Function GetPounceComplementarityText 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn GetPounceComplementarityText(
    ipopt_problem: IpoptProblem,
    which: c_int,
    buf: *mut c_char,
    buflen: Index,
) -> Index

One of the driver’s free-form texts for the most recent driver solve, with C’s snprintf contract: writes at most buflen - 1 bytes of it plus a NUL into buf and returns its full length in bytes, without the NUL — so buf = NULL, buflen = 0 sizes the buffer, and a return >= buflen means it was truncated. Returns -1, writing nothing, when there is no such text: a NULL handle, a which that names none, whenever GetPounceComplementarityStats would return FALSE, or a text this run does not have (POUNCE_CC_TEXT_POLISH_REASON unless the polish ran and was not taken; POUNCE_CC_TEXT_B_REASON unless the B-stationarity check ran and was not decided). A NULL buf or a buflen <= 0 writes nothing and still returns the length.

Safety

ipopt_problem must be a valid IpoptProblem or NULL. buf, when non-NULL and buflen > 0, must have room for buflen bytes.