mirror of https://github.com/rust-lang/rust
21 lines
504 B
Rust
21 lines
504 B
Rust
//@ run-pass
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// Test that vec is now covariant in its argument type.
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#![allow(dead_code)]
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fn foo<'a,'b>(v1: Vec<&'a i32>, v2: Vec<&'b i32>) -> i32 {
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bar(v1, v2).cloned().unwrap_or(0) // only type checks if we can intersect 'a and 'b
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}
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fn bar<'c>(v1: Vec<&'c i32>, v2: Vec<&'c i32>) -> Option<&'c i32> {
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v1.get(0).cloned().or_else(|| v2.get(0).cloned())
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}
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fn main() {
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let x = 22;
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let y = 44;
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assert_eq!(foo(vec![&x], vec![&y]), 22);
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assert_eq!(foo(vec![&y], vec![&x]), 44);
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}
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