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Deny specializing items not in the parent impl #64564

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Merged
merged 8 commits into from
Oct 6, 2019
Merged

Deny specializing items not in the parent impl #64564

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2cd5030
Deny specializing items not in the parent impl
jonas-schievink Sep 17, 2019
55277d4
Add comment to `Type` and `OpaqueTy` match
jonas-schievink Sep 18, 2019
02f36e5
Hide the `Iterator` specialization behind a trait
jonas-schievink Sep 18, 2019
9aaef06
Fix the bootstrap
jonas-schievink Sep 18, 2019
a0cf531
Test that we get the proper errors
jonas-schievink Sep 18, 2019
98f02b2
Pacify tidy
jonas-schievink Sep 18, 2019
33d23cd
Extend test and fix nits
jonas-schievink Sep 18, 2019
47f89e7
Rename the test
jonas-schievink Sep 18, 2019
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Hide the Iterator specialization behind a trait
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@jonas-schievink
jonas-schievink committed Oct 5, 2019
commit 02f36e52a656f1baa717538e18ae96137cbc83f9
27 changes: 22 additions & 5 deletions src/liballoc/boxed.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -871,16 +871,33 @@ impl<I: Iterator + ?Sized> Iterator for Box<I> {
fn nth(&mut self, n: usize) -> Option<I::Item> {
(**self).nth(n)
}
fn last(self) -> Option<I::Item> {
BoxIter::last(self)
}
}

trait BoxIter {
type Item;
fn last(self) -> Option<Self::Item>;
}

impl<I: Iterator + ?Sized> BoxIter for Box<I> {
type Item = I::Item;
default fn last(self) -> Option<I::Item> {
let mut last = None;
for x in self { last = Some(x); }
last
#[inline]
fn some<T>(_: Option<T>, x: T) -> Option<T> {
Some(x)
}

self.fold(None, some)
}
}

/// Specialization for sized `I`s that uses `I`s implementation of `last()`
/// instead of the default.
#[stable(feature = "rust1", since = "1.0.0")]
impl<I: Iterator + Sized> Iterator for Box<I> {
fn last(self) -> Option<I::Item> where I: Sized {
impl<I: Iterator> BoxIter for Box<I> {
fn last(self) -> Option<I::Item> {
(*self).last()
}
}
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