Some global variables can be accessed from ractors

Some global variables should be used from non-main Ractors.
[Bug #17268]

```ruby
     # ractor-local (derived from created ractor): debug
     '$DEBUG' => $DEBUG,
     '$-d' => $-d,

     # ractor-local (derived from created ractor): verbose
     '$VERBOSE' => $VERBOSE,
     '$-w' => $-w,
     '$-W' => $-W,
     '$-v' => $-v,

     # process-local (readonly): other commandline parameters
     '$-p' => $-p,
     '$-l' => $-l,
     '$-a' => $-a,

     # process-local (readonly): getpid
     '$$'  => $$,

     # thread local: process result
     '$?'  => $?,

     # scope local: match
     '$~'  => $~.inspect,
     '$&'  => $&,
     '$`'  => $`,
     '$\''  => $',
     '$+'  => $+,
     '$1'  => $1,

     # scope local: last line
     '$_' => $_,

     # scope local: last backtrace
     '$@' => $@,
     '$!' => $!,

     # ractor local: stdin, out, err
     '$stdin'  => $stdin.inspect,
     '$stdout' => $stdout.inspect,
     '$stderr' => $stderr.inspect,
```

bootstraptest/test_ractor.rb

@@ -611,6 +611,65 @@ assert_equal 'ok', %q{
   'ok'
 }
 
+# $DEBUG, $VERBOSE are Ractor local
+assert_equal 'true', %q{
+  $DEBUG = true
+  $VERBOSE = true
+
+  def ractor_local_globals
+    /a(b)(c)d/ =~ 'abcd' # for $~
+    `echo foo`
+
+    {
+     # ractor-local (derived from created ractor): debug
+     '$DEBUG' => $DEBUG,
+     '$-d' => $-d,
+
+     # ractor-local (derived from created ractor): verbose
+     '$VERBOSE' => $VERBOSE,
+     '$-w' => $-w,
+     '$-W' => $-W,
+     '$-v' => $-v,
+
+     # process-local (readonly): other commandline parameters
+     '$-p' => $-p,
+     '$-l' => $-l,
+     '$-a' => $-a,
+
+     # process-local (readonly): getpid
+     '$$'  => $$,
+
+     # thread local: process result
+     '$?'  => $?,
+
+     # scope local: match
+     '$~'  => $~.inspect,
+     '$&'  => $&,
+     '$`'  => $`,
+     '$\''  => $',
+     '$+'  => $+,
+     '$1'  => $1,
+
+     # scope local: last line
+     '$_' => $_,
+
+     # scope local: last backtrace
+     '$@' => $@,
+     '$!' => $!,
+
+     # ractor local: stdin, out, err
+     '$stdin'  => $stdin.inspect,
+     '$stdout' => $stdout.inspect,
+     '$stderr' => $stderr.inspect,
+    }
+  end
+  
+  h = Ractor.new do
+    ractor_local_globals
+  end.take
+  ractor_local_globals == h #=> true
+}
+
 # selfs are different objects
 assert_equal 'false', %q{
   r = Ractor.new do

common.mk

@@ -10943,6 +10943,7 @@ re.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 re.$(OBJEXT): $(top_srcdir)/internal/re.h
 re.$(OBJEXT): $(top_srcdir)/internal/static_assert.h
 re.$(OBJEXT): $(top_srcdir)/internal/string.h
+re.$(OBJEXT): $(top_srcdir)/internal/variable.h
 re.$(OBJEXT): $(top_srcdir)/internal/warnings.h
 re.$(OBJEXT): {$(VPATH)}assert.h
 re.$(OBJEXT): {$(VPATH)}backward/2/assume.h
@@ -10955,9 +10956,11 @@ re.$(OBJEXT): {$(VPATH)}backward/2/long_long.h
 re.$(OBJEXT): {$(VPATH)}backward/2/stdalign.h
 re.$(OBJEXT): {$(VPATH)}backward/2/stdarg.h
 re.$(OBJEXT): {$(VPATH)}config.h
+re.$(OBJEXT): {$(VPATH)}constant.h
 re.$(OBJEXT): {$(VPATH)}defines.h
 re.$(OBJEXT): {$(VPATH)}encindex.h
 re.$(OBJEXT): {$(VPATH)}encoding.h
+re.$(OBJEXT): {$(VPATH)}id_table.h
 re.$(OBJEXT): {$(VPATH)}intern.h
 re.$(OBJEXT): {$(VPATH)}internal.h
 re.$(OBJEXT): {$(VPATH)}internal/anyargs.h

eval.c

@@ -2084,6 +2084,9 @@ Init_eval(void)
     rb_define_virtual_variable("$@", errat_getter, errat_setter);
     rb_define_virtual_variable("$!", errinfo_getter, 0);
 
