mirror of https://github.com/rust-lang/rust
40 lines
1.0 KiB
Rust
40 lines
1.0 KiB
Rust
#![deny(unused_must_use)]
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#[must_use]
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trait Critical {}
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trait NotSoCritical {}
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trait DecidedlyUnimportant {}
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struct Anon;
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impl Critical for Anon {}
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impl NotSoCritical for Anon {}
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impl DecidedlyUnimportant for Anon {}
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fn get_critical() -> impl NotSoCritical + Critical + DecidedlyUnimportant {
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Anon {}
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}
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fn get_boxed_critical() -> Box<dyn Critical> {
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Box::new(Anon {})
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}
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fn get_nested_boxed_critical() -> Box<Box<dyn Critical>> {
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Box::new(Box::new(Anon {}))
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}
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fn get_critical_tuple() -> (u32, Box<dyn Critical>, impl Critical, ()) {
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(0, get_boxed_critical(), get_critical(), ())
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}
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fn main() {
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get_critical(); //~ ERROR unused implementer of `Critical` that must be used
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get_boxed_critical(); //~ ERROR unused boxed `Critical` trait object that must be used
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get_nested_boxed_critical();
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//~^ ERROR unused boxed boxed `Critical` trait object that must be used
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get_critical_tuple(); //~ ERROR unused boxed `Critical` trait object in tuple element 1
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//~^ ERROR unused implementer of `Critical` in tuple element 2
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}
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