f100.rs:2:33
|
2 | let _ = std::mem::size_of::<[i32]>();
| ^^^^^ doesn't have a size known at compile-time
|
= help: the trait `Sized` is not implemented for `[i32]`
note: required by an implicit `Sized` bound in `std::mem::size_of`
--> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22
|
312 | pub const fn size_of<T>() -> usize {
| ^ required by the implicit `Sized` requirement on this bound in `size_of`
```
Fix#120178.
Change the implicit `Sized` `Obligation` `Span` for call expressions to
include the whole expression. This aids the existing deduplication
machinery to reduce the number of errors caused by a single unsized
expression.
When we encounter a `dyn Trait` that isn't object safe, look for its
implementors. If there's one, mention using it directly If there are
less than 9, mention the possibility of creating a new enum and using
that instead.
Account for object unsafe `impl Trait on dyn Trait {}`. Make a
distinction between public and sealed traits.
Fix#80194.
Relate alias ty with variance
In the new solver, turns out that the subst-relate branch of the alias-relate predicate was relating args invariantly even for opaques, which have variance 💀.
This change is a bit more invasive, but I'd rather not special-case it [here](aeaa5c30e5/compiler/rustc_trait_selection/src/solve/alias_relate.rs (L171-L190)) and then have it break elsewhere. I'm doing a perf run to see if the extra call to `def_kind` is that expensive, if it is, I'll reconsider.
r? ``@lcnr``
More accurately point to where default return type should go
When getting the "default return type" span, instead of pointing to the low span of the next token, point to the high span of the previous token. This:
1. Makes forming return type suggestions more uniform, since we expect them all in the same place.
2. Arguably makes labels easier to understand, since we're pointing to where the implicit `-> ()` would've gone, rather than the starting brace or the semicolon.
r? ```@estebank```
Don't check unnecessarily that impl trait is RPIT
We have this random `return_type_impl_trait` function to detect if a function returns an RPIT which is used in outlives suggestions, but removing it doesn't actually change any diagnostics. Let's just remove it.
Also, suppress a spurious outlives error from a ReError.
Fixes#114274
Map RPITIT's opaque type bounds back from projections to opaques
An RPITIT in a program's AST is eventually translated into both a projection GAT and an opaque. The opaque is used for default trait methods, like:
```
trait Foo {
fn bar() -> impl Sized { 0i32 }
}
```
The item bounds for both the projection and opaque are identical, and both have a *projection* self ty. This is mostly okay, since we can normalize this projection within the default trait method body to the opaque, but it does two things:
1. it leads to bugs in places where we don't normalize item bounds, like `deduce_future_output_from_obligations`
2. it leads to extra match arms that are both suspicious looking and also easy to miss
This PR maps the opaque type bounds of the RPITIT's *opaque* back to the opaque's self type to avoid this quirk. Then we can fix the UI test for #108304 (1.) and also remove a bunch of match arms (2.).
Fixes#108304
r? `@spastorino`
Make RPITITs assume/require their parent method's predicates
Removes a FIXME from the `param_env` query where we were manually adding the parent function's predicates to the RPITIT's assumptions.
r? `@spastorino`
Error when RPITITs' hidden types capture more lifetimes than their trait definitions
This implements a stricter set of captures rules for RPITITs. They now may only capture:
1. Lifetimes from the impl header (both the self type and any trait substs -- we may want to restrict just to the self type's lifetimes, but the PR makes that easy to do, too)
2. Lifetimes mentioned by the `impl Trait` in the trait method's definition.
Namely, they may not mention lifetimes from the method (early or late) that are not mentioned in the `impl Trait`.
cc #105258 which I think was trying to do this too, though I'm not super familiar with what exactly differs from that or why that one was broken.
cc #112194 (doesn't fix this issue per se, because it's still an open question, but I think this is objectively better than the status quo, and gets us closer to resolving that issue.)
Technically is a fix for the ICE in #108580, but it turns that issue into an error now. We can decide separately whether or not nested RPITITs should capture lifetimes from their parents.
r? ``@oli-obk``
Encode def span for foreign return-position `impl Trait` in trait
Fixes#111031, yet another def-span encoding issue :/
Includes a smaller repro than the issue, but I can confirm it ICEs:
```
query stack during panic:
#0 [def_span] looking up span for `rpitit::Foo::bar::{opaque#0}`
#1 [object_safety_violations] determining object safety of trait `rpitit::Foo`
#2 [check_is_object_safe] checking if trait `rpitit::Foo` is object safe
#3 [typeck] type-checking `main`
#4 [used_trait_imports] finding used_trait_imports `main`
#5 [analysis] running analysis passes on this crate
```
Luckily since this only affects nightly, this desn't need to be backported.
Do not consider synthesized RPITITs on missing items checks
Without this patch for `tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs` we get ...
```
warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
--> tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs:4:12
|
4 | #![feature(return_position_impl_trait_in_trait)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= note: `#[warn(incomplete_features)]` on by default
error[E0046]: not all trait items implemented, missing: `foo`, ``
--> tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs:12:1
|
8 | fn foo(&self) -> impl Sized;
| ----------------------------
| | |
| | `` from trait
| `foo` from trait
...
12 | impl MyTrait for i32 {
| ^^^^^^^^^^^^^^^^^^^^ missing `foo`, `` in implementation
error: aborting due to previous error; 1 warning emitted
For more information about this error, try `rustc --explain E0046`.
```
instead of ...
```
warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/dont-project-to-rpitit-with-no-value.rs:4:12
|
LL | #![feature(return_position_impl_trait_in_trait)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= note: `#[warn(incomplete_features)]` on by default
error[E0046]: not all trait items implemented, missing: `foo`
--> $DIR/dont-project-to-rpitit-with-no-value.rs:12:1
|
LL | fn foo(&self) -> impl Sized;
| ---------------------------- `foo` from trait
...
LL | impl MyTrait for i32 {
| ^^^^^^^^^^^^^^^^^^^^ missing `foo` in implementation
error: aborting due to previous error; 1 warning emitted
For more information about this error, try `rustc --explain E0046`.
```
r? `@compiler-errors`
Walk un-shifted nested `impl Trait` in trait when setting up default trait method assumptions
Fixes a double subtraction in some binder math in return-position `impl Trait` in trait handling code.
Fixes#109239
Fix generics_of for impl's RPITIT synthesized associated type
The only useful commit is the last one.
This makes `generics_of` for the impl side RPITIT copy from the trait's associated type and avoid the fn on the impl side which was previously wrongly used.
This solution is better but we still need to fix resolution of the generated generics.
r? ``@compiler-errors``
Fix generics mismatch errors for RPITITs on -Zlower-impl-trait-in-trait-to-assoc-ty
This PR stops reporting errors due to different count of generics on the new synthesized associated types for RPITITs. Those were already reported when we compare the function on the triat with the function on the impl.
r? ``@compiler-errors``
