mirror of https://github.com/rust-lang/rust
26 lines
952 B
Rust
26 lines
952 B
Rust
// Test for specific details of how we handle higher-ranked subtyping to make
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// sure that any changes are made deliberately.
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//
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// - `let y = x` creates a `Subtype` obligation that is deferred for later.
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// - `w = a` sets the type of `x` to `Option<for<'a> fn(&'a ())>` and generalizes
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// `z` first to `Option<_>` and then to `Option<fn(&'0 ())>`.
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// - The various subtyping obligations are then processed.
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//
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// This requires that
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// 1. the `Subtype` obligation from `y = x` isn't processed while the types of
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// `w` and `a` are being unified.
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// 2. the pending subtype obligation isn't considered when determining the type
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// to generalize `z` to first (when related to the type of `y`).
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//
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// Found when considering fixes to #117151
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//@ check-pass
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fn main() {
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let mut x = None;
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let y = x;
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let z = Default::default();
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let mut w = (&mut x, z, z);
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let a = (&mut None::<fn(&())>, y, None::<fn(&'static ())>);
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w = a;
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}
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