constdefault 1.0.1

A const Default trait
Documentation 
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use constdefault::ConstDefault;
#[cfg(feature = "enable-atomics")]
use core::sync::atomic::{
    AtomicBool,
    AtomicI16,
    AtomicI32,
    AtomicI64,
    AtomicI8,
    AtomicIsize,
    AtomicPtr,
    AtomicU16,
    AtomicU32,
    AtomicU64,
    AtomicU8,
    AtomicUsize,
    Ordering,
};
use core::{
    cell::{Cell, RefCell},
    fmt::Debug,
};

/// Checks if both `ConstDefault` and `Default` implementations yield the same outcome.
fn compare_default_impls<T>()
where
    T: ConstDefault + Default + PartialEq + Debug,
{
    assert_eq!(<T as ConstDefault>::DEFAULT, <T as Default>::default());
}

macro_rules! compare_default_impls_for {
    ( $( $ty:ty ),* $(,)? ) => {{
        $(
            compare_default_impls::<$ty>();
        )*
    }};
}

#[test]
fn primitive_impls_work() {
    #[rustfmt::skip]
    compare_default_impls_for!(
        bool, char,
        i8, i16, i32, i64, i128, isize,
        u8, u16, u32, u64, u128, usize,
    );
}

#[test]
fn tuple_impls_work() {
    #[rustfmt::skip]
    compare_default_impls_for!(
        (),
        (i8,),
        (i8, i16),
        (i8, i16, i32),
        (i8, i16, i32, i64),
        (i8, i16, i32, i64, i128),
        (i8, i16, i32, i64, i128, isize),
        (i8, i16, i32, i64, i128, isize, u8),
        (i8, i16, i32, i64, i128, isize, u8, u16),
        (i8, i16, i32, i64, i128, isize, u8, u16, u32),
        (i8, i16, i32, i64, i128, isize, u8, u16, u32, u64),
        (i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128),
        (i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize),
    );
}

macro_rules! compare_default_impls_for_arrays {
    ( $( $n:literal ),* $(,)? ) => {{
        $(
            compare_default_impls::<[(); $n]>();
        )*
    }};
}

#[test]
fn array_impls_work() {
    #[rustfmt::skip]
    compare_default_impls_for_arrays!(
        0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
        10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
        20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
        30, 31, 32,
    );
}

#[cfg(feature = "enable-atomics")]
macro_rules! compare_default_impls_for_atomics {
    ( $( $atomic_type:ty ),* $(,)? ) => {{
        $(
            assert_eq!(
                <$atomic_type as ConstDefault>::DEFAULT.load(Ordering::SeqCst),
                <$atomic_type as Default>::default().load(Ordering::SeqCst),
            );
        )*
    }};
}

#[test]
#[cfg(feature = "enable-atomics")]
fn atomic_impls_work() {
    compare_default_impls_for_atomics!(
        AtomicBool,
        AtomicI16,
        AtomicI32,
        AtomicI64,
        AtomicI8,
        AtomicIsize,
        AtomicU16,
        AtomicU32,
        AtomicU64,
        AtomicU8,
        AtomicUsize,
    );
    assert_eq!(
        <AtomicPtr<()> as ConstDefault>::DEFAULT.load(Ordering::SeqCst),
        <AtomicPtr<()> as Default>::default().load(Ordering::SeqCst),
    );
}

macro_rules! compare_default_impls_for_cells {
    ( $( $cell_type:ty ),* $(,)? ) => {{
        $(
            assert_eq!(
                <$cell_type as ConstDefault>::DEFAULT.into_inner(),
                <$cell_type as Default>::default().into_inner(),
            );
        )*
    }};
}

#[test]
fn cell_impls_work() {
    #[rustfmt::skip]
    compare_default_impls_for_cells!(
        Cell<u8>,
        Cell<(u8, u16, u32)>,
        Cell<Cell<u8>>,
        RefCell<u8>,
        RefCell<(u8, u16, u32)>,
        RefCell<RefCell<u8>>,
    );
}