Stream: t-compiler/wg-prioritization/alerts

Topic: I-prioritize #74713 ICE: escaping bound vars in predicate


triagebot (Jul 24 2020 at 13:15, on Zulip):

@WG-prioritization/alerts issue #74713 has been requested for prioritization.

Procedure

DPC (Jul 24 2020 at 13:15, on Zulip):

ICE on stable hence prioritised

lcnr (Jul 25 2020 at 10:10, on Zulip):

This is a slight variation of #56445 and will probably be fixed while working on min_const_generics.

We can probably either close this as a duplicate or also assign P-high as it is a slightly different example, even if the cause should be identical

LeSeulArtichaut (Jul 26 2020 at 21:24, on Zulip):

IIUC this only happens in a failing path? Or am I missing something?

LeSeulArtichaut (Jul 26 2020 at 21:25, on Zulip):

If this only happens in a failing path then we should probably assign P-medium or even P-low given how old this regression is

lcnr (Jul 26 2020 at 21:25, on Zulip):

it's complicated

lcnr (Jul 26 2020 at 21:26, on Zulip):

so we don't supply the parent generics to arrays in function definitions and where bounds at all, so in this case it can currently never work

lcnr (Jul 26 2020 at 21:28, on Zulip):
fn bug<'a>() {
    let _ = [(); {
        let _: &'a ();
        3
    }];
}

has the same ICE but should theoretically compile rn because we do allow the parent generics in repeat expressions and enum discriminants

lcnr (Jul 26 2020 at 21:28, on Zulip):

So that's plainly a bug with const generics rn

LeSeulArtichaut (Jul 26 2020 at 21:30, on Zulip):

has the same ICE but should theoretically compile rn because we do allow the parent generics in repeat expressions and enum discriminants

I'm assuming it should compile with #![feature(const_generics)]?

lcnr (Jul 26 2020 at 21:30, on Zulip):

yeah

lcnr (Jul 26 2020 at 21:31, on Zulip):

I think it should compile even without #![feature(const_generics)]

LeSeulArtichaut (Jul 26 2020 at 21:32, on Zulip):

Because it is used for an array?

lcnr (Jul 26 2020 at 21:32, on Zulip):

it's complicated

^

LeSeulArtichaut (Jul 26 2020 at 21:32, on Zulip):

lcnr said:

it's complicated

^

I'm not ready for const generics yet then x)

LeSeulArtichaut (Jul 26 2020 at 21:33, on Zulip):

What would you suggest? Do you think this should be P-high?

lcnr (Jul 26 2020 at 21:33, on Zulip):

the repeat length is a concrete value here, so that should be just be equal to [(); 3] on stable

lcnr (Jul 26 2020 at 21:34, on Zulip):

Hmm, so without considering how we might fix this, this is still an ICE which is fairly easy to hit so it should be P-high

triagebot (Jul 29 2020 at 15:13, on Zulip):

Issue #74713's prioritization request has been removed.

Last update: Apr 11 2021 at 18:30UTC