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refactor(edmonds-karp): drop two unsafe Send impls the compiler already provides #820

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Merged
samueltardieu merged 1 commit into from
Sep 10, 2026
Merged

refactor(edmonds-karp): drop two unsafe Send impls the compiler already provides #820

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4 changes: 0 additions & 4 deletions src/directed/edmonds_karp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -352,8 +352,6 @@ pub struct SparseCapacity<C> {
residuals: BTreeMap<usize, BTreeMap<usize, C>>,
}

unsafe impl<C: Send> Send for SparseCapacity<C> {}

impl<C: Copy + Eq + Zero + Signed + Bounded + Ord> SparseCapacity<C> {
fn set_value(data: &mut BTreeMap<usize, BTreeMap<usize, C>>, from: usize, to: usize, value: C) {
let to_remove = {
Expand Down Expand Up @@ -479,8 +477,6 @@ pub struct DenseCapacity<C> {
flows: Matrix<C>,
}

unsafe impl<C: Send> Send for DenseCapacity<C> {}

impl<C: Copy + Zero + Signed + Ord + Bounded> EdmondsKarp<C> for DenseCapacity<C> {
fn new(size: usize, source: usize, sink: usize) -> Self {
assert!(source < size, "source is greater or equal than size");
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9 changes: 9 additions & 0 deletions tests/edmondskarp.rs
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Expand Up @@ -273,3 +273,12 @@ fn set_capacity_test() {
ek.augment();
residual_capacities_non_negative(&ek);
}

#[test]
fn capacities_are_send_without_an_unsafe_impl() {
// Every field of both types is `Send` when `C` is, so the compiler derives this on its
// own; the assertion is here so that a field which is not can never be added silently.
const fn assert_send<T: Send>() {}
assert_send::<DenseCapacity<i32>>();
assert_send::<SparseCapacity<i32>>();
}
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