mirror of https://github.com/rust-lang/rust
36 lines
935 B
Rust
36 lines
935 B
Rust
//@ check-pass
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//! The fields of a struct should be laid out in lexical order.
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#![crate_type = "lib"]
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#![feature(transmutability)]
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#![allow(dead_code)]
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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, {
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Assume::ALIGNMENT
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.and(Assume::LIFETIMES)
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.and(Assume::SAFETY)
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.and(Assume::VALIDITY)
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}>
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{}
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}
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#[repr(u8)] enum V0 { V = 0 }
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#[repr(u8)] enum V1 { V = 1 }
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#[repr(u8)] enum V2 { V = 2 }
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#[repr(C)] struct S01(V0, V1);
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#[repr(C)] struct S012(V0, V1, V2);
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fn should_order_tag_and_fields_correctly() {
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// An implementation that (incorrectly) arranges S01 as [0x01, 0x00] will,
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// in principle, reject this transmutation.
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assert::is_transmutable::<S01, V0>();
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// Again, but with one more field.
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assert::is_transmutable::<S012, S01>();
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}
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