FcPatternAddWeak − Add a value to a pattern with weak binding
#include <fontconfig/fontconfig.h>
FcBool FcPatternAddWeak (FcPattern *p, const char *object, FcValue value, FcBool append);
FcPatternAddWeak is essentially the same as FcPatternAdd except that any values added to the list have binding weak instead of strong.
Fontconfig version 2.10.95