FcConfigSubstitute − Execute substitutions
#include <fontconfig/fontconfig.h>
FcBool FcConfigSubstitute (FcConfig *config, FcPattern *p, FcMatchKind kind);
Calls FcConfigSubstituteWithPat setting p_pat to NULL. Returns FcFalse if the substitution cannot be performed (due to allocation failure). Otherwise returns FcTrue. If config is NULL, the current configuration is used.