do not attempt to prove unknowable goals#129896
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Seems reasonable to me. r=me if you'd like, with or without my one comment
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| // We also look for unknowable candidates. In case a goal is unknowable, there's | ||
| // always exactly 1 candidate. |
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It could be good to add an assert below for this.
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there are two possible asserts, both feel quite meh, so I didn't add any:
- if we found a coherence unknowable candidate, assert that there are no other candidates
- if we didn't find one, there is no coherence unknowable candidate in the remaining
candidates
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☔ The latest upstream changes (presumably #129915) made this pull request unmergeable. Please resolve the merge conflicts. |
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do not attempt to prove unknowable goals In case a goal is unknowable, we previously still checked all other possible ways to prove this goal, even though its final result is already guaranteed to be ambiguous. By ignoring all other candidates in that case we can avoid a lot of unnecessary work, fixing the performance regression in typenum found in rust-lang#121848. This is already the behavior in the old solver. This could in theory cause future-compatability issues as considering fewer goals unknowable may end up causing performance regressions/hangs. I am quite confident that this will not be an issue. r? `@compiler-errors`
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129706 (Rename dump of coroutine by-move-body to be more consistent, fix ICE in dump_mir) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header) - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks ) - rust-lang#128934 (Non-exhaustive structs may be empty) - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`) - rust-lang#129863 (update comment regarding TargetOptions.features) - rust-lang#129896 (do not attempt to prove unknowable goals) - rust-lang#129926 (Move `SanityCheck` and `MirPass`) - rust-lang#129928 (rustc_driver_impl: remove some old dead logic) - rust-lang#129930 (include 1.80.1 release notes on master) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#129896 - lcnr:bail-on-unknowable, r=jackh726 do not attempt to prove unknowable goals In case a goal is unknowable, we previously still checked all other possible ways to prove this goal, even though its final result is already guaranteed to be ambiguous. By ignoring all other candidates in that case we can avoid a lot of unnecessary work, fixing the performance regression in typenum found in rust-lang#121848. This is already the behavior in the old solver. This could in theory cause future-compatability issues as considering fewer goals unknowable may end up causing performance regressions/hangs. I am quite confident that this will not be an issue. r? ``@compiler-errors``
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In case a goal is unknowable, we previously still checked all other possible ways to prove this goal, even though its final result is already guaranteed to be ambiguous. By ignoring all other candidates in that case we can avoid a lot of unnecessary work, fixing the performance regression in typenum found in #121848.
This is already the behavior in the old solver. This could in theory cause future-compatability issues as considering fewer goals unknowable may end up causing performance regressions/hangs. I am quite confident that this will not be an issue.
r? @compiler-errors