Function decoder_max_utf16_buffer_length 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn decoder_max_utf16_buffer_length(
    decoder: *const Decoder,
    u16_length: usize,
) -> usize

Query the worst-case UTF-16 output size (with or without replacement).

Returns the size of the output buffer in UTF-16 code units (char16_t) that will not overflow given the current state of the decoder and byte_length number of additional input bytes or SIZE_MAX if size_t would overflow.

Since the REPLACEMENT CHARACTER fits into one UTF-16 code unit, the return value of this method applies also in the _without_replacement case.

Undefined behavior

UB ensues if decoder is NULL.