error[E0412]: cannot find type `err` in this scope
  --> $DIR/extern-fn-arg-names.rs:2:29
   |
LL |     fn dstfn(src: i32, dst: err);
   |                             ^^^ not found in this scope

error[E0061]: this function takes 2 arguments but 1 argument was supplied
  --> $DIR/extern-fn-arg-names.rs:7:5
   |
LL |     dstfn(1);
   |     ^^^^^--- argument #2 is missing
   |
note: function defined here
  --> $DIR/extern-fn-arg-names.rs:2:8
   |
LL |     fn dstfn(src: i32, dst: err);
   |        ^^^^^
help: provide the argument
   |
LL |     dstfn(1, /* dst */);
   |          ~~~~~~~~~~~~~~

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0061, E0412.
For more information about an error, try `rustc --explain E0061`.