error: no rules expected `!`
  --> $DIR/macro-doc-comments-1.rs:6:5
   |
LL | macro_rules! outer {
   | ------------------ when calling this macro
...
LL |     //! Inner
   |     ^^^^^^^^^
   |     |
   |     no rules expected this token in macro call
   |     inner doc comments expand to `#![doc = "..."]`, which is what this macro attempted to match
   |
note: while trying to match `[`
  --> $DIR/macro-doc-comments-1.rs:2:7
   |
LL |     (#[$outer:meta]) => ()
   |       ^

error: aborting due to 1 previous error