This just removes the declarations. I'm not exactly sure on the process to fix the tests.

Do the tests still pass?

No. Multiple tests fail.

A simple example is run-pass/expr-copy. Without legacy_modes, the first call to f moves x and then the second call will fail with "error: use of moved value: x" The premise for the test no longer really holds true. Perhaps a faithful recreation could be:

fn f(arg: A) {
    arg.a = 100;
}

fn g(arg: &mut A) {
    arg.a = 100;
}

struct A { mut a: int }

pub fn main() {
    let mut x = A {a: 10};
    g(&mut x);
    assert x.a == 100;
    x.a = 20;
    f(copy x);
    assert x.a == 20;
}

So, fixing some of the tests require these kinds of semantic changes. I'll take a crack at trying to fix them, if you want, though.

@codeblack08 Please try to make the tests pass (ask on IRC or here if you need help) and re-submit after that. bors won't merge any commits that cause tests to fail anyway :-)

Closing this for now, please do start another pull request if you have a chance to fix the tests.