Function slice_write 

#[doc(hidden)]
pub fn slice_write(
    pos_mut: &mut u64,
    slice: &mut [u8],
    buf: &[u8],
) -> Result<usize>

🔬This is a nightly-only experimental API. (core_io_internals)

Non-resizing Write::write implementation for slices. Exported for Cursor<Box<[u8], A>>’s implementation of Write.