mirror of https://github.com/rust-lang/rust
36 lines
954 B
Rust
36 lines
954 B
Rust
//@ check-pass
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//! The payloads of an enum variant should be ordered after its tag.
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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(u8)] enum E01 { V0(V1) = 0u8 }
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#[repr(u8)] enum E012 { V0(V1, V2) = 0u8 }
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fn should_order_tag_and_fields_correctly() {
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// An implementation that (incorrectly) arranges E01 as [0x01, 0x00] will,
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// in principle, reject this transmutation.
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assert::is_transmutable::<E01, V0>();
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// Again, but with one more field.
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assert::is_transmutable::<E012, E01>();
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}
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