v2: implement sym types & handle in table.check

vlib/v/table/atype_symbols.v

@@ -8,7 +8,7 @@ import (
 )
 
 pub type TypeInfo = Array | ArrayFixed | Map | Struct | 	
-MultiReturn | Alias | Enum
+MultiReturn | Alias | Enum | SumType
 
 pub struct TypeSymbol {
 pub:
@@ -399,6 +399,10 @@ pub mut:
 	value_type Type
 }
 
+pub struct SumType {
+	variants []Type
+}
+
 pub fn (table &Table) type_to_str(t Type) string {
 	sym := table.get_type_symbol(t)
 	if sym.kind == .multi_return {

vlib/v/table/table.v

@@ -413,6 +413,19 @@ pub fn (t &Table) check(got, expected Type) bool {
 	if got_type_sym.kind == .array && got_type_sym.name == 'array_void' && exp_type_sym.kind == .array {
 		return true
 	}
+	// sum type
+	if got_type_sym.kind == .sum_type {
+		sum_info := got_type_sym.info as SumType
+		if expected in sum_info.variants {
+			return true
+		}
+	}
+	else if exp_type_sym.kind == .sum_type {
+		sum_info := exp_type_sym.info as SumType
+		if got in sum_info.variants {
+			return true
+		}
+	}
 	if got_idx != exp_idx {
 		// && got.typ.name != expected.typ.name*/
 		return false

vlib/v/table/types.v

@@ -8,6 +8,15 @@ pub enum TypeExtra {
 	variadic
 }
 
+pub fn (types []Type) contains(typ Type) bool {
+	for t in types {
+		if int(typ) == int(t) {
+			return true
+		}
+	}
+	return false
+}
+
 // return underlying TypeSymbol idx
 [inline]
 pub fn type_idx(t Type) int {