mirror of https://github.com/rust-lang/rust
38 lines
969 B
Rust
38 lines
969 B
Rust
//! ALL valid bit patterns of the source must be valid bit patterns of the
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//! destination type, unless validity is assumed.
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#![crate_type = "lib"]
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#![feature(transmutability)]
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#![allow(dead_code, incomplete_features, non_camel_case_types)]
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mod assert {
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use std::mem::{Assume, BikeshedIntrinsicFrom};
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pub fn is_transmutable<Src, Dst>()
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where
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Dst: BikeshedIntrinsicFrom<Src, { Assume::SAFETY }>
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// validity is NOT assumed -----^^^^^^^^^^^^^^^^^^
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{}
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}
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#[derive(Clone, Copy)] #[repr(u8)] enum Ox00 { V = 0x00 }
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#[derive(Clone, Copy)] #[repr(u8)] enum Ox7F { V = 0x7F }
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#[derive(Clone, Copy)] #[repr(u8)] enum OxFF { V = 0xFF }
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fn test() {
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#[repr(C)]
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union A {
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a: Ox00,
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b: Ox7F,
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}
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#[repr(C)]
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union B {
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a: Ox7F,
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b: OxFF,
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}
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assert::is_transmutable::<A, B>(); //~ ERROR cannot be safely transmuted
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assert::is_transmutable::<B, A>(); //~ ERROR cannot be safely transmuted
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}
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