Feature gate: #![feature(const_default)]

This is a tracking issue for Default in const fn

Public API

// core::default
pub const trait Default: Sized {
    fn default() -> Self;
}

impl const Default types:

• ()
• bool
• char
• std::ascii::Char
• usize
• u8
• u16
• u32
• u64
• u128
• i8
• i16
• i32
• i64
• i128
• f16
• f32
• f64
• f128
• std::marker::PhantomData<T>
• Option<T>
• std::iter::Empty<T>
• std::ptr::Alignment
• &[T]
• &mut [T]
• &str
• &mut str
• String
• Vec<T>

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• Implementation: Make Default const and add some const Default impls #134628
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• Blocked on Tracking Issue for RFC 3762, "Make trait methods callable in const contexts" #143874