ICE: Pattern mutability cap violated!
#136223
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A-patterns
Relating to patterns and pattern matching
C-bug
Category: This is a bug.
I-ICE
Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️
requires-debug-assertions
This issue requires a build of rustc or tooling with debug-assertions in some way
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matthiaskrgr
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matthiaskrgr
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Oops that's a bad regression 🙈 cc @dianne |
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This should be fixed by #135434. I wrote the original PR that introduced that before debug asserts were enabled by default, so I only noticed it later. It totally slipped my mind to make a separate PR once I did notice it. Sorry about that! In any case, the fix is already merged. I can't reproduce this. |
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Exactly, it was difficult for me to bisect this regression because some cases doesn't panic due to no debug assert 😸 |
Shunpoco
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Signed-off-by: Shunpoco <[email protected]>
Shunpoco
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Feb 7, 2025
Signed-off-by: Shunpoco <[email protected]>
workingjubilee
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…mutability-cap-violated, r=Nadrieril Add a comment pointing to ICE-136223 Fixes rust-lang#136223 ## Steps how the ICE happen This explanation is based on the test case `&Some(Some(x)) = &Some(&mut Some(0))`. The case should fail with E0596 error, but it catches the debug assertion instead. 1. For the first `&`: In check_pat_ref(), the value max_ref_mutbl becomes MutblCap::Not ([here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L2394-L2396)). Once max_ref_mutbl becomes Not, it will never be back to MutblCap::Mut. 2. For `&mut`: In peel_off_references(), because Some(x) doesn't have `&` nor `&mut`, `&mut` in `&mut Some(0)` is not consumed then default_binding_mode (def_br) becomes `ByRef::Yes(Mutability::Mut)` (around [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L519-L536)). This will be inherited to the next step. So this pattern has the mismatch between `def_br=Yes(Mut)` and `max_ref_mutbl=Not` now. 3. For the value `0`: Because of the step 2, the default_binding_mode is `Yes(Mut)`, but max_ref_mutbl is `Not` from the step 1. It causes the assertion error [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L427-L430). ## What this PR fixes Step 1 has happened from [this commit](rust-lang@e2f3ce9) by deleting `no_ref_mut_behind_and` from the if block. In my understanding, after RFC3627 is released, step 1 should happen not only 2024 edition but also other editions to track MutblCap value. But for now, it should not happen for non-2024 edition. So I put it back. NOTE: I think there is another solution - We should return an E0596 error in calc_default_binding_mode() instead of the debug assertion. Since the assertion is caused by the mismatch between `def_br = Yes(Mut)` and `max_ref_mutbl = Not`, but in my understanding this violation is the same as E0596. check_pat_ident() does returns E0596 by a similar reason [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L837-L856).
workingjubilee
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Feb 9, 2025
…mutability-cap-violated, r=Nadrieril Add a comment pointing to ICE-136223 Fixes rust-lang#136223 ## Steps how the ICE happen This explanation is based on the test case `&Some(Some(x)) = &Some(&mut Some(0))`. The case should fail with E0596 error, but it catches the debug assertion instead. 1. For the first `&`: In check_pat_ref(), the value max_ref_mutbl becomes MutblCap::Not ([here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L2394-L2396)). Once max_ref_mutbl becomes Not, it will never be back to MutblCap::Mut. 2. For `&mut`: In peel_off_references(), because Some(x) doesn't have `&` nor `&mut`, `&mut` in `&mut Some(0)` is not consumed then default_binding_mode (def_br) becomes `ByRef::Yes(Mutability::Mut)` (around [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L519-L536)). This will be inherited to the next step. So this pattern has the mismatch between `def_br=Yes(Mut)` and `max_ref_mutbl=Not` now. 3. For the value `0`: Because of the step 2, the default_binding_mode is `Yes(Mut)`, but max_ref_mutbl is `Not` from the step 1. It causes the assertion error [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L427-L430). ## What this PR fixes Step 1 has happened from [this commit](rust-lang@e2f3ce9) by deleting `no_ref_mut_behind_and` from the if block. In my understanding, after RFC3627 is released, step 1 should happen not only 2024 edition but also other editions to track MutblCap value. But for now, it should not happen for non-2024 edition. So I put it back. NOTE: I think there is another solution - We should return an E0596 error in calc_default_binding_mode() instead of the debug assertion. Since the assertion is caused by the mismatch between `def_br = Yes(Mut)` and `max_ref_mutbl = Not`, but in my understanding this violation is the same as E0596. check_pat_ident() does returns E0596 by a similar reason [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L837-L856).
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Feb 9, 2025
Rollup merge of rust-lang#136397 - Shunpoco:issue-136223-ICE-pattern-mutability-cap-violated, r=Nadrieril Add a comment pointing to ICE-136223 Fixes rust-lang#136223 ## Steps how the ICE happen This explanation is based on the test case `&Some(Some(x)) = &Some(&mut Some(0))`. The case should fail with E0596 error, but it catches the debug assertion instead. 1. For the first `&`: In check_pat_ref(), the value max_ref_mutbl becomes MutblCap::Not ([here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L2394-L2396)). Once max_ref_mutbl becomes Not, it will never be back to MutblCap::Mut. 2. For `&mut`: In peel_off_references(), because Some(x) doesn't have `&` nor `&mut`, `&mut` in `&mut Some(0)` is not consumed then default_binding_mode (def_br) becomes `ByRef::Yes(Mutability::Mut)` (around [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L519-L536)). This will be inherited to the next step. So this pattern has the mismatch between `def_br=Yes(Mut)` and `max_ref_mutbl=Not` now. 3. For the value `0`: Because of the step 2, the default_binding_mode is `Yes(Mut)`, but max_ref_mutbl is `Not` from the step 1. It causes the assertion error [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L427-L430). ## What this PR fixes Step 1 has happened from [this commit](rust-lang@e2f3ce9) by deleting `no_ref_mut_behind_and` from the if block. In my understanding, after RFC3627 is released, step 1 should happen not only 2024 edition but also other editions to track MutblCap value. But for now, it should not happen for non-2024 edition. So I put it back. NOTE: I think there is another solution - We should return an E0596 error in calc_default_binding_mode() instead of the debug assertion. Since the assertion is caused by the mismatch between `def_br = Yes(Mut)` and `max_ref_mutbl = Not`, but in my understanding this violation is the same as E0596. check_pat_ident() does returns E0596 by a similar reason [here](https://github.com/rust-lang/rust/blob/fdd1a3b02687817cea41f6bacae3d5fbed2b2cd0/compiler/rustc_hir_typeck/src/pat.rs#L837-L856).
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rust/compiler/rustc_hir_typeck/src/pat.rs
Lines 423 to 435 in fdd1a3b
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