include only checker error

Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

vlib/v/gen/c/testdata/check_combination_of_alias_and_sumtype.c.must_have

@@ -0,0 +1 @@
+// THE END.

vlib/v/gen/c/testdata/check_combination_of_alias_and_sumtype.v

@@ -0,0 +1,32 @@
+type ParseRes = Result<[]Token, ParseErr>
+
+struct ParseErr {}
+
+type Opt<T> = None<T> | Some<T>
+
+struct None<T> {}
+
+struct Some<T> {
+	value T
+}
+
+type Result<T, U> = Err<U> | Ok<T>
+
+struct Ok<T> {
+	value T
+}
+
+struct Err<U> {
+	value U
+}
+
+fn test_report() {
+	r := Opt<ParseRes>(None<ParseRes>{})
+	match r {
+		Some<ParseRes> {
+			// make possible cast fo the same type!
+			rx := Result<[]Token, ParseErr>(r.value)
+		}
+		None<ParseRes> {}
+	}
+}

vlib/v/tests/cmp_between_alias_and_sum_type_test.v

@@ -1,10 +0,0 @@
-struct Empty {}
-
-type IndexNumber = u32
-type NameIndexType = Empty | IndexNumber
-
-fn test_casting_with_sumtype_and_alias() {
-	elem := NameIndexType(Empty{})
-	if elem is IndexNumber {
-	}
-}