error: Mandatory argument is not assigned.
  --> $DIR/error-call-missing-assign.rs:5:15
   |
5  | pub fn foo<T>(a: T,b: f64 = 13.0, c: T = a*a) -> (T,f64,T)
   |               ^
...
16 |   foo!(b=0.1);
   |   ------------ in this macro invocation