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Stabilize min_exhaustive_patterns

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Nadrieril
2024-03-20 19:24:42 +01:00
parent 19469cb536
commit cd40769c02
10 changed files with 19 additions and 39 deletions
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19
compiler/rustc_pattern_analysis/src/usefulness.rs
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@@ -543,13 +543,11 @@
//! recurse into subpatterns. That second part is done through [`PlaceValidity`], most notably
//! [`PlaceValidity::specialize`].
//!
//! Having said all that, in practice we don't fully follow what's been presented in this section.
//! Let's call "toplevel exception" the case where the match scrutinee itself has type `!` or
//! `EmptyEnum`. First, on stable rust, we require `_` patterns for empty types in all cases apart
//! from the toplevel exception. The `exhaustive_patterns` and `min_exaustive_patterns` allow
//! omitting patterns in the cases described above. There's a final detail: in the toplevel
//! exception or with the `exhaustive_patterns` feature, we ignore place validity when checking
//! whether a pattern is required for exhaustiveness. I (Nadrieril) hope to deprecate this behavior.
//! Having said all that, we don't fully follow what's been presented in this section. For
//! backwards-compatibility, we ignore place validity when checking whether a pattern is required
//! for exhaustiveness in two cases: when the `exhaustive_patterns` feature gate is on, or when the
//! match scrutinee itself has type `!` or `EmptyEnum`. I (Nadrieril) hope to deprecate this
//! exception.
//!
//!
//!
@@ -953,13 +951,10 @@ impl<Cx: PatCx> PlaceInfo<Cx> {
self.is_scrutinee && matches!(ctors_for_ty, ConstructorSet::NoConstructors);
// Whether empty patterns are counted as useful or not. We only warn an empty arm unreachable if
// it is guaranteed unreachable by the opsem (i.e. if the place is `known_valid`).
let empty_arms_are_unreachable = self.validity.is_known_valid()
&& (is_toplevel_exception
|| cx.is_exhaustive_patterns_feature_on()
|| cx.is_min_exhaustive_patterns_feature_on());
let empty_arms_are_unreachable = self.validity.is_known_valid();
// Whether empty patterns can be omitted for exhaustiveness. We ignore place validity in the
// toplevel exception and `exhaustive_patterns` cases for backwards compatibility.
let can_omit_empty_arms = empty_arms_are_unreachable
let can_omit_empty_arms = self.validity.is_known_valid()
|| is_toplevel_exception
|| cx.is_exhaustive_patterns_feature_on();