error[E0053]: method `foo` has an incompatible type for trait
  --> $DIR/impl-generic-mismatch-ab.rs:8:32
   |
LL |     fn foo<A: Debug>(&self, a: &A, b: &impl Debug);
   |                                -- type in trait
...
LL |     fn foo<B: Debug>(&self, a: &impl Debug, b: &B) { }
   |            -                   ^^^^^^^^^^^ expected type parameter `B`, found type parameter `impl Debug`
   |            |
   |            expected type parameter
   |
   = note: expected fn pointer `fn(&(), &B, &impl Debug)`
              found fn pointer `fn(&(), &impl Debug, &B)`
   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters

error: aborting due to previous error

For more information about this error, try `rustc --explain E0053`.