object.c: introduce `mrb_ensure_{int,float}_type`.

Since `mrb_to_integer` and `mrb_to_float` does not convert the object
but checks types, they are named so by historical reason. We introduced
properly named functions.

This commit obsoletes the following functions:

* mrb_to_integer()
* mrb_to_int()
* mrb_to_float()

Use `mrb_ensure_int_type()` instead for the first 2 functions. Use
`mrb_ensure_float_type()` for the last.

include/mruby.h

@@ -1269,7 +1269,9 @@ MRB_API mrb_bool mrb_obj_eq(mrb_state *mrb, mrb_value a, mrb_value b);
 MRB_API mrb_bool mrb_obj_equal(mrb_state *mrb, mrb_value a, mrb_value b);
 MRB_API mrb_bool mrb_equal(mrb_state *mrb, mrb_value obj1, mrb_value obj2);
 #ifndef MRB_NO_FLOAT
-MRB_API mrb_value mrb_to_float(mrb_state *mrb, mrb_value val);
+MRB_API mrb_value mrb_ensure_float_type(mrb_state *mrb, mrb_value val);
+/* obsolete: use mrb_ensure_float_type() instead */
+#define mrb_to_float(mrb, val) mrb_ensure_float_type(mrb, val)
 #endif
 MRB_API mrb_value mrb_inspect(mrb_state *mrb, mrb_value obj);
 MRB_API mrb_bool mrb_eql(mrb_state *mrb, mrb_value obj1, mrb_value obj2);
@@ -1398,9 +1400,11 @@ MRB_API mrb_value mrb_check_string_type(mrb_state *mrb, mrb_value str);
 #define mrb_to_str(mrb, str) mrb_ensure_string_type(mrb,str)
 /* obsolete: use mrb_obj_as_string() instead */
 #define mrb_str_to_str(mrb, str) mrb_obj_as_string(mrb, str)
-MRB_API mrb_value mrb_to_integer(mrb_state *mrb, mrb_value val);
-#define mrb_to_int(mrb, val) mrb_to_integer(mrb, val)
-#define mrb_as_int(mrb, val) mrb_integer(mrb_to_integer(mrb, val))
+MRB_API mrb_value mrb_ensure_int_type(mrb_state *mrb, mrb_value val);
+#define mrb_as_int(mrb, val) mrb_integer(mrb_ensure_int_type(mrb, val))
+/* obsolete: use mrb_ensure_int_type() instead */
+#define mrb_to_integer(mrb, val) mrb_ensure_int_type(mrb, val)
+#define mrb_to_int(mrb, val) mrb_ensure_int_type(mrb, val)
 
 /* string type checking (contrary to the name, it doesn't convert) */
 MRB_API void mrb_check_type(mrb_state *mrb, mrb_value x, enum mrb_vtype t);

src/kernel.c

@@ -659,7 +659,7 @@ mrb_init_kernel(mrb_state *mrb)
   mrb_define_method(mrb, krn, "respond_to?",                obj_respond_to,                  MRB_ARGS_ARG(1,1));     /* 15.3.1.3.43 */
   mrb_define_method(mrb, krn, "to_s",                       mrb_any_to_s,                    MRB_ARGS_NONE());    /* 15.3.1.3.46 */
   mrb_define_method(mrb, krn, "__case_eqq",                 mrb_obj_ceqq,                    MRB_ARGS_REQ(1));    /* internal */
-  mrb_define_method(mrb, krn, "__to_int",                   mrb_to_integer,                  MRB_ARGS_NONE());    /* internal */
+  mrb_define_method(mrb, krn, "__to_int",                   mrb_ensure_int_type,             MRB_ARGS_NONE());    /* internal */
   mrb_define_method(mrb, krn, "__ENCODING__",               mrb_encoding,                    MRB_ARGS_NONE());
 
   mrb_include_module(mrb, mrb->object_class, mrb->kernel_module);

src/object.c

@@ -485,7 +485,7 @@ mrb_obj_is_kind_of(mrb_state *mrb, mrb_value obj, struct RClass *c)
 }
 
 MRB_API mrb_value
-mrb_to_integer(mrb_state *mrb, mrb_value val)
+mrb_ensure_int_type(mrb_state *mrb, mrb_value val)
 {
   if (!mrb_integer_p(val)) {
 #ifndef MRB_NO_FLOAT
@@ -500,7 +500,7 @@ mrb_to_integer(mrb_state *mrb, mrb_value val)
 
 #ifndef MRB_NO_FLOAT
 MRB_API mrb_value
-mrb_to_float(mrb_state *mrb, mrb_value val)
+mrb_ensure_float_type(mrb_state *mrb, mrb_value val)
 {
   if (mrb_nil_p(val)) {
     mrb_raise(mrb, E_TYPE_ERROR, "can't convert nil into Float");