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bors 1a086e49f1 Auto merge of #118796 - Nadrieril:fix-exponential-id-match-2, r=cjgillot 
Exhaustiveness: Improve complexity on some wide matches

https://github.com/rust-lang/rust/issues/118437 revealed an exponential case in exhaustiveness checking. While [exponential cases are unavoidable](https://compilercrim.es/rust-np/), this one only showed up after my https://github.com/rust-lang/rust/pull/117611 rewrite of the algorithm. I remember anticipating a case like this and dismissing it as unrealistic, but here we are :').

The tricky match is as follows:
```rust
match command {
    BaseCommand { field01: true, .. } => {}
    BaseCommand { field02: true, .. } => {}
    BaseCommand { field03: true, .. } => {}
    BaseCommand { field04: true, .. } => {}
    BaseCommand { field05: true, .. } => {}
    BaseCommand { field06: true, .. } => {}
    BaseCommand { field07: true, .. } => {}
    BaseCommand { field08: true, .. } => {}
    BaseCommand { field09: true, .. } => {}
    BaseCommand { field10: true, .. } => {}
    // ...20 more of the same

    _ => {}
}
```

To fix this, this PR formalizes a concept of "relevancy" (naming is hard) that was already used to decide what patterns to report. Now we track it for every row, which in wide matches like the above can drastically cut on the number of cases we explore. After this fix, the above match is checked with linear-many cases instead of exponentially-many.

