ICE: EvalCtxt is tainted -- nested goals may have been dropped in a previous call to try_evaluate_added_goals`
#134905
Labels
A-specialization
Area: Trait impl specialization
C-bug
Category: This is a bug.
I-ICE
Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️
S-bug-has-test
Status: This bug is tracked inside the repo by a `known-bug` test.
S-has-bisection
Status: a bisection has been found for this issue
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
T-types
Relevant to the types team, which will review and decide on the PR/issue.
Comments
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bisection points to #131699 |
workingjubilee
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Feb 14, 2025
…rors rework rigid alias handling Necessary for rust-lang#136824 if we treat coinductive cycles as errors as we otherwise don't emit an error for ```rust trait Overflow { type Assoc; } impl<T> Overflow for T { type Assoc = <T as Overflow>::Assoc; } ``` The important part is that we only add a `RigidAlias` candidate in cases where the alias is actually supposed to be rigid: - its trait bound has been proven via a `ParamEnv` or `ItemBound` candidate - it's one of the special builtin traits which have a blanket impl with a `default` assoc type This means that we now more explicitly control which aliases should rigid to avoid accidentally accepting cyclic aliases. This requires changes to diagnostics as we no longer enter an explicit `RigidAlias` candidate for `NormalizesTo` goals whose trait bound doesn't hold. To fix this I've modified the `BestObligation` visitor always ignore `RigidAlias` candidates and to instead manually check these requirements if there are no applicable candidates. I also removed the hack for handling `structurally_normalize_ty` failures. This fixes rust-lang#134905 as we no longer continue to use the `EvalCtxt` even though a nested goal failed. r? `@compiler-errors`
rust-timer
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Feb 14, 2025
Rollup merge of rust-lang#136863 - lcnr:treat-as-rigid, r=compiler-errors rework rigid alias handling Necessary for rust-lang#136824 if we treat coinductive cycles as errors as we otherwise don't emit an error for ```rust trait Overflow { type Assoc; } impl<T> Overflow for T { type Assoc = <T as Overflow>::Assoc; } ``` The important part is that we only add a `RigidAlias` candidate in cases where the alias is actually supposed to be rigid: - its trait bound has been proven via a `ParamEnv` or `ItemBound` candidate - it's one of the special builtin traits which have a blanket impl with a `default` assoc type This means that we now more explicitly control which aliases should rigid to avoid accidentally accepting cyclic aliases. This requires changes to diagnostics as we no longer enter an explicit `RigidAlias` candidate for `NormalizesTo` goals whose trait bound doesn't hold. To fix this I've modified the `BestObligation` visitor always ignore `RigidAlias` candidates and to instead manually check these requirements if there are no applicable candidates. I also removed the hack for handling `structurally_normalize_ty` failures. This fixes rust-lang#134905 as we no longer continue to use the `EvalCtxt` even though a nested goal failed. r? ``@compiler-errors``
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@rustbot label +F-specialization
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