37 lines
1.0 KiB
Rust
37 lines
1.0 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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// Regression test for #31299. This was generating an overflow error
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// because of eager normalization:
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//
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// proving `M: Sized` requires
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// - proving `PtrBack<Vec<M>>: Sized` requis
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// - normalizing `Vec<<Vec<M> as Front>::Back>>: Sized` requires
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// - proving `Vec<M>: Front` requires
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// - `M: Sized` <-- cycle!
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//
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// If we skip the normalization step, though, everything goes fine.
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trait Front {
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type Back;
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}
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impl<T> Front for Vec<T> {
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type Back = Vec<T>;
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}
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struct PtrBack<T: Front>(Vec<T::Back>);
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struct M(PtrBack<Vec<M>>);
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fn main() {
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std::mem::size_of::<M>();
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}
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