error[E0369]: binary operation `==` cannot be applied to type `for<'a> fn(&'a i32) -> &'a i32 {foo}`
  --> $DIR/issue-77910-2.rs:7:12
   |
LL |     if foo == y {}
   |        --- ^^ - _
   |        |
   |        for<'a> fn(&'a i32) -> &'a i32 {foo}
   |
help: use parentheses to call this function
   |
LL |     if foo(/* &i32 */) == y {}
   |           ++++++++++++

error[E0381]: used binding `xs` isn't initialized
  --> $DIR/issue-77910-2.rs:3:5
   |
LL |     let xs;
   |         -- binding declared here but left uninitialized
LL |     xs
   |     ^^ `xs` used here but it isn't initialized
   |
help: consider assigning a value
   |
LL |     let xs = &42;
   |            +++++

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0369, E0381.
For more information about an error, try `rustc --explain E0369`.