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Can't implement Drop on type with const_evaluatable_checked where bound #79248
Description
This issue seems to be specific to the Drop trait.
#![feature(const_generics)]
#![feature(const_evaluatable_checked)]
#![allow(incomplete_features)]
struct Bar<const N: usize>
where [(); N - 1]:
{
x: [u8; N - 1]
}
impl<const N: usize> Drop for Bar<N>
where [(); N - 1]:
{
fn drop(&mut self) {
}
}error[E0367]: `Drop` impl requires `[(); _]: '<empty>` but the struct it is implemented for does not
--> src/lib.rs:12:11
|
12 | where [(); N - 1]:
| ^^^^^^^^^^^
|
note: the implementor must specify the same requirement
--> src/lib.rs:5:1
|
5 | / struct Bar<const N: usize>
6 | | where [(); N - 1]:
7 | | {
8 | | x: [u8; N - 1]
9 | | }
| |_^
error[E0367]: `Drop` impl requires `the constant `<Bar<N> as Drop>::{constant#0}` can be evaluated` but the struct it is implemented for does not
--> src/lib.rs:12:16
|
12 | where [(); N - 1]:
| ^^^^^
|
note: the implementor must specify the same requirement
--> src/lib.rs:5:1
|
5 | / struct Bar<const N: usize>
6 | | where [(); N - 1]:
7 | | {
8 | | x: [u8; N - 1]
9 | | }
| |_^
rustc --version --verbose:
rustc 1.50.0-nightly (fe982319a 2020-11-19)
binary: rustc
commit-hash: fe982319aa0aa5bbfc2795791a753832292bd2ba
commit-date: 2020-11-19
host: x86_64-unknown-linux-gnu
release: 1.50.0-nightly
@rustbot label A-const-generics F-const_evaluatable_checked T-compiler
Reacted by jgarvin and TennyZhuang
Activity
tgnottingham commentedon Nov 20, 2020
Also, is it expected that the where bounds need to be repeated in each of the type's trait impls?
memoryruins commentedon Nov 29, 2020
Yes, bounds on type definitions need to be repeated in impls, at least until implied bounds are introduced.
3541 commentedon Jul 6, 2021
Is anyone aware of a way to work around this issue at the moment?