diff options
Diffstat (limited to 'tests/ui/derives/deriving-with-repr-packed.rs')
-rw-r--r-- | tests/ui/derives/deriving-with-repr-packed.rs | 53 |
1 files changed, 27 insertions, 26 deletions
diff --git a/tests/ui/derives/deriving-with-repr-packed.rs b/tests/ui/derives/deriving-with-repr-packed.rs index 3884e3977..58be45197 100644 --- a/tests/ui/derives/deriving-with-repr-packed.rs +++ b/tests/ui/derives/deriving-with-repr-packed.rs @@ -1,45 +1,46 @@ -#![deny(unaligned_references)] - // Check that deriving certain builtin traits on certain packed structs cause -// errors. This happens when the derived trait would need to use a potentially -// misaligned reference. But there are two cases that are allowed: -// - If all the fields within the struct meet the required alignment: 1 for -// `repr(packed)`, or `N` for `repr(packed(N))`. -// - If `Default` is the only trait derived, because it doesn't involve any -// references. +// errors. To avoid potentially misaligned references, field copies must be +// used, which involves adding `T: Copy` bounds. #[derive(Copy, Clone, Default, PartialEq, Eq)] -//~^ ERROR `Clone` can't be derived on this `#[repr(packed)]` struct with type or const parameters -//~| hard error -//~^^^ ERROR `PartialEq` can't be derived on this `#[repr(packed)]` struct with type or const parameters -//~| hard error #[repr(packed)] pub struct Foo<T>(T, T, T); +// This one is fine because the fields all impl `Copy`. #[derive(Default, Hash)] -//~^ ERROR `Hash` can't be derived on this `#[repr(packed)]` struct that does not derive `Copy` -//~| hard error #[repr(packed)] pub struct Bar(u32, u32, u32); -// This one is fine because the field alignment is 1. -#[derive(Default, Hash)] -#[repr(packed)] -pub struct Bar2(u8, i8, bool); - -// This one is fine because the field alignment is 2, matching `packed(2)`. -#[derive(Default, Hash)] -#[repr(packed(2))] -pub struct Bar3(u16, i16, bool); - // This one is fine because it's not packed. #[derive(Debug, Default)] struct Y(usize); +// This one has an error because `Y` doesn't impl `Copy`. +// Note: there is room for improvement in the error message. #[derive(Debug, Default)] -//~^ ERROR `Debug` can't be derived on this `#[repr(packed)]` struct that does not derive `Copy` -//~| hard error #[repr(packed)] struct X(Y); +//~^ ERROR cannot move out of `self` which is behind a shared reference + +// This is currently allowed, but will be phased out at some point. From +// `zerovec` within icu4x-0.9.0. +#[derive(Debug)] +#[repr(packed)] +struct FlexZeroSlice { + width: u8, + data: [u8], + //~^ WARNING byte slice in a packed struct that derives a built-in trait + //~^^ this was previously accepted +} + +// Again, currently allowed, but will be phased out. +#[derive(Debug)] +#[repr(packed)] +struct WithStr { + width: u8, + data: str, + //~^ WARNING string slice in a packed struct that derives a built-in trait + //~^^ this was previously accepted +} fn main() {} |