+    rb_gvar_ractor_local("$@");
+    rb_gvar_ractor_local("$!");
+
     rb_define_global_function("raise", f_raise, -1);
     rb_define_global_function("fail", f_raise, -1);
 

io.c

@@ -13543,6 +13543,7 @@ Init_IO(void)
     rb_define_hooked_variable("$\\", &rb_output_rs, 0, deprecated_str_setter);
 
     rb_define_virtual_variable("$_", get_LAST_READ_LINE, set_LAST_READ_LINE);
+    rb_gvar_ractor_local("$_");
 
     rb_define_method(rb_cIO, "initialize_copy", rb_io_init_copy, 1);
     rb_define_method(rb_cIO, "reopen", rb_io_reopen, -1);
@@ -13764,6 +13765,8 @@ Init_IO(void)
     ARGF.filename = rb_str_new2("-");
 
     rb_define_hooked_variable("$-i", &argf, opt_i_get, opt_i_set);
+    rb_gvar_ractor_local("$-i");
+
     rb_define_hooked_variable("$*", &argf, argf_argv_getter, rb_gvar_readonly_setter);
 
 #if defined (_WIN32) || defined(__CYGWIN__)

process.c

@@ -8445,6 +8445,10 @@ InitVM_process(void)
 #define rb_intern(str) rb_intern_const(str)
     rb_define_virtual_variable("$?", get_CHILD_STATUS, 0);
     rb_define_virtual_variable("$$", get_PROCESS_ID, 0);
+
+    rb_gvar_ractor_local("$$");
+    rb_gvar_ractor_local("$?");
+
     rb_define_global_function("exec", f_exec, -1);
     rb_define_global_function("fork", rb_f_fork, 0);
     rb_define_global_function("exit!", rb_f_exit_bang, -1);

ractor.c

@@ -1373,6 +1373,10 @@ ractor_create(rb_execution_context_t *ec, VALUE self, VALUE loc, VALUE name, VAL
     r->r_stdout = rb_io_prep_stdout();
     r->r_stderr = rb_io_prep_stderr();
 
+    rb_ractor_t *cr = rb_ec_ractor_ptr(ec);
+    r->verbose = cr->verbose;
+    r->debug = cr->debug;
+
     rb_thread_create_ractor(r, args, block);
 
     RB_GC_GUARD(rv);

ractor.h

@@ -125,6 +125,8 @@ struct rb_ractor_struct {
     VALUE r_stdin;
     VALUE r_stdout;
     VALUE r_stderr;
+    VALUE verbose;
+    VALUE debug;
 }; // rb_ractor_t is defined in vm_core.h
 
 rb_ractor_t *rb_ractor_main_alloc(void);

re.c

@@ -19,6 +19,7 @@
 #include "internal/imemo.h"
 #include "internal/re.h"
 #include "internal/string.h"
+#include "internal/variable.h"
 #include "regint.h"
 #include "ruby/encoding.h"
 #include "ruby/re.h"
@@ -4052,6 +4053,12 @@ Init_Regexp(void)
     rb_define_virtual_variable("$'", postmatch_getter, 0);
     rb_define_virtual_variable("$+", last_paren_match_getter, 0);
 
+    rb_gvar_ractor_local("$~");
+    rb_gvar_ractor_local("$&");
+    rb_gvar_ractor_local("$`");
+    rb_gvar_ractor_local("$'");
+    rb_gvar_ractor_local("$+");
+
     rb_define_virtual_variable("$=", ignorecase_getter, ignorecase_setter);
     rb_define_virtual_variable("$KCODE", kcode_getter, kcode_setter);
     rb_define_virtual_variable("$-K", kcode_getter, kcode_setter);

ruby.c

@@ -63,6 +63,7 @@
 #include "ruby/thread.h"
 #include "ruby/util.h"
 #include "ruby/version.h"
+#include "ruby/internal/error.h"
 
 #ifndef MAXPATHLEN
 # define MAXPATHLEN 1024
@@ -2021,6 +2022,10 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
     rb_define_readonly_boolean("$-l", opt->do_line);
     rb_define_readonly_boolean("$-a", opt->do_split);
 
