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|
#![feature(derive_coerce_pointee, arbitrary_self_types)]
extern crate core;
use std::marker::CoercePointee;
#[derive(CoercePointee)]
//~^ ERROR: `CoercePointee` can only be derived on `struct`s with `#[repr(transparent)]`
enum NotStruct<'a, T: ?Sized> {
Variant(&'a T),
}
#[derive(CoercePointee)]
//~^ ERROR: `CoercePointee` can only be derived on `struct`s with at least one field
#[repr(transparent)]
struct NoField<'a, #[pointee] T: ?Sized> {}
//~^ ERROR: lifetime parameter `'a` is never used
//~| ERROR: type parameter `T` is never used
#[derive(CoercePointee)]
//~^ ERROR: `CoercePointee` can only be derived on `struct`s with at least one field
#[repr(transparent)]
struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
//~^ ERROR: lifetime parameter `'a` is never used
//~| ERROR: type parameter `T` is never used
#[derive(CoercePointee)]
//~^ ERROR: `CoercePointee` can only be derived on `struct`s that are generic over at least one type
#[repr(transparent)]
struct NoGeneric<'a>(&'a u8);
#[derive(CoercePointee)]
//~^ ERROR: exactly one generic type parameter must be marked as `#[pointee]` to derive `CoercePointee` traits
#[repr(transparent)]
struct AmbiguousPointee<'a, T1: ?Sized, T2: ?Sized> {
a: (&'a T1, &'a T2),
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct TooManyPointees<'a, #[pointee] A: ?Sized, #[pointee] B: ?Sized>((&'a A, &'a B));
//~^ ERROR: only one type parameter can be marked as `#[pointee]` when deriving `CoercePointee` traits
#[derive(CoercePointee)]
//~^ ERROR: `CoercePointee` can only be derived on `struct`s with `#[repr(transparent)]`
struct NotTransparent<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct NoMaybeSized<'a, #[pointee] T> {
//~^ ERROR: `derive(CoercePointee)` requires `T` to be marked `?Sized`
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct PointeeOnField<'a, #[pointee] T: ?Sized> {
#[pointee]
//~^ ERROR: the `#[pointee]` attribute may only be used on generic parameters
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct PointeeInTypeConstBlock<
'a,
T: ?Sized = [u32; const {
struct UhOh<#[pointee] T>(T);
//~^ ERROR: the `#[pointee]` attribute may only be used on generic parameters
10
}],
> {
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct PointeeInConstConstBlock<
'a,
T: ?Sized,
const V: u32 = {
struct UhOh<#[pointee] T>(T);
//~^ ERROR: the `#[pointee]` attribute may only be used on generic parameters
10
},
> {
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct PointeeInAnotherTypeConstBlock<'a, #[pointee] T: ?Sized> {
ptr: PointeeInConstConstBlock<
'a,
T,
{
struct UhOh<#[pointee] T>(T);
//~^ ERROR: the `#[pointee]` attribute may only be used on generic parameters
0
},
>,
}
// However, reordering attributes should work nevertheless.
#[repr(transparent)]
#[derive(CoercePointee)]
struct ThisIsAPossibleCoercePointee<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}
// Also, these paths to Sized should work
#[derive(CoercePointee)]
#[repr(transparent)]
struct StdSized<'a, #[pointee] T: ?std::marker::Sized> {
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct CoreSized<'a, #[pointee] T: ?core::marker::Sized> {
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct GlobalStdSized<'a, #[pointee] T: ?::std::marker::Sized> {
ptr: &'a T,
}
#[derive(CoercePointee)]
#[repr(transparent)]
struct GlobalCoreSized<'a, #[pointee] T: ?::core::marker::Sized> {
ptr: &'a T,
}
fn main() {}
|
