error: any use of this value will cause an error
  --> $DIR/issue-50814.rs:15:21
   |
LL |     const MAX: u8 = A::MAX + B::MAX;
   |     -------------   ^^^^^^^^^^^^^^^ attempt to compute `u8::MAX + u8::MAX`, which would overflow
   |
   = note: `#[deny(const_err)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>

error[E0080]: evaluation of `foo::<i32>` failed
  --> $DIR/issue-50814.rs:21:6
   |
LL |     &Sum::<U8,U8>::MAX
   |      ^^^^^^^^^^^^^^^^^ referenced constant has errors

note: the above error was encountered while instantiating `fn foo::<i32>`
  --> $DIR/issue-50814.rs:26:5
   |
LL |     foo(0);
   |     ^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0080`.
Future incompatibility report: Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/issue-50814.rs:15:21
   |
LL |     const MAX: u8 = A::MAX + B::MAX;
   |     -------------   ^^^^^^^^^^^^^^^ attempt to compute `u8::MAX + u8::MAX`, which would overflow
   |
   = note: `#[deny(const_err)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>