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Rollup merge of rust-lang#120707 - compiler-errors:suitable-region, r…
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…=nnethercote

Don't expect early-bound region to be local when reporting errors in RPITIT well-formedness

The implicit lifetime in the example code gets replaced with `ReError`, which fails a `sub_regions` check in the lexical region solver. Error reporting ends up calling `is_suitable_region` on an early bound region in the *trait* definition. This causes an ICE because we `expect_local()`.

This is kind of a bad explanation, but this code just makes diagnostics reporting a bit more gracefully fallible. If the reviewer wants a thorough investigation of exactly where we get this region outlives obligation, I can write one up. Doesn't really seem worth it, though, imo.

Fixes rust-lang#120638
Fixes rust-lang#120648
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matthiaskrgr authored Feb 6, 2024
2 parents 012ce8a + d9cd0d4 commit 84114fe
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2 changes: 1 addition & 1 deletion compiler/rustc_middle/src/ty/context.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1193,7 +1193,7 @@ impl<'tcx> TyCtxt<'tcx> {
let (suitable_region_binding_scope, bound_region) = loop {
let def_id = match region.kind() {
ty::ReLateParam(fr) => fr.bound_region.get_id()?.as_local()?,
ty::ReEarlyParam(ebr) => ebr.def_id.expect_local(),
ty::ReEarlyParam(ebr) => ebr.def_id.as_local()?,
_ => return None, // not a free region
};
let scope = self.local_parent(def_id);
Expand Down
7 changes: 7 additions & 0 deletions tests/ui/async-await/in-trait/auxiliary/bad-region.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
// edition:2021

#[allow(async_fn_in_trait)]

pub trait BleRadio<'a> {
async fn transmit(&mut self);
}
17 changes: 17 additions & 0 deletions tests/ui/async-await/in-trait/bad-region.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
// aux-build:bad-region.rs
// edition:2021

#![allow(async_fn_in_trait)]

extern crate bad_region as jewel;

use jewel::BleRadio;

pub struct Radio {}

impl BleRadio for Radio {
//~^ ERROR implicit elided lifetime not allowed here
async fn transmit(&mut self) {}
}

fn main() {}
14 changes: 14 additions & 0 deletions tests/ui/async-await/in-trait/bad-region.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
error[E0726]: implicit elided lifetime not allowed here
--> $DIR/bad-region.rs:12:6
|
LL | impl BleRadio for Radio {
| ^^^^^^^^ expected lifetime parameter
|
help: indicate the anonymous lifetime
|
LL | impl BleRadio<'_> for Radio {
| ++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0726`.

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