error: overly complex generic constant
  --> $DIR/issue-77357.rs:6:46
   |
LL | fn bug<'a, T>() -> &'static dyn MyTrait<[(); { |x: &'a u32| { x }; 4 }]> {
   |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^ blocks are not supported in generic constants
   |
   = help: consider moving this anonymous constant into a `const` function
   = note: this operation may be supported in the future

error: aborting due to previous error