confusing error message from (object).method() with &mut self

[thestinger]

foo.rs:11:5: 11:6 error: moving out of mutable local variable prohibited due to outstanding loan
foo.rs:11     (a).bar();
               ^
foo.rs:11:5: 11:6 note: loan of mutable local variable granted here
foo.rs:11     (a).bar();
             ^
error: aborting due to previous error

The compiler seems to consider (a) as an evaluation to a temporary value of the same type, which results in a quite confusing error. This doesn't occur with function((&mut x)). @bstrie discovered this while removing mut fields.

[alexcrichton]

This may be somewhat related to #4666

[emberian]

Cannot reproduce; needs test.

[alexcrichton]

I think that this has been fixed in the past borrowck changes. The test case which now passes I believe was:

struct A;

impl A {
    fn foo(&mut self) {}
}

fn main() {
    let mut a = A;
    (a).foo();
}

If there's something else at play though, this should definitely be reopened!