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Auto merge of rust-lang#125413 - lcnr:ambig-drop-region-constraints, …
…r=compiler-errors drop region constraints for ambiguous goals See the comment in `compute_external_query_constraints`. While the underlying issue is preexisting, this fixes a bug introduced by rust-lang#125343. It slightly weakens the leak chec, even if we didn't have any test which was affected. I want to write such a test before merging this PR. r? `@compiler-errors`
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28 changes: 28 additions & 0 deletions
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tests/ui/higher-ranked/leak-check/leak-check-in-selection-5-ambig.rs
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//@ revisions: old next | ||
//@[next] compile-flags: -Znext-solver | ||
//@ check-pass | ||
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// The new trait solver does not return region constraints if the goal | ||
// is still ambiguous. This causes the following test to fail with ambiguity, | ||
// even though `(): LeakCheckFailure<'!a, V>` would return `'!a: 'static` | ||
// which would have caused a leak check failure. | ||
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trait Ambig {} | ||
impl Ambig for u32 {} | ||
impl Ambig for u16 {} | ||
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trait Id<T> {} | ||
impl Id<u32> for u32 {} | ||
impl Id<u16> for u16 {} | ||
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trait LeakCheckFailure<'a, V: ?Sized> {} | ||
impl<V: ?Sized + Ambig> LeakCheckFailure<'static, V> for () {} | ||
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trait Trait<U, V> {} | ||
impl<V> Trait<u32, V> for () where for<'a> (): LeakCheckFailure<'a, V> {} | ||
impl<V> Trait<u16, V> for () {} | ||
fn impls_trait<T: Trait<U, V>, U: Id<V>, V>() {} | ||
fn main() { | ||
impls_trait::<(), _, _>() | ||
} |
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tests/ui/higher-ranked/leak-check/leak-check-in-selection-6-ambig-unify.next.stderr
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error[E0283]: type annotations needed | ||
--> $DIR/leak-check-in-selection-6-ambig-unify.rs:30:5 | ||
| | ||
LL | impls_trait::<(), _, _>() | ||
| ^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `U` declared on the function `impls_trait` | ||
| | ||
note: multiple `impl`s satisfying `(): Trait<_, _>` found | ||
--> $DIR/leak-check-in-selection-6-ambig-unify.rs:26:1 | ||
| | ||
LL | impl<V> Trait<u32, V> for () where for<'b> (): LeakCheckFailure<'static, 'b, V> {} | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
LL | impl<V> Trait<u16, V> for () {} | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
note: required by a bound in `impls_trait` | ||
--> $DIR/leak-check-in-selection-6-ambig-unify.rs:28:19 | ||
| | ||
LL | fn impls_trait<T: Trait<U, V>, U: Id<V>, V>() {} | ||
| ^^^^^^^^^^^ required by this bound in `impls_trait` | ||
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error: aborting due to 1 previous error | ||
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For more information about this error, try `rustc --explain E0283`. |
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tests/ui/higher-ranked/leak-check/leak-check-in-selection-6-ambig-unify.old.stderr
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error[E0283]: type annotations needed | ||
--> $DIR/leak-check-in-selection-6-ambig-unify.rs:30:5 | ||
| | ||
LL | impls_trait::<(), _, _>() | ||
| ^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `U` declared on the function `impls_trait` | ||
| | ||
note: multiple `impl`s satisfying `(): Trait<_, _>` found | ||
--> $DIR/leak-check-in-selection-6-ambig-unify.rs:26:1 | ||
| | ||
LL | impl<V> Trait<u32, V> for () where for<'b> (): LeakCheckFailure<'static, 'b, V> {} | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
LL | impl<V> Trait<u16, V> for () {} | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
note: required by a bound in `impls_trait` | ||
--> $DIR/leak-check-in-selection-6-ambig-unify.rs:28:19 | ||
| | ||
LL | fn impls_trait<T: Trait<U, V>, U: Id<V>, V>() {} | ||
| ^^^^^^^^^^^ required by this bound in `impls_trait` | ||
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error: aborting due to 1 previous error | ||
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For more information about this error, try `rustc --explain E0283`. |
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tests/ui/higher-ranked/leak-check/leak-check-in-selection-6-ambig-unify.rs
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//@ revisions: old next | ||
//@[next] compile-flags: -Znext-solver | ||
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// The new trait solver does not return region constraints if the goal | ||
// is still ambiguous. This should cause the following test to fail with | ||
// ambiguity as even if `(): LeakCheckFailure<'static, '!b, V>` unifies | ||
// `'!b` with `'static`, we erase all region constraints. | ||
// | ||
// However, we do still unify the var_value for `'b` with `'static`, | ||
// causing us to return this requirement via the `var_values` even if | ||
// we don't return any region constraints. This is a bit inconsistent | ||
// but isn't something we should really worry about imo. | ||
trait Ambig {} | ||
impl Ambig for u32 {} | ||
impl Ambig for u16 {} | ||
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trait Id<T> {} | ||
impl Id<u32> for u32 {} | ||
impl Id<u16> for u16 {} | ||
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trait LeakCheckFailure<'a, 'b, V: ?Sized> {} | ||
impl<'a, 'b: 'a, V: ?Sized + Ambig> LeakCheckFailure<'a, 'b, V> for () {} | ||
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trait Trait<U, V> {} | ||
impl<V> Trait<u32, V> for () where for<'b> (): LeakCheckFailure<'static, 'b, V> {} | ||
impl<V> Trait<u16, V> for () {} | ||
fn impls_trait<T: Trait<U, V>, U: Id<V>, V>() {} | ||
fn main() { | ||
impls_trait::<(), _, _>() | ||
//~^ ERROR type annotations needed | ||
} |
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tests/ui/traits/next-solver/normalize/ambig-goal-infer-in-type-oulives.rs
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//@ check-pass | ||
//@ compile-flags: -Znext-solver | ||
//@ ignore-compare-mode-next-solver (explicitly enabled) | ||
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// Regression test for an ICE when trying to bootstrap rustc | ||
// with #125343. An ambiguous goal returned a `TypeOutlives` | ||
// constraint referencing an inference variable. This inference | ||
// variable was created inside of the goal, causing it to be | ||
// unconstrained in the caller. This then caused an ICE in MIR | ||
// borrowck. | ||
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struct Foo<T>(T); | ||
trait Extend<T> { | ||
fn extend<I: IntoIterator<Item = T>>(iter: I); | ||
} | ||
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impl<T> Extend<T> for Foo<T> { | ||
fn extend<I: IntoIterator<Item = T>>(_: I) { | ||
todo!() | ||
} | ||
} | ||
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impl<'a, T: 'a + Copy> Extend<&'a T> for Foo<T> { | ||
fn extend<I: IntoIterator<Item = &'a T>>(iter: I) { | ||
<Self as Extend<T>>::extend(iter.into_iter().copied()) | ||
} | ||
} | ||
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fn main() {} |