arduino-hal: provide renamed types matching fields

[LuigiPiucco]

A very simple improvement to fix #558 and fix #555.

The approach is a basic application of renaming with paste!, but I choose to generate slightly different code than suggested:

pub struct Pins {
    // Notice the lack of documentation here, I thought it became redundant...
    pub a0: PinA0<
        mode::Input<mode::Floating>,
    >,
    // ...
}

// ...since I moved it to the type aliases themselves.

/// `A0`
///
/// * ADC0 (ADC input channel 0)
/// * PCINT8 (pin change interrupt 8)
pub type A0 = atmega_hal::port::PC0;
// ...

// It seemed more consistent to use the pin name in uppercase for the
// raw type and "Pin<pin name in uppercase>" for the wrapped version.

/// Safely wrapped version of:
/// `A0`
///
/// * ADC0 (ADC input channel 0)
/// * PCINT8 (pin change interrupt 8)
pub type PinA0<MODE> = Pin<MODE, atmega_hal::port::PC0>

In rust-analyzer the type aliases are resolved to the underlying type, so in this implementation the documentation popups still show the MCU names. We could fix this by using a newtype with Deref, but that seems like overkill.

[Rahix]

Hey, thanks a lot for taking care of this.

In rust-analyzer the type aliases are resolved to the underlying type, so in this implementation the documentation popups still show the MCU names. We could fix this by using a newtype with Deref, but that seems like overkill.

Same issue with compiler error messages. Such is the life of using type aliases in Rust at the moment... The only thing we can do is making sure people find the aliased type names in the docs easily.

Newtype won't work when HAL functions expect a specific pin. Yes, you can fix that using even more layers of traits and generics, but that's way worse still.

[Rahix]

Thanks a lot!!