rust/src/librustc_error_codes/error_codes/E0214.md

A generic type was described using parentheses rather than angle brackets. For example:

fn main() {
    let v: Vec(&str) = vec!["foo"];
}

This is not currently supported: v should be defined as Vec<&str>. Parentheses are currently only used with generic types when defining parameters for Fn-family traits.