diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs index 2d027f16e5d..fdeb276a58e 100644 --- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs +++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs @@ -45,7 +45,6 @@ where goal, goal.predicate.alias, ); - this.add_goal(GoalSource::AliasWellFormed, goal.with(cx, trait_ref)); this.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) }) diff --git a/tests/ui/coroutine/higher-ranked-rigid.rs b/tests/ui/coroutine/higher-ranked-rigid.rs new file mode 100644 index 00000000000..23a7d51300c --- /dev/null +++ b/tests/ui/coroutine/higher-ranked-rigid.rs @@ -0,0 +1,41 @@ +//@ edition: 2024 +//@ revisions: current next +//@ ignore-compare-mode-next-solver (explicit revisions) +//@[next] compile-flags: -Znext-solver +//@ check-pass + +// Regression test for . +// Coroutines erase all free lifetimes from their interior types, replacing them with higher- +// ranked regions which act as universals, to properly represent the fact that we don't know what +// the value of the region is within the coroutine. +// +// In the future in `from_request`, that means that the `'r` lifetime is being replaced in +// `>::Assoc`, which is in present in the existential bounds of the +// `dyn Future` that it's awaiting. Normalizing this associated type, with its free lifetimes +// replaced, means proving `T: FromRequest<'!0>`, which doesn't hold without constraining the +// `'!0` lifetime, which we don't do today. + +// Proving `T: Trait` holds when `::Assoc` is rigid is not necessary for soundness, +// at least not *yet*, and it's not even necessary for diagnostics since we have other special +// casing for, e.g., AliasRelate goals failing in the BestObligation folder. + +// The old solver unintentioanlly avoids this by never checking that `T: Trait` holds when +// `::Assoc` is rigid. Introducing this additional requirement when projecting rigidly +// in the old solver causes this (and tons of production crates) to fail. See the fallout from the +// crater run at . + +use std::future::Future; +use std::pin::Pin; + +pub trait FromRequest<'r> { + type Assoc; + fn from_request() -> Pin + Send>>; +} + +fn test<'r, T: FromRequest<'r>>() -> Pin + Send>> { + Box::pin(async move { + T::from_request().await; + }) +} + +fn main() {}