Repository navigation
incompletely relating alias args may cause borrowck ICE #140211
Description
trait Id {
type This<'a>;
}
#[derive(Copy, Clone)]
struct W<T>(T);
impl Id for W<u32> {
type This<'a> = W<u32>;
}
impl Id for W<i32> {
type This<'a> = W<i32>;
}
trait Trait<T> {}
// when using this impl we only normalize after instantiating
// with infer vars, at this point `<?t as Id>::This<'a>` is still
// ambig, so we keep the alias around and require it to structurally
// relate.
impl<T: Id> Trait<for<'a> fn(T::This<'a>)> for T {}
fn is_trait<T: Trait<U>, U>(_x: T) {}
fn main() {
let x = W(1);
// We prove `W<_>: Trait<for<'a> fn(<W<_>>::This<'a>)>` during
// typeck, and `W<i32>: Trait<for<'a> fn(<W<i32>)>` during borrowck.
// This then fails.
is_trait(x);
let _: W<i32> = x;
}ICEs with
error: internal compiler error: error performing operation: fully_perform
--> src/main.rs:20:5
|
20 | is_trait::<_, _>(x);
| ^^^^^^^^^^^^^^^^^^^
|
note: delayed at /rustc/05f9846f893b09a1be1fc8560e33fc3c815cfecb/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs:87:25 - disabled backtrace
--> src/main.rs:20:5
|
20 | is_trait::<_, _>(x);
| ^^^^^^^^^^^^^^^^^^^
Activity
[-]imcompletely relating alias args may cause borrowck ICE[/-][+]incompletely relating alias args may cause borrowck ICE[/+]Rollup merge of rust-lang#163796 - lcnr:crashes-migration, r=lqd
Rollup merge of rust-lang#163796 - lcnr:crashes-migration, r=lqd
Unrolled build for #163796 in rollup 163829
failed to resolve instance for <fn(FooImpl, ()) as FooFn>::bar#139120 as a duplicate of this issueRollup merge of rust-lang#163806 - lcnr:crashes-migration-cont, r=lqd
Rollup merge of rust-lang#163806 - lcnr:crashes-migration-cont, r=lqd
Rollup merge of rust-lang#163806 - lcnr:crashes-migration-cont, r=lqd
Unrolled build for #163806 in rollup 163957