``` rust mod Foo { fn x() {} } struct Foo; impl Foo { fn y() {} } fn main() {} ``` ``` <anon>:5:1: 5:23 error: duplicate definition of module `Foo` <anon>:5 impl Foo { fn y() {} } ^~~~~~~~~~~~~~~~~~~~~~ <anon>:3:1: 3:12 note: first definition of module `Foo` here <anon>:3 struct Foo; ^~~~~~~~~~~ error: aborting due to previous error ``` The "first definition" error should be pointing to the `mod Foo`.