error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
  --> $DIR/issue-118048.rs:7:6
   |
LL | foo!(_);
   |      ^ not allowed in type signatures

error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
  --> $DIR/issue-118048.rs:7:6
   |
LL | foo!(_);
   |      ^ not allowed in type signatures
   |
   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0121`.