39 lines
1.3 KiB
Rust
39 lines
1.3 KiB
Rust
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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Test that a type which is covariant with respect to its region
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// parameter yields an error when used in a contravariant way.
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//
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// Note: see variance-regions-*.rs for the tests that check that the
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// variance inference works in the first place.
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// `S` is contravariant with respect to both parameters.
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struct S<'a, 'b> {
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f: &'a int,
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g: &'b int,
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}
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fn use_<'short,'long>(c: S<'long, 'short>,
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s: &'short int,
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l: &'long int,
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_where:Option<&'short &'long ()>) {
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let _: S<'long, 'short> = c; // OK
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let _: S<'short, 'short> = c; // OK
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// Test whether S<_,'short> <: S<_,'long>. Since
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// 'short <= 'long, this would be true if the Contravariant type were
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// covariant with respect to its parameter 'a.
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let _: S<'long, 'long> = c; //~ ERROR mismatched types
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}
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fn main() {}
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