warning: the feature `generic_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/issue-68645-codegen-fulfillment.rs:3:12
   |
LL | #![feature(generic_associated_types)]
   |            ^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(incomplete_features)]` on by default
   = note: see issue #44265 <https://github.com/rust-lang/rust/issues/44265> for more information

error[E0277]: expected a `Fn<()>` closure, found `T`
  --> $DIR/issue-68645-codegen-fulfillment.rs:15:5
   |
LL |     type F<'a>: Fn() -> u32;
   |                 ----------- required by this bound in `Fun::F`
...
LL |     type F<'a> = Self;
   |     ^^^^^^^^^^^^^^^^^^ expected an `Fn<()>` closure, found `T`
   |
   = note: wrap the `T` in a closure with no arguments: `|| { /* code */ }`
help: consider restricting type parameter `T`
   |
LL | impl<T: Fn<()>> Fun for T {
   |       ^^^^^^^^

error: aborting due to previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0277`.