repochecker: Ensure non-optional flag doesn't depend on optional one

admin/sync/exercice_keys.go

@@ -555,6 +555,15 @@ func CheckExerciceFlags(i Importer, exercice *fic.Exercice, files []string, exce
 				}
 			}
 
+			// Check dependency to flag optional flag
+			if fk, ok := flag.Flag.(*fic.FlagKey); ok && fk.BonusGain == 0 {
+				for _, nf := range flag.FlagsDeps {
+					if fk2, ok := flags[nf].Flag.(*fic.FlagKey); ok && fk2.BonusGain != 0 {
+						errs = multierr.Append(errs, NewFlagError(exercice, nil, flag.Line, fmt.Errorf("flag is not optional but depend on flag id=%d which is optional", nf)))
+					}
+				}
+			}
+
 			// Check dependency loop
 			deps := flag.FlagsDeps
 			for i := 0; i < len(deps); i++ {