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47 lines
1.3 KiB
Rust
47 lines
1.3 KiB
Rust
// Check that deriving certain builtin traits on certain packed structs cause
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// errors. To avoid potentially misaligned references, field copies must be
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// used, which involves adding `T: Copy` bounds.
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#[derive(Copy, Clone, Default, PartialEq, Eq)]
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#[repr(packed)]
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pub struct Foo<T>(T, T, T);
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// This one is fine because the fields all impl `Copy`.
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#[derive(Default, Hash)]
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#[repr(packed)]
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pub struct Bar(u32, u32, u32);
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// This one is fine because it's not packed.
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#[derive(Debug, Default)]
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struct Y(usize);
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// This one has an error because `Y` doesn't impl `Copy`.
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// Note: there is room for improvement in the error message.
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#[derive(Debug, Default)]
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#[repr(packed)]
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struct X(Y);
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//~^ ERROR cannot move out of `self` which is behind a shared reference
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// This is currently allowed, but will be phased out at some point. From
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// `zerovec` within icu4x-0.9.0.
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#[derive(Debug)]
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#[repr(packed)]
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struct FlexZeroSlice {
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width: u8,
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data: [u8],
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//~^ WARNING byte slice in a packed struct that derives a built-in trait
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//~^^ this was previously accepted
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}
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// Again, currently allowed, but will be phased out.
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#[derive(Debug)]
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#[repr(packed)]
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struct WithStr {
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width: u8,
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data: str,
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//~^ WARNING string slice in a packed struct that derives a built-in trait
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//~^^ this was previously accepted
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}
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fn main() {}
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