error[E0407]: method `unimplemented` is not a member of trait `std::ops::Add`
  --> $DIR/post-analysis-user-facing-param-env.rs:12:5
   |
LL | /     fn unimplemented(self, _: &Foo) -> Self::Output {
LL | |
LL | |         loop {}
LL | |     }
   | |_____^ not a member of trait `std::ops::Add`

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/post-analysis-user-facing-param-env.rs:2:12
   |
LL | #![feature(generic_const_exprs)]
   |            ^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
   = note: `#[warn(incomplete_features)]` on by default

error[E0046]: not all trait items implemented, missing: `Output`, `add`
  --> $DIR/post-analysis-user-facing-param-env.rs:6:1
   |
LL | / impl<'a, const NUM: usize> std::ops::Add<&'a Foo> for Foo
LL | |
LL | |
LL | | where
LL | |     [(); 1 + 0]: Sized,
   | |_______________________^ missing `Output`, `add` in implementation
   |
   = help: implement the missing item: `type Output = /* Type */;`
   = help: implement the missing item: `fn add(self, _: &'a Foo) -> <Self as Add<&'a Foo>>::Output { todo!() }`

error[E0207]: the const parameter `NUM` is not constrained by the impl trait, self type, or predicates
  --> $DIR/post-analysis-user-facing-param-env.rs:6:10
   |
LL | impl<'a, const NUM: usize> std::ops::Add<&'a Foo> for Foo
   |          ^^^^^^^^^^^^^^^^ unconstrained const parameter
   |
   = note: expressions using a const parameter must map each value to a distinct output value
   = note: proving the result of expressions other than the parameter are unique is not supported

error: aborting due to 3 previous errors; 1 warning emitted

Some errors have detailed explanations: E0046, E0207, E0407.
For more information about an error, try `rustc --explain E0046`.