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Auto merge of #7951 - mikerite:matches-20211109, r=llogiq

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`match_overlapping_arm` refactoring

The main purpose of this pull request is to remove the unneeded and scary `unimplented!()` in the `match_arm_overlapping` code.

The rest is gratuitous refactoring.

changelog: none
This commit is contained in:
bors 2021-11-09 19:28:48 +00:00
commit 93f13d532f
1 changed files with 56 additions and 76 deletions
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132
clippy_lints/src/matches.rs
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@ -33,7 +33,6 @@ use rustc_span::source_map::{Span, Spanned};
use rustc_span::sym;
use std::cmp::Ordering;
use std::collections::hash_map::Entry;
use std::ops::Bound;
declare_clippy_lint! {
/// ### What it does
@ -1596,27 +1595,27 @@ fn opt_parent_let<'a>(cx: &LateContext<'a>, ex: &Expr<'a>) -> Option<&'a Local<'
None
}
/// Gets all arms that are unbounded `PatRange`s.
/// Gets the ranges for each range pattern arm. Applies `ty` bounds for open ranges.
fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>) -> Vec<SpannedRange<FullInt>> {
arms.iter()
.filter_map(|arm| {
if let Arm { pat, guard: None, .. } = *arm {
if let PatKind::Range(ref lhs, ref rhs, range_end) = pat.kind {
let lhs = match lhs {
let lhs_const = match lhs {
Some(lhs) => constant(cx, cx.typeck_results(), lhs)?.0,
None => miri_to_const(ty.numeric_min_val(cx.tcx)?)?,
};
let rhs = match rhs {
let rhs_const = match rhs {
Some(rhs) => constant(cx, cx.typeck_results(), rhs)?.0,
None => miri_to_const(ty.numeric_max_val(cx.tcx)?)?,
};
let lhs_val = lhs.int_value(cx, ty)?;
let rhs_val = rhs.int_value(cx, ty)?;
let lhs_val = lhs_const.int_value(cx, ty)?;
let rhs_val = rhs_const.int_value(cx, ty)?;
let rhs_bound = match range_end {
RangeEnd::Included => Bound::Included(rhs_val),
RangeEnd::Excluded => Bound::Excluded(rhs_val),
RangeEnd::Included => EndBound::Included(rhs_val),
RangeEnd::Excluded => EndBound::Excluded(rhs_val),
};
return Some(SpannedRange {
span: pat.span,
@ -1628,7 +1627,7 @@ fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>)
let value = constant_full_int(cx, cx.typeck_results(), value)?;
return Some(SpannedRange {
span: pat.span,
node: (value, Bound::Included(value)),
node: (value, EndBound::Included(value)),
});
}
}
@ -1637,10 +1636,16 @@ fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>)
.collect()
}
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum EndBound<T> {
Included(T),
Excluded(T),
}
#[derive(Debug, Eq, PartialEq)]
pub struct SpannedRange<T> {
struct SpannedRange<T> {
pub span: Span,
pub node: (T, Bound<T>),
pub node: (T, EndBound<T>),
}
// Checks if arm has the form `None => None`
@ -1689,87 +1694,62 @@ where
ref_count > 1
}
pub fn overlapping<T>(ranges: &[SpannedRange<T>]) -> Option<(&SpannedRange<T>, &SpannedRange<T>)>
fn overlapping<T>(ranges: &[SpannedRange<T>]) -> Option<(&SpannedRange<T>, &SpannedRange<T>)>
where
T: Copy + Ord,
{
#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
enum BoundKind {
EndExcluded,
Start,
EndIncluded,
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum Kind<'a, T> {
Start(T, &'a SpannedRange<T>),
End(Bound<T>, &'a SpannedRange<T>),
}
struct RangeBound<'a, T>(T, BoundKind, &'a SpannedRange<T>);
impl<'a, T: Copy> Kind<'a, T> {
fn value(self) -> Bound<T> {
match self {
Kind::Start(t, _) => Bound::Included(t),
Kind::End(t, _) => t,
}
}
}
impl<'a, T: Copy + Ord> PartialOrd for Kind<'a, T> {
