Revert "implement String.new in Ruby"

This reverts commit fef48f0.

Author: tenderlove

string.c

@@ -50,7 +50,6 @@
 #include "shape.h"
 #include "vm_sync.h"
 #include "ruby/internal/attr/nonstring.h"
-#include "builtin.h"
 
 #if defined HAVE_CRYPT_R
 # if defined HAVE_CRYPT_H
@@ -2136,26 +2135,29 @@ rb_str_init(rb_execution_context_t *ec, VALUE str, VALUE orig, VALUE no_str, VAL
     return str;
 }
 
-/* String.new fast path: no positional argument and no keywords.
- * Returns the same empty, embedded, ASCII-8BIT string that String's alloc
- * func produces (klass is always rb_cString here; the Ruby-side dispatch
- * routes subclasses through Class#new). */
-static VALUE
-rb_str_s_new_empty(rb_execution_context_t *ec, VALUE klass)
-{
-    return empty_str_alloc(klass);
-}
-
 /* :nodoc: */
 static VALUE
-rb_str_s_new(struct rb_execution_context_struct *ec, VALUE klass, VALUE orig, VALUE no_str, VALUE encoding, VALUE no_encoding, VALUE capacity, VALUE no_capacity)
+rb_str_s_new(int argc, VALUE *argv, VALUE klass)
 {
+    if (klass != rb_cString) {
+        return rb_class_new_instance_pass_kw(argc, argv, klass);
+    }
+
+    static ID keyword_ids[2];
+    VALUE orig, opt, encoding = Qnil, capacity = Qnil;
+    VALUE kwargs[2];
     rb_encoding *enc = NULL;
-    int n = 0;
 
-    if (RTEST(no_encoding)) encoding = Qundef;
-    if (RTEST(no_capacity)) capacity = Qundef;
-    if (!RTEST(no_str)) n = 1;
+    int n = rb_scan_args(argc, argv, "01:", &orig, &opt);
+    if (NIL_P(opt)) {
+        return rb_class_new_instance_pass_kw(argc, argv, klass);
+    }
+
+    keyword_ids[0] = rb_id_encoding();
+    CONST_ID(keyword_ids[1], "capacity");
+    rb_get_kwargs(opt, keyword_ids, 0, 2, kwargs);
+    encoding = kwargs[0];
+    capacity = kwargs[1];
 
     if (n == 1) {
         orig = StringValue(orig);
@@ -12878,6 +12880,7 @@ Init_String(void)
 
     rb_include_module(rb_cString, rb_mComparable);
     rb_define_alloc_func(rb_cString, empty_str_alloc);
+    rb_define_singleton_method(rb_cString, "new", rb_str_s_new, -1);
     rb_define_singleton_method(rb_cString, "try_convert", rb_str_s_try_convert, 1);
     rb_define_method(rb_cString, "replace", rb_str_replace, 1);
     rb_define_method(rb_cString, "initialize_copy", rb_str_replace, 1);

string.rb

@@ -23,40 +23,9 @@ def ascii_only?
     Primitive.cexpr! 'rb_str_is_ascii_only_p(self)'
   end
 
-  # :nodoc:
-  def self._new(orig = (no_str = true; nil),
-                encoding: (no_encoding = true; nil),
-                capacity: (no_capacity = true; nil))
-
-    Primitive.rb_str_s_new(orig, no_str, encoding, no_encoding, capacity, no_capacity)
-  end
-  private_class_method :_new
-
   def initialize(orig = (no_str = true; nil),
                 encoding: (no_encoding = true; nil),
                 capacity: (no_capacity = true; nil))
     Primitive.rb_str_init(orig, no_str, encoding, no_encoding, capacity, no_capacity)
   end
-
-  #  call-seq:
-  #    String.new(string = ''.encode(Encoding::ASCII_8BIT), **options) -> new_string
-  #
-  #  :include: doc/string/new.rdoc
-  #
-  def self.new(...)
-    # If the receiver isn't a String, jbb
-    if Primitive.mandatory_only?
-      if String.equal?(self)
-        Primitive.rb_str_s_new_empty
-      else
-        super
-      end
-    else
-      if String.equal?(self)
-        _new(...)
-      else
-        super
-      end
-    end
-  end
 end