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Rollup merge of #72902 - cuviper:fuse-covariant, r=nikomatsakis

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Add a test to ensure Fuse stays covariant

When #70502 attempted to specialize the data types in `Fuse`, one of the problems we found was that it broke variance. This was also realized when `Fuse` was first added, https://github.com/rust-lang/rust/pull/35656#discussion-diff-74995079, but now this PR adds a test so we don't forget again.
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Dylan DPC 2020-06-03 02:39:07 +02:00 committed by GitHub
commit 0050b8817b
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1 changed files with 3 additions and 2 deletions
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src/test/ui/variance-iterators-in-libcore.rs
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@ -1,9 +1,10 @@
// run-pass
#![allow(warnings)]
#![allow(dead_code)]
use std::iter::Zip;
use std::iter::{Fuse, Zip};
fn fuse_covariant<'a, I>(iter: Fuse<&'static I>) -> Fuse<&'a I> { iter }
fn zip_covariant<'a, A, B>(iter: Zip<&'static A, &'static B>) -> Zip<&'a A, &'a B> { iter }
fn main() { }