By default, `newtype_index!` types get a default `Encodable`/`Decodable`
impl. You can opt out of this with `custom_encodable`. Opting out is the
opposite to how Rust normally works with autogenerated (derived) impls.
This commit inverts the behaviour, replacing `custom_encodable` with
`encodable` which opts into the default `Encodable`/`Decodable` impl.
Only 23 of the 59 `newtype_index!` occurrences need `encodable`.
Even better, there were eight crates with a dependency on
`rustc_serialize` just from unused default `Encodable`/`Decodable`
impls. This commit removes that dependency from those eight crates.
Make regionck care about placeholders in outlives components
Currently, we don't consider a placeholder type `!T` to be a type component when it comes to processing type-outlives obligations. This means that they are essentially treated like unit values with no sub-components, and always outlive any region. This is problematic for `non_lifetime_binders`, and even more problematic for `with_negative_coherence`, since negative coherence uses placeholders as universals.
This PR adds `Component::Placeholder` which acts much like `Component::Param`. This currently causes a regression in some non-lifetime-binders tests because `for<T> T: 'static` doesn't imply itself when processing outlives obligations, so code like this will fail:
```
fn foo() where for<T> T: 'static {
foo() //~ fails
}
```
Since the where clause doesn't imply itself. This requires making the `MatchAgainstHigherRankedOutlives` relation smarter when it comes to binders.
r? types
Ignore but do not assume region obligations from unifying headers in negative coherence
Partly addresses a FIXME that was added in #112875. Just as we can throw away the nested trait/projection obligations from unifying two impl headers, we can also just throw away the region obligations too.
I removed part of the FIXME that was incorrect, namely:
> Given that the only region constraints we get are involving inference regions in the root, it shouldn't matter, but still sus.
This is not true when unifying `fn(A)` and `for<'b> fn(&'b B)` which ends up with placeholder region outlives from non-root universes. I'm pretty sure this is okay, though it would be nice if we were to use them as assumptions. See the `explicit` revision of the test I committed, which still fails.
Fixes#117986
r? lcnr, feel free to reassign tho.
Add some additional warnings for duplicated diagnostic items
This commit adds warnings if a user supplies several diagnostic options where we can only apply one of them. We explicitly warn about ignored options here. In addition a small test for these warnings is added.
r? `@compiler-errors`
For now that's the last PR to improve the warnings generated by misused `#[diagnostic::on_unimplemented]` attributes. I'm not sure what needs to be done next to move this closer to stabilization.
ignore implied bounds with placeholders
given the following code:
```rust
trait Trait {
type Ty<'a> where Self: 'a;
}
impl<T> Trait for T {
type Ty<'a> = () where Self: 'a;
}
struct Foo<T: Trait>(T)
where
for<'x> T::Ty<'x>: Sized;
```
when computing the implied bounds from `Foo<X>` we incorrectly get the bound `X: !x` from the normalization of ` for<'x> <X as Trait>::Ty::<'x>: Sized`. This is a a known bug! we shouldn't use the constraints that arise from normalization as implied bounds. See #109628.
Ignore these bounds for now. This should prevent later ICEs.
Fixes#112250Fixes#107409
new solver normalization improvements
cool beans
At the core of this PR is a `try_normalize_ty` which stops for rigid aliases by using `commit_if_ok`.
Reworks alias-relate to fully normalize both the lhs and rhs and then equate the resulting rigid (or inference) types. This fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/68 by avoiding the exponential blowup. Also supersedes #116369 by only defining opaque types if the hidden type is rigid.
I removed the stability check in `EvalCtxt::evaluate_goal` due to https://github.com/rust-lang/trait-system-refactor-initiative/issues/75. While I personally have opinions on how to fix it, that still requires further t-types/`@nikomatsakis` buy-in, so I removed that for now. Once we've decided on our approach there, we can revert this commit.
r? `@compiler-errors`
This commit adds warnings if a user supplies several diagnostic options
where we can only apply one of them. We explicitly warn about ignored
options here. In addition a small test for these warnings is added.
Fix depth check in ProofTreeVisitor.
The hack to cutoff overflows and cycles in the new trait solver was incorrect. We want to inspect everything with depth [0..10].
This fix exposed a previously unseen bug, which caused the compiler to ICE when invoking `trait_ref` on a non-assoc type projection. I simply added the guard in the `AmbiguityCausesVisitor`, and updated the expected output for the `auto-trait-coherence` test which now includes the extra note:
```text
|
= note: upstream crates may add a new impl of trait `std::marker::Send` for type `OpaqueType` in future versions
```
r? `@lcnr`
Rollup of 4 pull requests
Successful merges:
- #114224 (rustc_llvm: Link to libkstat on Solaris/SPARC)
- #117695 (Reorder checks to make sure potential missing expect on Option/Result…)
- #117870 (`fn args_ref_X` to `fn args_X`)
- #117879 (tests: update check for inferred nneg on zext)
r? `@ghost`
`@rustbot` modify labels: rollup
generator layout: ignore fake borrows
fixes#117059
We emit fake shallow borrows in case the scrutinee place uses a `Deref` and there is a match guard. This is necessary to prevent the match guard from mutating the scrutinee: fab1054e17/compiler/rustc_mir_build/src/build/matches/mod.rs (L1250-L1265)
These fake borrows end up impacting the generator witness computation in `mir_generator_witnesses`, which causes the issue in #117059. This PR now completely ignores fake borrows during this computation. This is sound as thse are always removed after analysis and the actual computation of the generator layout happens afterwards.
Only the second commit impacts behavior, and could be backported by itself.
r? types
Extend builtin/auto trait args with error when they have >1 argument
Reuse `extend_with_error` to add error args to any auto trait (or built-in trait like `Copy` that is defined incorrectly) that has additional non-`Self` args.
Fixes#117628
