match exhaustiveness diagnostics: show a trailing comma on singleton tuple consructors in witness patterns (and clean up a little) #145234
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By construction, `subpatterns` contains all fields in order. Witness patterns are constructed with all fields in order by `WitnessPat::wild_from_ctor` and `WitnessStack::apply_constructor`, and the order is preserved at `write_struct_like`'s call-site in `print_witness_pat`. It's thus no longer necessary to go looking for fields or handle missing fields.
rustbot added S-waiting-on-review | Some changes occurred in exhaustiveness checking cc @Nadrieril |
dianne commented Aug 10, 2025
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I haven't added a test specifically for singleton tuple witnesses since this test included them. I could add a separate test if it would be preferable, though, to make sure it's still tested even if this test changes.
| @bors r+ rollup |
bors added S-waiting-on-bors samueltardieu added a commit to samueltardieu/rust that referenced this pull request Aug 23, 2025
match exhaustiveness diagnostics: show a trailing comma on singleton tuple consructors in witness patterns (and clean up a little) Constructor patterns of type `(T,)` are written `(pat,)`, not `(pat)`. However, exhaustiveness/usefulness diagnostics would print them as `(pat)` when e.g. providing a witness of non-exhaustiveness and suggesting adding arms to make matches exhaustive; this would result in an error when applied. rust-analyzer already prints the trailing comma, so it doesn't need changing. This also includes some cleanup in the second commit, with justification in the commit message.
samueltardieu added a commit to samueltardieu/rust that referenced this pull request Aug 23, 2025
match exhaustiveness diagnostics: show a trailing comma on singleton tuple consructors in witness patterns (and clean up a little) Constructor patterns of type `(T,)` are written `(pat,)`, not `(pat)`. However, exhaustiveness/usefulness diagnostics would print them as `(pat)` when e.g. providing a witness of non-exhaustiveness and suggesting adding arms to make matches exhaustive; this would result in an error when applied. rust-analyzer already prints the trailing comma, so it doesn't need changing. This also includes some cleanup in the second commit, with justification in the commit message.
bors added a commit that referenced this pull request Aug 23, 2025
Rollup of 14 pull requests Successful merges: - #143898 (opt-dist: rebuild rustc when doing static LLVM builds) - #144452 (std/sys/fd: Relax `READ_LIMIT` on Darwin) - #145234 (match exhaustiveness diagnostics: show a trailing comma on singleton tuple consructors in witness patterns (and clean up a little)) - #145515 (Optimize `char::encode_utf8`) - #145540 (interpret/allocation: get_range on ProvenanceMap) - #145670 (port `sanitize` attribute to the new parsing infrastructure) - #145713 (next-solver: fix `feature(const_trait_impl)` bootstrap) - #145729 (Remove two duplicated crates) - #145744 (miri: also detect aliasing of in-place argument and return place) - #145774 (Remove default opts from config) - #145781 (Remove profile section from Clippy) - #145782 (rustdoc: make attributes render consistently) - #145787 (citool: cleanup `mismatched_lifetime_syntaxes` warnings) - #145791 (Fix ICE when validating transmuting ZST to inhabited enum) r? `@ghost` `@rustbot` modify labels: rollup
rust-timer added a commit that referenced this pull request Aug 24, 2025
Rollup merge of #145234 - dianne:1-tuple-witnesses, r=jackh726 match exhaustiveness diagnostics: show a trailing comma on singleton tuple consructors in witness patterns (and clean up a little) Constructor patterns of type `(T,)` are written `(pat,)`, not `(pat)`. However, exhaustiveness/usefulness diagnostics would print them as `(pat)` when e.g. providing a witness of non-exhaustiveness and suggesting adding arms to make matches exhaustive; this would result in an error when applied. rust-analyzer already prints the trailing comma, so it doesn't need changing. This also includes some cleanup in the second commit, with justification in the commit message.
| still in queue @bors r- |
bors added S-waiting-on-author github-actions bot pushed a commit to rust-lang/miri that referenced this pull request Aug 24, 2025
Rollup of 14 pull requests Successful merges: - rust-lang/rust#143898 (opt-dist: rebuild rustc when doing static LLVM builds) - rust-lang/rust#144452 (std/sys/fd: Relax `READ_LIMIT` on Darwin) - rust-lang/rust#145234 (match exhaustiveness diagnostics: show a trailing comma on singleton tuple consructors in witness patterns (and clean up a little)) - rust-lang/rust#145515 (Optimize `char::encode_utf8`) - rust-lang/rust#145540 (interpret/allocation: get_range on ProvenanceMap) - rust-lang/rust#145670 (port `sanitize` attribute to the new parsing infrastructure) - rust-lang/rust#145713 (next-solver: fix `feature(const_trait_impl)` bootstrap) - rust-lang/rust#145729 (Remove two duplicated crates) - rust-lang/rust#145744 (miri: also detect aliasing of in-place argument and return place) - rust-lang/rust#145774 (Remove default opts from config) - rust-lang/rust#145781 (Remove profile section from Clippy) - rust-lang/rust#145782 (rustdoc: make attributes render consistently) - rust-lang/rust#145787 (citool: cleanup `mismatched_lifetime_syntaxes` warnings) - rust-lang/rust#145791 (Fix ICE when validating transmuting ZST to inhabited enum) r? `@ghost` `@rustbot` modify labels: rollup
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Constructor patterns of type
(T,)are written(pat,), not(pat). However, exhaustiveness/usefulness diagnostics would print them as(pat)when e.g. providing a witness of non-exhaustiveness and suggesting adding arms to make matches exhaustive; this would result in an error when applied.rust-analyzer already prints the trailing comma, so it doesn't need changing.
This also includes some cleanup in the second commit, with justification in the commit message.