+    rb_gvar_ractor_local("$-p");
+    rb_gvar_ractor_local("$-l");
+    rb_gvar_ractor_local("$-a");
+
     if ((rb_e_script = opt->e_script) != 0) {
         rb_gc_register_mark_object(opt->e_script);
     }
@@ -2430,16 +2435,24 @@ forbid_setid(const char *s, const ruby_cmdline_options_t *opt)
         rb_raise(rb_eSecurityError, "no %s allowed while running setgid", s);
 }
 
+static VALUE
+verbose_getter(ID id, VALUE *ptr)
+{
+    return *rb_ruby_verbose_ptr();
+}
+
 static void
 verbose_setter(VALUE val, ID id, VALUE *variable)
 {
-    *variable = RTEST(val) ? Qtrue : val;
+    *rb_ruby_verbose_ptr() = RTEST(val) ? Qtrue : val;
 }
 
 static VALUE
-opt_W_getter(ID id, VALUE *variable)
+opt_W_getter(ID id, VALUE *dmy)
 {
-    switch (*variable) {
+    VALUE v = *rb_ruby_verbose_ptr();
+
+    switch (v) {
       case Qnil:
 	return INT2FIX(0);
       case Qfalse:
@@ -2451,16 +2464,35 @@ opt_W_getter(ID id, VALUE *variable)
     }
 }
 
+static VALUE
+debug_getter(ID id, VALUE *dmy)
+{
+    return *rb_ruby_debug_ptr();
+}
+
+static void
+debug_setter(VALUE val, ID id, VALUE *dmy)
+{
+    *rb_ruby_debug_ptr() = val;
+}
+
 /*! Defines built-in variables */
 void
 ruby_prog_init(void)
 {
-    rb_define_hooked_variable("$VERBOSE", &ruby_verbose, 0, verbose_setter);
-    rb_define_hooked_variable("$-v", &ruby_verbose, 0, verbose_setter);
-    rb_define_hooked_variable("$-w", &ruby_verbose, 0, verbose_setter);
-    rb_define_hooked_variable("$-W", &ruby_verbose, opt_W_getter, rb_gvar_readonly_setter);
-    rb_define_variable("$DEBUG", &ruby_debug);
-    rb_define_variable("$-d", &ruby_debug);
+    rb_define_virtual_variable("$VERBOSE", verbose_getter, verbose_setter);
+    rb_define_virtual_variable("$-v",      verbose_getter, verbose_setter);
+    rb_define_virtual_variable("$-w",      verbose_getter, verbose_setter);
+    rb_define_virtual_variable("$-W",      opt_W_getter,   rb_gvar_readonly_setter);
+    rb_define_virtual_variable("$DEBUG",   debug_getter,   debug_setter);
+    rb_define_virtual_variable("$-d",      debug_getter,   debug_setter);
+
+    rb_gvar_ractor_local("$VERBOSE");
+    rb_gvar_ractor_local("$-v");
+    rb_gvar_ractor_local("$-w");
+    rb_gvar_ractor_local("$-W");
+    rb_gvar_ractor_local("$DEBUG");
+    rb_gvar_ractor_local("$-d");
 
     rb_define_hooked_variable("$0", &rb_progname, 0, set_arg0);
     rb_define_hooked_variable("$PROGRAM_NAME", &rb_progname, 0, set_arg0);

vm.c

@@ -3515,28 +3515,18 @@ Init_top_self(void)
     rb_define_alias(rb_singleton_class(rb_vm_top_self()), "inspect", "to_s");
 }
 
-static VALUE *
-ruby_vm_verbose_ptr(rb_vm_t *vm)
-{
-    return &vm->verbose;
-}
-
-static VALUE *
-ruby_vm_debug_ptr(rb_vm_t *vm)
-{
-    return &vm->debug;
-}
-
 VALUE *
 rb_ruby_verbose_ptr(void)
 {
-    return ruby_vm_verbose_ptr(GET_VM());
+    rb_ractor_t *cr = GET_RACTOR();
+    return &cr->verbose;
 }
 
 VALUE *
 rb_ruby_debug_ptr(void)
 {
-    return ruby_vm_debug_ptr(GET_VM());
+    rb_ractor_t *cr = GET_RACTOR();
+    return &cr->debug;
 }
 
 /* iseq.c */

vm_core.h

@@ -633,7 +633,7 @@ typedef struct rb_vm_struct {
     struct list_head workqueue; /* <=> rb_workqueue_job.jnode */
     rb_nativethread_lock_t workqueue_lock;
 
-    VALUE verbose, debug, orig_progname, progname;
+    VALUE orig_progname, progname;
     VALUE coverages;
     int coverage_mode;