FP `invalid left-hand side of assignment` function and enclosed var in closure same name

[matthiaskrgr]

this only repros when the fn and the var which is then used in the closure have the same name

fn i() {
    let mut i = 0;
    (|| i += 1 )();
}
fn main() {}

^ this compiled but not for ra diagnostics:

at crate ra, file /tmp/ra/src/main.rs: Error RustcHardError("E0067") from LineCol { line: 2, col: 8 } to LineCol { line: 2, col: 9 }: invalid left-hand side of assignment

[matthiaskrgr]

probably the same case

fn f() {
    let mut f = 1;
    f += 1;
}