Correct argument specifications for few methods:

 - Struct#values_at
 - Module#define_method
 - String#chop
 - String#chop!

mrbgems/mruby-struct/src/struct.c

@@ -703,7 +703,7 @@ mrb_mruby_struct_gem_init(mrb_state* mrb)
   mrb_define_method(mrb, st,        "to_a",           mrb_struct_to_a,        MRB_ARGS_NONE());
   mrb_define_method(mrb, st,        "values",         mrb_struct_to_a,        MRB_ARGS_NONE());
   mrb_define_method(mrb, st,        "to_h",           mrb_struct_to_h,        MRB_ARGS_NONE());
-  mrb_define_method(mrb, st,        "values_at",      mrb_struct_values_at,   MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "values_at",      mrb_struct_values_at,   MRB_ARGS_ANY());
 }
 
 void

src/class.c

@@ -2287,7 +2287,7 @@ mrb_init_class(mrb_state *mrb)
   mrb_define_method(mrb, mod, "constants",               mrb_mod_constants,        MRB_ARGS_OPT(1)); /* 15.2.2.4.24 */
   mrb_define_method(mrb, mod, "remove_const",            mrb_mod_remove_const,     MRB_ARGS_REQ(1)); /* 15.2.2.4.40 */
   mrb_define_method(mrb, mod, "const_missing",           mrb_mod_const_missing,    MRB_ARGS_REQ(1));
-  mrb_define_method(mrb, mod, "define_method",           mod_define_method,        MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, mod, "define_method",           mod_define_method,        MRB_ARGS_ARG(1,1));
   mrb_define_method(mrb, mod, "class_variables",         mrb_mod_class_variables,  MRB_ARGS_NONE()); /* 15.2.2.4.19 */
   mrb_define_method(mrb, mod, "===",                     mrb_mod_eqq,              MRB_ARGS_REQ(1));
   mrb_define_class_method(mrb, mod, "constants",         mrb_mod_s_constants,      MRB_ARGS_ANY());  /* 15.2.2.3.1 */

src/string.c

@@ -2723,8 +2723,8 @@ mrb_init_string(mrb_state *mrb)
   mrb_define_method(mrb, s, "capitalize!",     mrb_str_capitalize_bang, MRB_ARGS_NONE()); /* 15.2.10.5.8  */
   mrb_define_method(mrb, s, "chomp",           mrb_str_chomp,           MRB_ARGS_ANY());  /* 15.2.10.5.9  */
   mrb_define_method(mrb, s, "chomp!",          mrb_str_chomp_bang,      MRB_ARGS_ANY());  /* 15.2.10.5.10 */
-  mrb_define_method(mrb, s, "chop",            mrb_str_chop,            MRB_ARGS_REQ(1)); /* 15.2.10.5.11 */
-  mrb_define_method(mrb, s, "chop!",           mrb_str_chop_bang,       MRB_ARGS_REQ(1)); /* 15.2.10.5.12 */
+  mrb_define_method(mrb, s, "chop",            mrb_str_chop,            MRB_ARGS_NONE()); /* 15.2.10.5.11 */
+  mrb_define_method(mrb, s, "chop!",           mrb_str_chop_bang,       MRB_ARGS_NONE()); /* 15.2.10.5.12 */
   mrb_define_method(mrb, s, "downcase",        mrb_str_downcase,        MRB_ARGS_NONE()); /* 15.2.10.5.13 */
   mrb_define_method(mrb, s, "downcase!",       mrb_str_downcase_bang,   MRB_ARGS_NONE()); /* 15.2.10.5.14 */
   mrb_define_method(mrb, s, "empty?",          mrb_str_empty_p,         MRB_ARGS_NONE()); /* 15.2.10.5.16 */