fix: Panic when trait solver re-enters itself - #23367
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ChayimFriedman2 merged 1 commit intoSep 15, 2026
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rust-analyzer would panic when the trait solver called itself, which can happen during const evaluation. rustc has the same function, but doesn't panic, so just copy the rustc implementation: https://github.com/rust-lang/rust/blob/5392d2f545c6836dc79f209bcc14ac7179dbc4f2/compiler/rustc_middle/src/ty/context/impl_interner.rs#L155 This caused SCIP crashes on the dudykr/stc, renegade-fi/renegade, and tikv/tikv GitHub repositories, so would presumably cause LSP crashes too. The linked trait-system-refactor-initiative issue has a repro, but for reference I minimised a repro independently: trait Tr { const N: usize; } struct A<const N: usize>; impl<const N: usize> Tr for A<N> { const N: usize = N; } const fn k<T: Tr>() -> usize { T::N } struct B<const N: usize>; impl<const N: usize> Tr for B<N> where A<{ k::<A<3>>() }>: Tr { const N: usize = 0; } fn need<T: Tr>() {} fn f() { need::<B<1>>(); } Since this is strictly removing a panic and copying rustc, I haven't added a unit test with this. AI disclosure: Triaged and minimised with help by an LLM, but commit message and final code by me.
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rust-analyzer would panic when the trait solver called itself, which can happen during const evaluation.
rustc has the same function, but doesn't panic, so just copy the rustc implementation:
https://github.com/rust-lang/rust/blob/5392d2f545c6836dc79f209bcc14ac7179dbc4f2/compiler/rustc_middle/src/ty/context/impl_interner.rs#L155
This caused SCIP crashes on the dudykr/stc, renegade-fi/renegade, and tikv/tikv GitHub repositories, so would presumably cause LSP crashes too.
The linked trait-system-refactor-initiative issue has a repro, but for reference I minimised a repro independently:
Since this is strictly removing a panic and copying rustc, I haven't added a unit test with this.
AI disclosure: Triaged and minimised with help by an LLM, but commit message and final code by me.