Fixes https://github.com/rust-lang/rust/issues/118437

r? `@cjgillot`
2023-12-24 14:40:36 +00:00
..
auxiliary Add note when matching on nested non-exhaustive enums 2023-08-28 14:50:32 +08:00
integer-ranges Remove the precise_pointer_size_matching feature gate 2023-12-04 11:56:21 +01:00
always-inhabited-union-ref.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
always-inhabited-union-ref.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
conflicting_bindings.rs Always do all the pattern checks 2023-11-02 03:19:19 +01:00
conflicting_bindings.stderr Always do all the pattern checks 2023-11-02 03:19:19 +01:00
const-partial_eq-fallback-ice.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
const-partial_eq-fallback-ice.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
const-pat-ice.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
const-private-fields.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
consts-opaque.rs make pointer_structural_match warn-by-default 2023-10-28 17:02:18 +02:00
consts-opaque.stderr make pointer_structural_match warn-by-default 2023-10-28 17:02:18 +02:00
deny-irrefutable-let-patterns.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
deny-irrefutable-let-patterns.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
doc-hidden-fields.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
doc-hidden-fields.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
doc-hidden-non-exhaustive.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
doc-hidden-non-exhaustive.stderr Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
empty-match-check-notes.exhaustive_patterns.stderr Test empty types better 2023-12-09 00:39:59 +01:00
empty-match-check-notes.normal.stderr Test empty types better 2023-12-09 00:39:59 +01:00
empty-match-check-notes.rs Test empty types better 2023-12-09 00:39:59 +01:00
empty-match.exhaustive_patterns.stderr Test empty types better 2023-12-09 00:39:59 +01:00
empty-match.normal.stderr Test empty types better 2023-12-09 00:39:59 +01:00
empty-match.rs Test empty types better 2023-12-09 00:39:59 +01:00
empty-types.exhaustive_patterns.stderr Don't warn an empty pattern unreachable if we're not sure the data is valid 2023-12-09 00:44:49 +01:00
empty-types.normal.stderr Don't warn an empty pattern unreachable if we're not sure the data is valid 2023-12-09 00:44:49 +01:00
empty-types.rs Don't warn an empty pattern unreachable if we're not sure the data is valid 2023-12-09 00:44:49 +01:00
floats.rs Evaluate float consts eagerly 2023-10-01 00:00:37 +02:00
floats.stderr Evaluate float consts eagerly 2023-10-01 00:00:37 +02:00
guards.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
guards.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
impl-trait.rs Reveal empty opaques in depth 2023-12-23 14:59:12 +01:00
impl-trait.stderr Reveal empty opaques in depth 2023-12-23 14:59:12 +01:00
irrefutable-let-patterns.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
irrefutable-unit.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-2111.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-2111.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-3096-1.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-3096-1.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-3096-2.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-3096-2.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-3601.rs Keep rows with guards in the matrix 2023-11-22 03:25:15 +01:00
issue-3601.stderr Auto merge of #117611 - Nadrieril:linear-pass-take-4, r=cjgillot 2023-11-26 00:14:14 +00:00
issue-4321.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-4321.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-12116.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-12116.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-12369.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-12369.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-13727.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-13727.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-15129.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-15129.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-30240-b.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-30240-b.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-30240-rpass.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-30240.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-30240.stderr Improve clarity of diagnostic message on non-exhaustive matches 2023-09-03 19:55:11 +08:00
issue-31221.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-31221.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-31561.rs Migrate pattern matching 2023-01-11 14:40:02 -08:00
issue-31561.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-35609.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-35609.stderr Tweak diagnostic for consistency 2023-11-02 03:19:19 +01:00
issue-39362.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-39362.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-40221.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-40221.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-50900.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-50900.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-53820-slice-pattern-large-array.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-56379.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-56379.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-57472.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-57472.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-65413-constants-and-slices-exhaustiveness.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-66501.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-71930-type-of-match-scrutinee.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-72377.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-72377.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-72476-and-89393-associated-type.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-78123-non-exhaustive-reference.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-78123-non-exhaustive-reference.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-78549-ref-pat-and-str.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-80501-or-pat-and-macro.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-82772-match-box-as-struct.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-82772-match-box-as-struct.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-85222-types-containing-non-exhaustive-types.rs Match usize/isize exhaustively 2023-10-27 19:56:12 +02:00
issue-85222-types-containing-non-exhaustive-types.stderr Remove the precise_pointer_size_matching feature gate 2023-12-04 11:56:21 +01:00
issue-88747.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
issue-105479-str-non-exhaustiveness.rs Improve clarity of diagnostic message on non-exhaustive matches 2023-09-03 19:55:11 +08:00
issue-105479-str-non-exhaustiveness.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
issue-118437-exponential-time-on-diagonal-match.rs Improve performance on wide matches 2023-12-23 13:11:38 +01:00
match-arm-statics-2.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-arm-statics-2.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-arm-statics.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-arm-statics.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-byte-array-patterns-2.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-byte-array-patterns-2.stderr Perform match checking on THIR. 2023-04-03 15:59:21 +00:00
match-byte-array-patterns.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-byte-array-patterns.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-non-exhaustive.rs add note for non-exhaustive matches with guards 2023-06-28 01:51:53 -04:00
match-non-exhaustive.stderr Keep rows with guards in the matrix 2023-11-22 03:25:15 +01:00
match-privately-empty.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-privately-empty.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
match-ref-ice.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-ref-ice.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
match-slice-patterns.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-slice-patterns.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
match-vec-fixed.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-vec-fixed.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-vec-unreachable.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
match-vec-unreachable.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
nested-exhaustive-match.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
nested-non-exhaustive-enums.rs Add note when matching on nested non-exhaustive enums 2023-08-28 14:50:32 +08:00
nested-non-exhaustive-enums.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
non-exhaustive-defined-here.rs Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
non-exhaustive-defined-here.stderr Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
non-exhaustive-match-nested.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
non-exhaustive-match-nested.stderr Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
non-exhaustive-match.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
non-exhaustive-match.stderr Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
non-exhaustive-pattern-witness.rs Match usize/isize exhaustively 2023-10-27 19:56:12 +02:00
non-exhaustive-pattern-witness.stderr Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
refutable-pattern-errors.rs Match usize/isize exhaustively 2023-10-27 19:56:12 +02:00
refutable-pattern-errors.stderr Match usize/isize exhaustively 2023-10-27 19:56:12 +02:00
refutable-pattern-in-fn-arg.rs Match usize/isize exhaustively 2023-10-27 19:56:12 +02:00
refutable-pattern-in-fn-arg.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
slice-pattern-const-2.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-pattern-const-2.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-pattern-const-3.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-pattern-const-3.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-pattern-const.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-pattern-const.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-patterns-exhaustiveness.rs Keep rows with guards in the matrix 2023-11-22 03:25:15 +01:00
slice-patterns-exhaustiveness.stderr Keep rows with guards in the matrix 2023-11-22 03:25:15 +01:00
slice-patterns-irrefutable.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-patterns-reachability.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice-patterns-reachability.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
slice_of_empty.rs Don't warn an empty pattern unreachable if we're not sure the data is valid 2023-12-09 00:44:49 +01:00
slice_of_empty.stderr Don't warn an empty pattern unreachable if we're not sure the data is valid 2023-12-09 00:44:49 +01:00
stable-gated-fields.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
stable-gated-fields.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
stable-gated-patterns.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
stable-gated-patterns.stderr Tweak spans for "adt defined here" note 2023-11-03 18:26:16 +01:00
struct-like-enum-nonexhaustive.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
struct-like-enum-nonexhaustive.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
struct-pattern-match-useless.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
struct-pattern-match-useless.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
top-level-alternation.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
top-level-alternation.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
tuple-struct-nonexhaustive.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
tuple-struct-nonexhaustive.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00
type_polymorphic_byte_str_literals.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
type_polymorphic_byte_str_literals.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
uninhabited.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
unstable-gated-fields.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
unstable-gated-fields.stderr Move /src/test to /tests 2023-01-11 09:32:08 +00:00
unstable-gated-patterns.rs Move /src/test to /tests 2023-01-11 09:32:08 +00:00
unstable-gated-patterns.stderr Show number in error message even for one error 2023-11-24 19:15:52 +01:00