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Passing a non-const trait function item value to a const fn is no longer allowed in a constant context #104155
Description
Code
I tried this code:
const _: () = core::mem::forget(Box::<u32>::default); // ERROR
const _: () = core::mem::forget(|| Box::<u32>::default()); // okI expected to see this happen: Successful compilation
Instead, this happened:
error[E0277]: the trait bound `Box<u32>: Default` is not satisfied
--> src/lib.rs:1:15
|
1 | const _: () = core::mem::forget(Box::<u32>::default);
| ^^^^^^^^^^^^^^^^^ the trait `~const Default` is not implemented for `Box<u32>`
|
note: the trait `Default` is implemented for `Box<u32>`, but that implementation is not `const`
--> src/lib.rs:1:15
|
1 | const _: () = core::mem::forget(Box::<u32>::default);
| ^^^^^^^^^^^^^^^^^
Version it worked on
It most recently worked on: 1.65.0
Version with regression
rustc --version --verbose:
rustc 1.66.0-beta.1 (e080cc5a6 2022-11-01)
binary: rustc
commit-hash: e080cc5a659fb760c0bc561b722a790dad35b5e1
commit-date: 2022-11-01
host: aarch64-apple-darwin
release: 1.66.0-beta.1
LLVM version: 15.0.2
@rustbot modify labels: +regression-from-stable-to-beta -regression-untriaged
Activity
jruderman commentedon Nov 8, 2022
This became an error due to #100982 (@fee1-dead, @oli-obk).
Bisect info
searched nightlies: from nightly-2022-09-18 to nightly-2022-11-07
regressed nightly: nightly-2022-09-23
searched commit range: 9062b78...e7119a0
regressed commit: 7a8636c
bisected with cargo-bisect-rustc v0.6.4
Host triple:
x86_64-apple-darwinI used
cargo bisect-rustc --regress erroron the following fileinquisitivecrystal commentedon Nov 9, 2022
Assigning priority as discussed by the Prioritization Working Group.
Auto merge of rust-lang#104180 - fee1-dead-contrib:fix-wf-fndef, r=ol…
fee1-dead commentedon Nov 9, 2022
awaiting beta backport
fix(bind): wrap `Default::default` in a closure when passing to `Bind…
Revert "fix(bind): wrap `Default::default` in a closure when passing …
yvt commentedon Nov 23, 2022
Can this be closed now that beta backport (#104447) is complete?