Process alias-relate obligations in CoerceUnsized loop #121702
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…e, r=lcnr Process alias-relate obligations in CoerceUnsized loop After rust-lang#119106, we now emit `AliasRelate` goals when relating `?0` and `Alias<T, ..>` in the new solver. In the ad-hoc `CoerceUnsized` selection loop, we now may have `AliasRelate` goals which must be processed to constrain type variables which are mentioned in other goals. --- For example, in the included test, we try to coerce `&<ManuallyDrop<T> as Deref>::Target` to `&dyn Foo`. This requires proving: * 1 `&<ManuallyDrop<T> as Deref>::Target: CoerceUnsized<&dyn Foo>` * 2 `<ManuallyDrop<T> as Deref>::Target alias-relate ?0` * 3 `?0: Unsize<dyn Foo>` * 4 `?0: Foo` * 5 `?0: Sized` If we don't process goal (2.) before processing goal (3.), then we hit ambiguity since `?0` is never constrained, and therefore we bail out, refusing to coerce the types. After processing (2.), we know `?0 := T`, and the rest of the goals can be processed normally.
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…llaumeGomez Rollup of 13 pull requests Successful merges: - rust-lang#120051 (Add `display` method to `OsStr`) - rust-lang#121226 (Fix issues in suggesting importing extern crate paths) - rust-lang#121423 (Remove the `UntranslatableDiagnosticTrivial` lint.) - rust-lang#121527 (unix_sigpipe: Simple fixes and improvements in tests) - rust-lang#121572 (Add test case for primitive links in alias js) - rust-lang#121661 (Changing some attributes to only_local.) - rust-lang#121680 (Fix link generation for foreign macro in jump to definition feature) - rust-lang#121686 (Adjust printing for RPITITs) - rust-lang#121689 ([rustdoc] Prevent inclusion of whitespace character after macro_rules ident) - rust-lang#121691 (handle unavailable creation time as `io::ErrorKind::Unsupported`) - rust-lang#121695 (Split rustc_type_ir to avoid rustc_ast from depending on it) - rust-lang#121698 (CFI: Fix typo in test file names) - rust-lang#121702 (Process alias-relate obligations in CoerceUnsized loop) r? `@ghost` `@rustbot` modify labels: rollup
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…llaumeGomez Rollup of 12 pull requests Successful merges: - rust-lang#120051 (Add `display` method to `OsStr`) - rust-lang#121226 (Fix issues in suggesting importing extern crate paths) - rust-lang#121423 (Remove the `UntranslatableDiagnosticTrivial` lint.) - rust-lang#121527 (unix_sigpipe: Simple fixes and improvements in tests) - rust-lang#121572 (Add test case for primitive links in alias js) - rust-lang#121661 (Changing some attributes to only_local.) - rust-lang#121680 (Fix link generation for foreign macro in jump to definition feature) - rust-lang#121686 (Adjust printing for RPITITs) - rust-lang#121691 (handle unavailable creation time as `io::ErrorKind::Unsupported`) - rust-lang#121695 (Split rustc_type_ir to avoid rustc_ast from depending on it) - rust-lang#121698 (CFI: Fix typo in test file names) - rust-lang#121702 (Process alias-relate obligations in CoerceUnsized loop) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#121702 - compiler-errors:coerce-alias-relate, r=lcnr Process alias-relate obligations in CoerceUnsized loop After rust-lang#119106, we now emit `AliasRelate` goals when relating `?0` and `Alias<T, ..>` in the new solver. In the ad-hoc `CoerceUnsized` selection loop, we now may have `AliasRelate` goals which must be processed to constrain type variables which are mentioned in other goals. --- For example, in the included test, we try to coerce `&<ManuallyDrop<T> as Deref>::Target` to `&dyn Foo`. This requires proving: * 1 `&<ManuallyDrop<T> as Deref>::Target: CoerceUnsized<&dyn Foo>` * 2 `<ManuallyDrop<T> as Deref>::Target alias-relate ?0` * 3 `?0: Unsize<dyn Foo>` * 4 `?0: Foo` * 5 `?0: Sized` If we don't process goal (2.) before processing goal (3.), then we hit ambiguity since `?0` is never constrained, and therefore we bail out, refusing to coerce the types. After processing (2.), we know `?0 := T`, and the rest of the goals can be processed normally.
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After #119106, we now emit
AliasRelategoals when relating?0andAlias<T, ..>in the new solver. In the ad-hocCoerceUnsizedselection loop, we now may haveAliasRelategoals which must be processed to constrain type variables which are mentioned in other goals.For example, in the included test, we try to coerce
&<ManuallyDrop<T> as Deref>::Targetto&dyn Foo. This requires proving:&<ManuallyDrop<T> as Deref>::Target: CoerceUnsized<&dyn Foo><ManuallyDrop<T> as Deref>::Target alias-relate ?0?0: Unsize<dyn Foo>?0: Foo?0: SizedIf we don't process goal (2.) before processing goal (3.), then we hit ambiguity since
?0is never constrained, and therefore we bail out, refusing to coerce the types. After processing (2.), we know?0 := T, and the rest of the goals can be processed normally.