all: add support for `type MyEnumAlias = MyEnum`

vlib/v/ast/table.v

@@ -678,6 +678,16 @@ pub fn (t &Table) unalias_num_type(typ Type) Type {
 	return typ
 }
 
+[inline]
+pub fn (t &Table) unaliased_type(typ Type) Type {
+	sym := t.sym(typ)
+	if sym.kind == .alias {
+		pt := (sym.info as Alias).parent_type
+		return pt
+	}
+	return typ
+}
+
 fn (mut t Table) rewrite_already_registered_symbol(typ TypeSymbol, existing_idx int) int {
 	existing_symbol := t.type_symbols[existing_idx]
 	if existing_symbol.kind == .placeholder {

vlib/v/checker/checker.v

@@ -4428,12 +4428,13 @@ pub fn (mut c Checker) enum_val(mut node ast.EnumVal) ast.Type {
 		typ = array_info.elem_type
 		typ_sym = c.table.sym(typ)
 	}
-	if typ_sym.kind != .enum_ && !c.pref.translated {
+	fsym := c.table.final_sym(typ)
+	if fsym.kind != .enum_ && !c.pref.translated {
 		// TODO in C int fields can be compared to enums, need to handle that in C2V
 		c.error('expected type is not an enum (`$typ_sym.name`)', node.pos)
 		return ast.void_type
 	}
-	if typ_sym.info !is ast.Enum {
+	if fsym.info !is ast.Enum {
 		c.error('not an enum', node.pos)
 		return ast.void_type
 	}

vlib/v/gen/c/cgen.v

@@ -3153,7 +3153,7 @@ fn (mut g Gen) expr(node ast.Expr) {
 		ast.EnumVal {
 			// g.write('${it.mod}${it.enum_name}_$it.val')
 			// g.enum_expr(node)
-			styp := g.typ(node.typ)
+			styp := g.typ(g.table.unaliased_type(node.typ))
 			g.write('${styp}__$node.val')
 		}
 		ast.FloatLiteral {

vlib/v/tests/enum_aliases_test.v

@@ -0,0 +1,21 @@
+enum MyEnum {
+	something
+	another
+	third
+}
+
+type MyEnumAlias = MyEnum
+
+fn test_enum_aliases() {
+	x := MyEnum.something
+	dump(x)
+	a := MyEnumAlias.something
+	dump(a)
+	assert x == a
+	//
+	dump(MyEnum.third)
+	dump(MyEnumAlias.third)
+	dump(int(MyEnum.third))
+	dump(int(MyEnumAlias.third))
+	assert MyEnum.third == MyEnumAlias.third
+}