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https://github.com/rust-lang/rust
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16 lines
339 B
Rust
16 lines
339 B
Rust
// run-pass
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#![allow(non_camel_case_types)]
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trait double {
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fn double(self: Box<Self>) -> usize;
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}
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impl double for Box<usize> {
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fn double(self: Box<Box<usize>>) -> usize { **self * 2 }
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}
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pub fn main() {
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let x: Box<Box<Box<Box<Box<_>>>>> = Box::new(Box::new(Box::new(Box::new(Box::new(3)))));
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assert_eq!(x.double(), 6);
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}
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