error[E0277]: expected a `Fn<()>` closure, found `T`
  --> $DIR/issue-68642-broken-llvm-ir.rs:14:5
   |
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: std::ops::Fn<()>> Fun for T {
   |       ^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

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