mirror of https://github.com/rust-lang/rust
25 lines
664 B
Rust
25 lines
664 B
Rust
#![feature(core_intrinsics)]
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#![feature(custom_mir)]
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// These cases are statically rejected by `mem::transmute`, so we need custom
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// MIR to be able to get to constant evaluation.
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use std::intrinsics::mir::*;
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#[custom_mir(dialect = "runtime", phase = "initial")]
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const unsafe fn mir_transmute<T, U>(x: T) -> U {
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mir!{
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{
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RET = CastTransmute(x);
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//~^ ERROR evaluation of constant value failed
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//~| ERROR evaluation of constant value failed
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Return()
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}
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}
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}
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const FROM_BIGGER: u16 = unsafe { mir_transmute(123_i32) };
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const FROM_SMALLER: u32 = unsafe { mir_transmute(123_i16) };
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fn main() {}
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