impl<'a, T: Copy + Ord> PartialOrd for RangeBound<'a, T> {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl<'a, T: Copy + Ord> Ord for Kind<'a, T> {
fn cmp(&self, other: &Self) -> Ordering {
match (self.value(), other.value()) {
(Bound::Included(a), Bound::Included(b)) | (Bound::Excluded(a), Bound::Excluded(b)) => {
let value_cmp = a.cmp(&b);
// In the case of ties, starts come before ends
if value_cmp == Ordering::Equal {
match (self, other) {
(Kind::Start(..), Kind::End(..)) => Ordering::Less,
(Kind::End(..), Kind::Start(..)) => Ordering::Greater,
_ => Ordering::Equal,
}
} else {
value_cmp
}
},
// Range patterns cannot be unbounded (yet)
(Bound::Unbounded, _) | (_, Bound::Unbounded) => unimplemented!(),
(Bound::Included(a), Bound::Excluded(b)) => match a.cmp(&b) {
Ordering::Equal => Ordering::Greater,
other => other,
},
(Bound::Excluded(a), Bound::Included(b)) => match a.cmp(&b) {
Ordering::Equal => Ordering::Less,
other => other,
},
}
impl<'a, T: Copy + Ord> Ord for RangeBound<'a, T> {
fn cmp(&self, RangeBound(other_value, other_kind, _): &Self) -> Ordering {
let RangeBound(self_value, self_kind, _) = *self;
(self_value, self_kind).cmp(&(*other_value, *other_kind))
}
}
let mut values = Vec::with_capacity(2 * ranges.len());
for r in ranges {
values.push(Kind::Start(r.node.0, r));
values.push(Kind::End(r.node.1, r));
for r @ SpannedRange { node: (start, end), .. } in ranges {
values.push(RangeBound(*start, BoundKind::Start, r));
values.push(match end {
EndBound::Excluded(val) => RangeBound(*val, BoundKind::EndExcluded, r),
EndBound::Included(val) => RangeBound(*val, BoundKind::EndIncluded, r),
});
}
values.sort();
let mut started = vec![];
for value in values {
match value {
Kind::Start(_, r) => started.push(r),
Kind::End(_, er) => {
for RangeBound(_, kind, range) in values {
match kind {
BoundKind::Start => started.push(range),
BoundKind::EndExcluded | BoundKind::EndIncluded => {
let mut overlap = None;
while let Some(sr) = started.pop() {
if sr == er {
while let Some(last_started) = started.pop() {
if last_started == range {
break;
}
overlap = Some(sr);
overlap = Some(last_started);
}
if let Some(sr) = overlap {
return Some((er, sr));
if let Some(first_overlapping) = overlap {
return Some((range, first_overlapping));
}
},
}
@ -2227,29 +2207,29 @@ fn test_overlapping() {
};
assert_eq!(None, overlapping::<u8>(&[]));
assert_eq!(None, overlapping(&[sp(1, Bound::Included(4))]));
assert_eq!(None, overlapping(&[sp(1, EndBound::Included(4))]));
assert_eq!(
None,
overlapping(&[sp(1, Bound::Included(4)), sp(5, Bound::Included(6))])
overlapping(&[sp(1, EndBound::Included(4)), sp(5, EndBound::Included(6))])
);
assert_eq!(
None,
overlapping(&[
sp(1, Bound::Included(4)),
sp(5, Bound::Included(6)),
sp(10, Bound::Included(11))
sp(1, EndBound::Included(4)),
sp(5, EndBound::Included(6)),
sp(10, EndBound::Included(11))
],)
);
assert_eq!(
Some((&sp(1, Bound::Included(4)), &sp(3, Bound::Included(6)))),
overlapping(&[sp(1, Bound::Included(4)), sp(3, Bound::Included(6))])
Some((&sp(1, EndBound::Included(4)), &sp(3, EndBound::Included(6)))),
overlapping(&[sp(1, EndBound::Included(4)), sp(3, EndBound::Included(6))])
);
assert_eq!(
Some((&sp(5, Bound::Included(6)), &sp(6, Bound::Included(11)))),
Some((&sp(5, EndBound::Included(6)), &sp(6, EndBound::Included(11)))),
overlapping(&[
sp(1, Bound::Included(4)),
sp(5, Bound::Included(6)),
sp(6, Bound::Included(11))
sp(1, EndBound::Included(4)),
sp(5, EndBound::Included(6)),
sp(6, EndBound::Included(11))
],)
);
}