v2: implement sym types & handle in table.check

vlib/v/parser/parser.v

@@ -1837,11 +1837,13 @@ fn (p mut Parser) type_decl() ast.TypeDecl {
 	p.check(.key_type)
 	name := p.check_name()
 	mut is_sum := false
+	mut sum_variants := []table.Type
 	// type SumType = A | B | c
 	if p.tok.kind == .assign {
 		p.next()
 		for {
-			p.check_name()
+			variant_type := p.parse_type()
+			sum_variants << variant_type
 			if p.tok.kind != .pipe {
 				break
 			}
@@ -1852,13 +1854,23 @@ fn (p mut Parser) type_decl() ast.TypeDecl {
 	else {
 		p.parse_type()
 	}
-	p.table.register_type_symbol(table.TypeSymbol{
-		kind: .sum_type
-		name: name
-		info: table.Alias{
-			foo: ''
-		}
-	})
+	if is_sum {
+		p.table.register_type_symbol(table.TypeSymbol{
+			kind: .sum_type
+			name: p.prepend_mod(name)
+			info: table.SumType{
+				variants: sum_variants
+			}
+		})
+	} else {
+		p.table.register_type_symbol(table.TypeSymbol{
+			kind: .alias
+			name: p.prepend_mod(name)
+			info: table.Alias{
+				foo: ''
+			}
+		})
+	}
 	return ast.TypeDecl{
 		name: name
 	}

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 {