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Rollup merge of #122437 - Nadrieril:no-after-max, r=compiler-errors

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pattern analysis: remove `MaybeInfiniteInt::JustAfterMax`

It was inherited from before half-open ranges, but it doesn't pull its weight anymore. We lose a tiny bit of diagnostic precision as can be seen in the test. I'm generally in favor of half-open ranges over explicit `x..=MAX` ranges anyway.
This commit is contained in:
Matthias Krüger 2024-03-13 20:01:57 +01:00 committed by GitHub
commit 5c2aa6dc6f
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4 changed files with 18 additions and 21 deletions
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13
compiler/rustc_pattern_analysis/src/constructor.rs
View File

@ -195,8 +195,6 @@ pub enum MaybeInfiniteInt {
/// Encoded value. DO NOT CONSTRUCT BY HAND; use `new_finite_{int,uint}`.
#[non_exhaustive]
Finite(u128),
/// The integer after `u128::MAX`. We need it to represent `x..=u128::MAX` as an exclusive range.
JustAfterMax,
PosInfinity,
}
@ -232,18 +230,18 @@ impl MaybeInfiniteInt {
pub fn minus_one(self) -> Option<Self> {
match self {
Finite(n) => n.checked_sub(1).map(Finite),
JustAfterMax => Some(Finite(u128::MAX)),
x => Some(x),
}
}
/// Note: this will not turn a finite value into an infinite one or vice-versa.
/// Note: this will turn `u128::MAX` into `PosInfinity`. This means `plus_one` and `minus_one`
/// are not strictly inverses, but that poses no problem in our use of them.
/// this will not turn a finite value into an infinite one or vice-versa.
pub fn plus_one(self) -> Option<Self> {
match self {
Finite(n) => match n.checked_add(1) {
Some(m) => Some(Finite(m)),
None => Some(JustAfterMax),
None => Some(PosInfinity),
},
JustAfterMax => None,
x => Some(x),
}
}
@ -277,8 +275,7 @@ impl IntRange {
}
/// Construct a range with these boundaries.
/// `lo` must not be `PosInfinity` or `JustAfterMax`. `hi` must not be `NegInfinity`.
/// If `end` is `Included`, `hi` must also not be `JustAfterMax`.
/// `lo` must not be `PosInfinity`. `hi` must not be `NegInfinity`.
#[inline]
pub fn from_range(lo: MaybeInfiniteInt, mut hi: MaybeInfiniteInt, end: RangeEnd) -> IntRange {
if end == RangeEnd::Included {

2
compiler/rustc_pattern_analysis/src/rustc.rs
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@ -706,7 +706,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
None => PatRangeBoundary::PosInfinity,
}
}
JustAfterMax | PosInfinity => PatRangeBoundary::PosInfinity,
PosInfinity => PatRangeBoundary::PosInfinity,
}
}

16
tests/ui/half-open-range-patterns/half-open-range-pats-exhaustive-fail.stderr
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@ -394,17 +394,17 @@ help: ensure that all possible cases are being handled by adding a match arm wit
LL | match $s { $($t)+ => {}, u128::MAX => todo!() }
| ++++++++++++++++++++++
error[E0004]: non-exhaustive patterns: `340282366920938463463374607431768211454_u128..=u128::MAX` not covered
error[E0004]: non-exhaustive patterns: `340282366920938463463374607431768211454_u128..` not covered
--> $DIR/half-open-range-pats-exhaustive-fail.rs:93:12
|
LL | m!(0, ..ALMOST_MAX);
| ^ pattern `340282366920938463463374607431768211454_u128..=u128::MAX` not covered
| ^ pattern `340282366920938463463374607431768211454_u128..` not covered
|
= note: the matched value is of type `u128`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL | match $s { $($t)+ => {}, 340282366920938463463374607431768211454_u128..=u128::MAX => todo!() }
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
LL | match $s { $($t)+ => {}, 340282366920938463463374607431768211454_u128.. => todo!() }
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
error[E0004]: non-exhaustive patterns: `0_u128` not covered
--> $DIR/half-open-range-pats-exhaustive-fail.rs:94:12
@ -754,17 +754,17 @@ help: ensure that all possible cases are being handled by adding a match arm wit
LL | match $s { $($t)+ => {}, i128::MAX => todo!() }
| ++++++++++++++++++++++
error[E0004]: non-exhaustive patterns: `170141183460469231731687303715884105726_i128..=i128::MAX` not covered
error[E0004]: non-exhaustive patterns: `170141183460469231731687303715884105726_i128..` not covered
--> $DIR/half-open-range-pats-exhaustive-fail.rs:161:12
|
LL | m!(0, ..ALMOST_MAX);
| ^ pattern `170141183460469231731687303715884105726_i128..=i128::MAX` not covered
| ^ pattern `170141183460469231731687303715884105726_i128..` not covered
|
= note: the matched value is of type `i128`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL | match $s { $($t)+ => {}, 170141183460469231731687303715884105726_i128..=i128::MAX => todo!() }
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
LL | match $s { $($t)+ => {}, 170141183460469231731687303715884105726_i128.. => todo!() }
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
error[E0004]: non-exhaustive patterns: `i128::MIN` not covered
--> $DIR/half-open-range-pats-exhaustive-fail.rs:162:12

8
tests/ui/pattern/usefulness/integer-ranges/exhaustiveness.stderr
View File

@ -107,17 +107,17 @@ help: ensure that all possible cases are being handled by adding a match arm wit
LL | match $s { $($t)+ => {}, u128::MAX => todo!() }
| ++++++++++++++++++++++
error[E0004]: non-exhaustive patterns: `5_u128..=u128::MAX` not covered
error[E0004]: non-exhaustive patterns: `5_u128..` not covered
--> $DIR/exhaustiveness.rs:61:8
|
LL | m!(0u128, 0..=4);
| ^^^^^ pattern `5_u128..=u128::MAX` not covered
| ^^^^^ pattern `5_u128..` not covered
|
= note: the matched value is of type `u128`
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
|
LL | match $s { $($t)+ => {}, 5_u128..=u128::MAX => todo!() }
| +++++++++++++++++++++++++++++++
LL | match $s { $($t)+ => {}, 5_u128.. => todo!() }
| +++++++++++++++++++++
error[E0004]: non-exhaustive patterns: `0_u128` not covered
--> $DIR/exhaustiveness.rs:62:8