checker: fix appending an .enum_val to a struct field of []Enum

vlib/v/checker/checker.v

@@ -2229,15 +2229,20 @@ pub fn (mut c Checker) enum_val(mut node ast.EnumVal) table.Type {
 		c.error('not an enum (name=$node.enum_name) (type_idx=0)', node.pos)
 		return table.void_type
 	}
-	typ := table.new_type(typ_idx)
+	mut typ := table.new_type(typ_idx)
 	if typ == table.void_type {
 		c.error('not an enum', node.pos)
 		return table.void_type
 	}
-	typ_sym := c.table.get_type_symbol(typ)
+	mut typ_sym := c.table.get_type_symbol(typ)
 	// println('tname=$typ_sym.name $node.pos.line_nr $c.file.path')
+	if typ_sym.kind == .array && node.enum_name.len == 0 {
+		array_info := typ_sym.info as table.Array
+		typ = array_info.elem_type
+		typ_sym = c.table.get_type_symbol(typ)
+	}
 	if typ_sym.kind != .enum_ {
-		c.error('not an enum', node.pos)
+		c.error('expected type is not an enum', node.pos)
 		return table.void_type
 	}
 	if !(typ_sym.info is table.Enum) {

vlib/v/tests/enum_array_field_test.v

@@ -0,0 +1,20 @@
+struct Abc {
+mut:
+    flags []Flag
+}
+
+enum Flag {
+    flag_one
+    flag_two
+}
+
+fn test_enum_array_field() {
+    mut a := Abc{}
+    a.flags << .flag_one
+    assert true
+    a.flags << .flag_two
+    assert true
+    a.flags << .flag_one
+    println(a)
+    assert true
+}