error: expected one of `.`, `;`, `?`, or an operator, found keyword `let`
  --> $DIR/missing-semicolon.rs:3:12
   |
LL |         $( let x = $e1 )*;
   |            ^^^ expected one of `.`, `;`, `?`, or an operator
...
LL | fn main() { m!(0, 0; 0, 0); }
   |             --------------- in this macro invocation
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error