Writing (...) after a name means “run this”. Turf found a name that is a plain value, not a function.
An enum variant is already a complete value. It doesn’t take arguments:
Example
enum Color { Red, Green }mut c: Color = Color::Red(); // Red is a value, not a functionmut c: Color = Color::Red; // just the nameThe same goes for an error variant that carries no payload fields: write IOError::NotFound, not IOError::NotFound() – unless it takes a message, in which case you pass exactly one string: IOError::NotFound("a.txt").
If you meant to build a struct, that is a call to its constructor: Point::new(1, 2) or Point::default().
Run turf --explain E135 in a terminal to read this again.