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test: make <[T; N]>::default use const generics #146531

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test: make <[T; N]>::default use const generics #146531

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27 changes: 5 additions & 22 deletions library/core/src/array/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -469,30 +469,13 @@ impl<T: Copy> SpecArrayClone for T {
}
}

// The Default impls cannot be done with const generics because `[T; 0]` doesn't
// require Default to be implemented, and having different impl blocks for
// different numbers isn't supported yet.

macro_rules! array_impl_default {
{$n:expr, $t:ident $($ts:ident)*} => {
#[stable(since = "1.4.0", feature = "array_default")]
impl<T> Default for [T; $n] where T: Default {
fn default() -> [T; $n] {
[$t::default(), $($ts::default()),*]
}
}
array_impl_default!{($n - 1), $($ts)*}
};
{$n:expr,} => {
#[stable(since = "1.4.0", feature = "array_default")]
impl<T> Default for [T; $n] {
fn default() -> [T; $n] { [] }
}
};
#[stable(since = "1.4.0", feature = "array_default")]
impl<T: Default, const N: usize> Default for [T; N] {
fn default() -> Self {
from_fn(|_| T::default())
}
}

array_impl_default! {32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T}

impl<T, const N: usize> [T; N] {
/// Returns an array of the same size as `self`, with function `f` applied to each element
/// in order.
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