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Simplify use of ValidityConstraint

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We had reached a point where the shenanigans about omitting empty arms
are unnecessary.
This commit is contained in:
Nadrieril 2024-01-10 22:42:23 +01:00
parent 2ad780eaf0
commit bf913ad0ae
1 changed files with 4 additions and 23 deletions
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27
compiler/rustc_pattern_analysis/src/usefulness.rs
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@ -768,9 +768,6 @@ impl<'a, Cx: TypeCx> PlaceCtxt<'a, Cx> {
pub enum ValidityConstraint {
ValidOnly,
MaybeInvalid,
/// Option for backwards compatibility: the place is not known to be valid but we allow omitting
/// `useful && !reachable` arms anyway.
MaybeInvalidButAllowOmittingArms,
}
impl ValidityConstraint {
@ -778,20 +775,9 @@ impl ValidityConstraint {
if is_valid_only { ValidOnly } else { MaybeInvalid }
}
fn allow_omitting_side_effecting_arms(self) -> Self {
match self {
MaybeInvalid | MaybeInvalidButAllowOmittingArms => MaybeInvalidButAllowOmittingArms,
// There are no side-effecting empty arms here, nothing to do.
ValidOnly => ValidOnly,
}
}
fn is_known_valid(self) -> bool {
matches!(self, ValidOnly)
}
fn allows_omitting_empty_arms(self) -> bool {
matches!(self, ValidOnly | MaybeInvalidButAllowOmittingArms)
}
/// If the place has validity given by `self` and we read that the value at the place has
/// constructor `ctor`, this computes what we can assume about the validity of the constructor
@ -814,7 +800,7 @@ impl fmt::Display for ValidityConstraint {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let s = match self {
ValidOnly => "✓",
MaybeInvalid | MaybeInvalidButAllowOmittingArms => "?",
MaybeInvalid => "?",
};
write!(f, "{s}")
}
@ -1460,8 +1446,6 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
// Whether the place/column we are inspecting is known to contain valid data.
let place_validity = matrix.place_validity[0];
// For backwards compability we allow omitting some empty arms that we ideally shouldn't.
let place_validity = place_validity.allow_omitting_side_effecting_arms();
// Analyze the constructors present in this column.
let ctors = matrix.heads().map(|p| p.ctor());
@ -1486,12 +1470,9 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
// Whether we should report "Enum::A and Enum::C are missing" or "_ is missing".
let report_individual_missing_ctors = always_report_all || !all_missing;
// Which constructors are considered missing. We ensure that `!missing_ctors.is_empty() =>
// split_ctors.contains(Missing)`. The converse usually holds except in the
// `MaybeInvalidButAllowOmittingArms` backwards-compatibility case.
let mut missing_ctors = split_set.missing;
if !place_validity.allows_omitting_empty_arms() {
missing_ctors.extend(split_set.missing_empty);
}
// split_ctors.contains(Missing)`. The converse usually holds except when
// `!place_validity.is_known_valid()`.
let missing_ctors = split_set.missing;
let mut ret = WitnessMatrix::empty();
for ctor in split_ctors {