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Merged
eholk merged 1 commit into from
Oct 25, 2022
Merged

Add comment explaining why we don't impl From<F> for Stackfuture #19

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9 changes: 9 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,15 @@ impl<'a, T, const STACK_SIZE: usize> StackFuture<'a, T, { STACK_SIZE }> {
where
F: Future<Output = T> + Send + 'a, // the bounds here should match those in the _phantom field
{
// Ideally we would provide this as:
//
// impl<'a, F, const STACK_SIZE: usize> From<F> for StackFuture<'a, F::Output, { STACK_SIZE }>
// where
// F: Future + Send + 'a
//
// However, libcore provides a blanket `impl<T> From<T> for T`, and since `StackFuture: Future`,
// both impls end up being applicable to do `From<StackFuture> for StackFuture`.

Self::try_from(future).unwrap_or_else(|f| {
match (Self::has_alignment_for_val(&f), Self::has_space_for_val(&f)) {
(false, false) => panic!(
Expand Down