Merge pull request #2852 from jbreeden/mrb_string_value_cstr_patch

Mrb string value cstr patch

src/string.c

@@ -1985,7 +1985,8 @@ bad:
 MRB_API const char*
 mrb_string_value_cstr(mrb_state *mrb, mrb_value *ptr)
 {
-  struct RString *ps = mrb_str_ptr(*ptr);
+  mrb_value str = mrb_str_to_str(mrb, *ptr);
+  struct RString *ps = mrb_str_ptr(str);
   mrb_int len = mrb_str_strlen(mrb, ps);
   char *p = RSTR_PTR(ps);
 
@@ -2002,12 +2003,12 @@ mrb_str_to_inum(mrb_state *mrb, mrb_value str, mrb_int base, mrb_bool badcheck)
   const char *s;
   mrb_int len;
 
-  str = mrb_str_to_str(mrb, str);
   if (badcheck) {
+    /* Raises if the string contains a null character (the badcheck) */
     s = mrb_string_value_cstr(mrb, &str);
   }
   else {
-    s = RSTRING_PTR(str);
+    s = mrb_string_value_ptr(mrb, str);
   }
   if (s) {
     len = RSTRING_LEN(str);