Function `from_boxed_utf8_unchecked_in`

#[must_use]
pub(crate) unsafe fn from_boxed_utf8_unchecked_in<A: Allocator>(v: Box<[u8], A>) -> Box<str, A>

Internal; same as from_boxed_utf8_unchecked but allocator-generic. Name probably not suitable for being made pub as-is.