Function inv_extract_clean

tests/repro/repro_invariant_lib.h:30–37

INV(extract-clean): extraction returns non-NULL and does not set has_error on * valid input (a parser crash/abort would not return at all → subprocess-isolate * crash-prone inputs with rh_extract_crashes instead). */

 * valid input (a parser crash/abort would not return at all → subprocess-isolate
 * crash-prone inputs with rh_extract_crashes instead). */
static inline int inv_extract_clean(const char *src, CBMLanguage lang, const char *file) {
    CBMFileResult *r = inv_rx(src, lang, file);
    if (!r)
        return 0;
    int ok = !r->has_error;
    cbm_free_result(r);
    return ok;
}

/* Count definitions whose label is/ isn't in the valid label set. */
static inline int inv_label_valid(const char *label) {