mirror of https://github.com/rust-lang/rust
31 lines
614 B
Rust
31 lines
614 B
Rust
use std::ops::Deref;
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struct DerefWithHelper<H, T> {
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pub helper: H,
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pub value: Option<T>
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}
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trait Helper<T> {
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fn helper_borrow(&self) -> &T;
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}
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impl<T> Helper<T> for Option<T> {
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fn helper_borrow(&self) -> &T {
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self.as_ref().unwrap()
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}
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}
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impl<T, H: Helper<T>> Deref for DerefWithHelper<H, T> {
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type Target = T;
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fn deref(&self) -> &T {
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self.helper.helper_borrow()
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}
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}
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// Test cross-crate autoderef + vtable.
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pub fn check<T: PartialEq>(x: T, y: T) -> bool {
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let d: DerefWithHelper<Option<T>, T> = DerefWithHelper { helper: Some(x), value: None };
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d.eq(&y)
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}
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