50 lines
1.0 KiB
Rust
50 lines
1.0 KiB
Rust
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//@ check-fail
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//! Reject extensions behind references.
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#![crate_type = "lib"]
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#![feature(transmutability)]
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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<
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Src,
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{
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Assume {
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alignment: true,
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lifetimes: true,
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safety: true,
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validity: true,
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}
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},
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>,
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{
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}
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}
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#[repr(C, packed)]
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struct Packed<T>(T);
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fn reject_extension() {
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#[repr(C, align(2))]
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struct Two(u8);
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#[repr(C, align(4))]
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struct Four(u8);
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// These two types differ in the number of trailing padding bytes they have.
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type Src = Packed<Two>;
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type Dst = Packed<Four>;
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const _: () = {
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use std::mem::size_of;
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assert!(size_of::<Src>() == 2);
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assert!(size_of::<Dst>() == 4);
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};
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assert::is_transmutable::<&Src, &Dst>(); //~ ERROR cannot be safely transmuted
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}
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