Stream: t-compiler/wg-prioritization/alerts

Topic: I-prioritize #74018 ICE when playing around with existential


triagebot (Jul 03 2020 at 22:13, on Zulip):

@WG-prioritization/alerts issue #74018 has been requested for prioritization.

Procedure

LeSeulArtichaut (Jul 03 2020 at 22:18, on Zulip):

The following (totally incorrect, nightly features dependent) code is rejected without an ICE on the mentioned beta version, but nightly handles this less gracefully.

I think that makes it a P-medium?

lcnr (Jul 04 2020 at 08:42, on Zulip):

I think this can be P-low, considering that the compiler first outputs

   Compiling playground v0.0.1 (/playground)
error[E0658]: trait aliases are experimental
 --> src/lib.rs:2:1
  |
2 | trait UsedAlias<'a, T> = Iterator<Item = &'a UsedTypeAlias<T>>;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #41517 <https://github.com/rust-lang/rust/issues/41517> for more information
  = help: add `#![feature(trait_alias)]` to the crate attributes to enable

error[E0658]: trait aliases are experimental
 --> src/lib.rs:4:1
  |
4 | trait OtherTraitAlias<T> = where for<'r> &'r Self: IntoIterator<Item = UsedTypeAlias<T>>;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #41517 <https://github.com/rust-lang/rust/issues/41517> for more information
  = help: add `#![feature(trait_alias)]` to the crate attributes to enable

error[E0658]: `impl Trait` in type aliases is unstable
  --> src/lib.rs:11:28
   |
11 |     type Associated = S<T, impl UsedAlias<'a, T>>; // Line also necessary for the ICE
   |                            ^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
lcnr (Jul 04 2020 at 08:44, on Zulip):

https://github.com/rust-lang/rust/issues/69239 is the same with #![feature(const_generics)] and is P-medium, so either is fine for me :shrug:

LeSeulArtichaut (Jul 06 2020 at 15:43, on Zulip):

I think this issue will need to be fixed for #![feature(type_alias_impl_trait)] to be stabilized, so I would rather see P-medium than P-low, what do you think?

triagebot (Jul 07 2020 at 15:13, on Zulip):

Issue #74018's prioritization request has been removed.

DPC (Jul 07 2020 at 15:14, on Zulip):

went with p-medium

Last update: Apr 10 2021 at 21:00UTC