mirror of https://github.com/rust-lang/rust
27 lines
1.4 KiB
Rust
27 lines
1.4 KiB
Rust
//! Test the part of RFC 2514 that is about not applying `DerefMut` coercions
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//! of union fields.
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use std::mem::ManuallyDrop;
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union U1<T> { x:(), f: ManuallyDrop<(T,)> }
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union U2<T> { x:(), f: (ManuallyDrop<(T,)>,) }
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fn main() {
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let mut u : U1<Vec<i32>> = U1 { x: () };
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unsafe { (*u.f).0 = Vec::new() }; // explicit deref, this compiles
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unsafe { u.f.0 = Vec::new() }; //~ERROR not automatically applying `DerefMut` on `ManuallyDrop` union field
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unsafe { &mut (*u.f).0 }; // explicit deref, this compiles
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unsafe { &mut u.f.0 }; //~ERROR not automatically applying `DerefMut` on `ManuallyDrop` union field
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unsafe { (*u.f).0.push(0) }; // explicit deref, this compiles
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unsafe { u.f.0.push(0) }; //~ERROR not automatically applying `DerefMut` on `ManuallyDrop` union field
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let mut u : U2<Vec<i32>> = U2 { x: () };
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unsafe { (*u.f.0).0 = Vec::new() }; // explicit deref, this compiles
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unsafe { u.f.0.0 = Vec::new() }; //~ERROR not automatically applying `DerefMut` on `ManuallyDrop` union field
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unsafe { &mut (*u.f.0).0 }; // explicit deref, this compiles
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unsafe { &mut u.f.0.0 }; //~ERROR not automatically applying `DerefMut` on `ManuallyDrop` union field
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unsafe { (*u.f.0).0.push(0) }; // explicit deref, this compiles
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unsafe { u.f.0.0.push(0) }; //~ERROR not automatically applying `DerefMut` on `ManuallyDrop` union field
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}
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