[ruby/io-console] Store console IO in Ractor-local storage

Ractor requires a shareable class has shareable constants only, but IO
is not shareable unless frozen.

https://github.com/ruby/io-console/commit/65e0ff895c

ext/io/console/console.c

@@ -81,7 +81,7 @@ getattr(int fd, conmode *t)
 
 #define CSI "\x1b\x5b"
 
-static ID id_getc, id_console, id_close;
+static ID id_getc, id_close;
 static ID id_gets, id_flush, id_chomp_bang;
 
 #if defined HAVE_RUBY_FIBER_SCHEDULER_H
@@ -1566,6 +1566,56 @@ rb_io_closed_p(VALUE io)
 }
 #endif
 
+#ifdef HAVE_RB_EXT_RACTOR_SAFE
+#include "ruby/ractor.h"
+static rb_ractor_local_key_t key_console_dev;
+
+static bool
+console_dev_get(VALUE klass, VALUE *dev)
+{
+    return rb_ractor_local_storage_value_lookup(key_console_dev, dev);
+}
+
+static void
+console_dev_set(VALUE klass, VALUE value)
+{
+    rb_ractor_local_storage_value_set(key_console_dev, value);
+}
+
+static void
+console_dev_remove(VALUE klass)
+{
+    console_dev_set(klass, Qnil);
+}
+
+#else
+
+static ID id_console;
+
+static bool
+console_dev_get(VALUE klass, VALUE *dev)
+{
+    if (rb_const_defined(klass, id_console)) {
+	*dev = rb_const_get(klass, id_console);
+	return true;
+    }
+    return false;
+}
+
+static void
+console_dev_set(VALUE klass, VALUE value)
+{
+    rb_const_set(klass, id_console, value);
+}
+
+static void
+console_dev_remove(VALUE klass)
+{
+    rb_const_remove(klass, id_console);
+}
+
+#endif
+
 /*
  * call-seq:
  *   IO.console      -> #<File:/dev/tty>
@@ -1594,10 +1644,9 @@ console_dev(int argc, VALUE *argv, VALUE klass)
     // Force the class to be File.
     if (klass == rb_cIO) klass = rb_cFile;
 
-    if (rb_const_defined(klass, id_console)) {
+    if (console_dev_get(klass, &con)) {
-        con = rb_const_get(klass, id_console);
         if (!RB_TYPE_P(con, T_FILE) || RTEST(rb_io_closed_p(con))) {
-            rb_const_remove(klass, id_console);
+	    console_dev_remove(klass);
             con = 0;
         }
     }
@@ -1606,7 +1655,7 @@ console_dev(int argc, VALUE *argv, VALUE klass)
         if (sym == ID2SYM(id_close) && argc == 1) {
             if (con) {
                 rb_io_close(con);
-                rb_const_remove(klass, id_console);
+                console_dev_remove(klass);
                 con = 0;
             }
             return Qnil;
@@ -1647,7 +1696,7 @@ console_dev(int argc, VALUE *argv, VALUE klass)
 #ifdef CONSOLE_DEVICE_FOR_WRITING
         rb_io_set_write_io(con, out);
 #endif
-        rb_const_set(klass, id_console, con);
+        console_dev_set(klass, con);
     }
 
     if (sym) {
@@ -1769,11 +1818,15 @@ Init_console(void)
 #endif
 
 #undef rb_intern
+#ifdef HAVE_RB_EXT_RACTOR_SAFE
+    key_console_dev = rb_ractor_local_storage_value_newkey();
+#else
+    id_console = rb_intern("console");
+#endif
     id_getc = rb_intern("getc");
     id_gets = rb_intern("gets");
     id_flush = rb_intern("flush");
     id_chomp_bang = rb_intern("chomp!");
-    id_console = rb_intern("console");
     id_close = rb_intern("close");
 #define init_rawmode_opt_id(name) \
     rawmode_opt_ids[kwd_##name] = rb_intern(#name)

test/io/console/test_ractor.rb

@@ -20,5 +20,15 @@ class TestIOConsoleInRactor < Test::Unit::TestCase
       end
       puts r.take
     end;
+
+    assert_in_out_err(%W[-r#{path}], "#{<<~"begin;"}\n#{<<~'end;'}", ["true"], [])
+    begin;
+      console = IO.console
+      $VERBOSE = nil
+      r = Ractor.new do
+        IO.console
+      end
+      puts console.class == r.take.class
+    end;
   end
 end if defined? Ractor