Change:
<!-- Thank you for finding an Internal Compiler Error! If possible, try to provide a minimal verifiable example. You can read "Rust Bug Minimization Patterns" for how to create smaller examples. --<!-- If you're using the stable version of the compiler, you should also check if the bug also exists in the beta or nightly versions. --: <!-- Include a backtrace in the code block by setting in your environment. E.g. . --<details<summary<strongBacktrace</strong</summary<p</p</details<strongICE location label +F-unboxedclosures
Regression in nightly-2024-03-22
Minimized: <details<summaryError output</summary</details labels -F-unboxed_closures
duplicate of ?
it would be nice if you could check the bugtracker before posting something, as right now about 30-50% of your bugreports are just re-reports of ices we already know about it seems :upsidedownface:

Discussion:
{ if let Some(where_pred) = where_pred.as_trait_clause() && let Some(failed_pred) = failed_pred.as_trait_clause() <ins> && where_pred.def_id() == failed_pred.def_id() </ins> { self.enter_forall(where_pred, |where_pred| { let failed_pred = self.instantiate_binder_with_fresh_vars(

<del> //@ known-bug: rust-lang/rust#126416 trait Output<'a, T: 'a> { type Type; } struct Wrapper; impl Wrapper { fn do_something_wrapper<O, F>(&mut self, _: F) where F: for<'a> FnOnce(<F as Output<i32>>::Type), { } } fn main() { let mut wrapper = Wrapper; wrapper.do_something_wrapper(|value| ()); } </del>

<ins> trait Output<'a> { type Type; } struct Wrapper; impl Wrapper { fn do_something_wrapper<O, F>(self, _: F) //~^ ERROR the trait bound `for<'a> F: Output<'a>` is not satisfied //~| ERROR the trait bound `for<'a> F: Output<'a>` is not satisfied where F: for<'a> FnOnce(<F as Output<'a>>::Type), //~^ ERROR the trait bound `F: Output<'_>` is not satisfied //~| ERROR the trait bound `F: Output<'_>` is not satisfied { } } fn main() { let mut wrapper = Wrapper; wrapper.do_something_wrapper(|value| ()); //~^ ERROR expected a `FnOnce } </ins>

<ins> error[E0277]: the trait bound `for<'a> F: Output<'a>` is not satisfied --> $DIR/filter-relevant-fn-bounds.rs:8:5 | LL | /     fn do_something_wrapper<O, F>(self, _: F) LL | | LL | | LL | |     where LL | |         F: for<'a> FnOnce(<F as Output<'a>>::Type), | |___________________________________________________^ the trait `for<'a> Output<'a>` is not implemented for `F` | help: consider further restricting this bound | LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type) + for<'a> Output<'a>, |                                                    ++++++++++++++++++++ error[E0277]: the trait bound `for<'a> F: Output<'a>` is not satisfied --> $DIR/filter-relevant-fn-bounds.rs:8:8 | LL |     fn do_something_wrapper<O, F>(self, _: F) |        ^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> Output<'a>` is not implemented for `F` | help: consider further restricting this bound | LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type) + for<'a> Output<'a>, |                                                    ++++++++++++++++++++ error[E0277]: the trait bound `F: Output<'_>` is not satisfied --> $DIR/filter-relevant-fn-bounds.rs:12:12 | LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type), |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Output<'_>` is not implemented for `F` | help: consider further restricting this bound | LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type) + Output<'_>, |                                                    ++++++++++++ error[E0277]: the trait bound `F: Output<'_>` is not satisfied --> $DIR/filter-relevant-fn-bounds.rs:12:20 | LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type), |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Output<'_>` is not implemented for `F` | help: consider further restricting this bound | LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type) + Output<'_>, |                                                    ++++++++++++ error[E0277]: expected a `FnOnce(<{closure@$DIR/filter-relevant-fn-bounds.rs:21:34: 21:41} as Output<'a>>::Type)` closure, found `{closure@$DIR/filter-relevant-fn-bounds.rs:21:34: 21:41}` --> $DIR/filter-relevant-fn-bounds.rs:21:34 | LL |     wrapper.do_something_wrapper(|value| ()); |             -------------------- ^^^^^^^^^^ expected an `FnOnce(<{closure@$DIR/filter-relevant-fn-bounds.rs:21:34: 21:41} as Output<'a>>::Type)` closure, found `{closure@$DIR/filter-relevant-fn-bounds.rs:21:34: 21:41}` |             | |             required by a bound introduced by this call | = help: the trait `for<'a> Output<'a>` is not implemented for closure `{closure@$DIR/filter-relevant-fn-bounds.rs:21:34: 21:41}` help: this trait has no implementations, consider adding one --> $DIR/filter-relevant-fn-bounds.rs:1:1 | LL | trait Output<'a> { | ^^^^^^^^^^^^^^^^ note: required by a bound in `Wrapper::do_something_wrapper` --> $DIR/filter-relevant-fn-bounds.rs:12:12 | LL |     fn do_something_wrapper<O, F>(self, _: F) |        -------------------- required by a bound in this associated function ... LL |         F: for<'a> FnOnce(<F as Output<'a>>::Type), |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Wrapper::do_something_wrapper` error: aborting due to 5 previous errors For more information about this error, try `rustc --explain E0277`. </ins>