Emit delayed bug during wfck for stranded opaque #148173
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Rollup merge of #148173 - tiif:fix-opaque-ice, r=BoxyUwU Emit delayed bug during wfck for stranded opaque Fixes rust-lang/trait-system-refactor-initiative#235 ## Problem The fundamental issue here is ``OpaqueTypeCollector`` operates on ``rustc_middle::Ty``, but ``check_type_wf`` operates on HIR. Since [check_type_wf](https://github.com/rust-lang/rust/blob/2f7620a5ccfea7d59d1f500e2a2e59cf1c867a1b/compiler/rustc_hir_analysis/src/check/wfcheck.rs#L2262) operates on HIR, it can see the stranded opaque and tries to infer it's hidden type. But ``OpaqueTypeCollector`` operates on ``rustc_middle::Ty``, so the ``OpaqueTypeCollector`` can no longer see a stranded opaque, hence its hidden type could not be inferred. As a result, the tests ICE'ed at https://github.com/rust-lang/rust/blob/34a8c7368c84fc699fc83a8851a02f93fd655931/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs#L253 ## Proposed solution This PR detects stranded opaque types during wf check and emit a delayed bug for it. ## Alternative solution `@BoxyUwU` and I had considered rewriting ``OpaqueTypeCollector`` to be a HIR visitor instead of a ``rustc_middle::Ty`` visitor, but we believe a HIR-based ``OpaqueTypeCollector`` will not work and might not worth the cost of rewriting. ## Acknowledgement This PR is a joint effort with `@BoxyUwU` :3
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Fixes rust-lang/trait-system-refactor-initiative#235
Problem
The fundamental issue here is
OpaqueTypeCollectoroperates onrustc_middle::Ty, butcheck_type_wfoperates on HIR.Since check_type_wf operates on HIR, it can see the stranded opaque and tries to infer it's hidden type. But
OpaqueTypeCollectoroperates onrustc_middle::Ty, so theOpaqueTypeCollectorcan no longer see a stranded opaque, hence its hidden type could not be inferred.As a result, the tests ICE'ed at
rust/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
Line 253 in 34a8c73
Proposed solution
This PR detects stranded opaque types during wf check and emit a delayed bug for it.
Alternative solution
@BoxyUwU and I had considered rewriting
OpaqueTypeCollectorto be a HIR visitor instead of arustc_middle::Tyvisitor, but we believe a HIR-basedOpaqueTypeCollectorwill not work and might not worth the cost of rewriting.Acknowledgement
This PR is a joint effort with @BoxyUwU :3