Fix class name validation in `Struct.new`

Before this patch:

  $ bin/mruby -e 'p Struct.new("A-")'
  #=> Struct::"A-"

After this patch:

  $ bin/mruby -e 'p Struct.new("A-")'
  #=> NameError: identifier A- needs to be constant

2 files changed, 5 insertions, 1 deletions

diff --git a/mrbgems/mruby-struct/src/struct.c b/mrbgems/mruby-struct/src/struct.c
index 1df135a9f..539127bf8 100644
--- a/mrbgems/mruby-struct/src/struct.c
+++ b/mrbgems/mruby-struct/src/struct.c
@@ -212,7 +212,7 @@ make_struct(mrb_state *mrb, mrb_value name, mrb_value members, struct RClass *kl
     /* old style: should we warn? */
     mrb_to_str(mrb, name);
     id = mrb_obj_to_sym(mrb, name);
-    if (!is_const_id(mrb, mrb_sym2name_len(mrb, id, NULL))) {
+    if (!mrb_const_name_p(mrb, RSTRING_PTR(name), RSTRING_LEN(name))) {
       mrb_name_error(mrb, id, "identifier %S needs to be constant", name);
     }
     if (mrb_const_defined_at(mrb, mrb_obj_value(klass), id)) {
diff --git a/mrbgems/mruby-struct/test/struct.rb b/mrbgems/mruby-struct/test/struct.rb
index 91e8cecc6..9f2ff1cdc 100644
--- a/mrbgems/mruby-struct/test/struct.rb
+++ b/mrbgems/mruby-struct/test/struct.rb
@@ -181,6 +181,10 @@ assert("Struct.new does not allow array") do
   end
 end
 
+assert("Struct.new does not allow invalid class name") do
+  assert_raise(NameError) { Struct.new("Test-", :a) }
+end
+
 assert("Struct.new generates subclass of Struct") do
   begin
     original_struct = Struct