Sometimes macros need parentheses to call a method on their output, and sometimes not

[japaric]

STR

use std::io::MemWriter;

fn main() {
    let ref mut sink = MemWriter::new();
    match Some(true) {
        Some(_) => writeln!(sink, "Doesn't need parentheses").unwrap(),
        None => {},
    }
    writeln!(sink, "Needs parentheses!").unwrap();  //~ ERROR: unexpected token `.`
}

Version

rustc 0.12.0-pre (a356e9880 2014-09-06 10:31:29 +0000)

This feels inconsistent to me, I think we should stick to either making the parenthesis mandatory, or making the parentheses totally optional. In other words, in the above example, either both writeln! expressions should be rejected, or both should be accepted.

[bluss]

dup of #5941