Fix some invalid msg_send! usage

[madsmtm]

Change a few types for more correct behaviour (e.g. using bool may be undefined behaviour, one should use BOOL).

The only critical thing here is the stuff in unmark_text (introduced in #2119), that part is certainly undefined behaviour, and will probably cause problems somewhere down the line.

• Tested on all platforms changed
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality
• Updated feature matrix, if new features were added or implemented

[ArturKovacs]

Thank you for making these improvements.

There is one thing that bugs me. The fact that we have to write

my_objc_bool != NO

I know that it's necessary to compare against NO, but then we have a double negation for every single truthy check.

Here's an alternative:

trait BoolYeah {
    /// This is true when `self` is not `NO`
    /// 
    /// Note that this different from
    /// `self == YES`
    /// because YES is the value 1 but
    /// a BOOL may be any signed 8bit value
    fn yeah(self) -> bool;
    fn no(self) -> bool;
}
impl BoolYeah for objc::runtime::BOOL {
    #[inline]
    fn yeah(self) -> bool {
        self != 0
    }
    #[inline]
    fn no(self) -> bool {
        self == 0
    }
}

So that we can write

if window_has_focus.yeah() {

[aloucks]

trait BoolYeah

It would be more clear to have is_true() and is_false() instead of yeah() and no().

[ArturKovacs]

Just to throw another option into the mix, what about truthy() and falsy()? This naming comes from JavaScript.

[maroider]

Maybe just a conversion, e.g. .to_bool(), would be good enough.
If not, then some variation of truthy and falsy sounds good to me.

[madsmtm]

In my fork of objc I've added a Bool newtype, which has as_bool (and is_true and is_false for those that want to use that) to make this exact thing better.

I intend to use that fork in winit at some point, but for this PR I wanted to keep the focus on correctness over niceness.

[ArturKovacs]

Alright, I'm looking forward to moving to your fork of objc then.

[madsmtm]

Alright, I'm looking forward to moving to your fork of objc then.

Thanks! Though intending to move to something else in the unknown future shouldn't be a blocker for adding BoolYeah now, just not something I'd want to do in this PR in any case.

[ArturKovacs]

Awesome!