eval.c

/**********************************************************************

  eval.c -

  $Author$
  created at: Thu Jun 10 14:22:17 JST 1993

  Copyright (C) 1993-2007 Yukihiro Matsumoto
  Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
  Copyright (C) 2000  Information-technology Promotion Agency, Japan

**********************************************************************/

#include "ruby/internal/config.h"

#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif

#include "eval_intern.h"
#include "internal.h"
#include "internal/class.h"
#include "internal/cont.h"
#include "internal/error.h"
#include "internal/eval.h"
#include "internal/gc.h"
#include "internal/hash.h"
#include "internal/inits.h"
#include "internal/io.h"
#include "internal/object.h"
#include "internal/thread.h"
#include "internal/variable.h"
#include "ruby/fiber/scheduler.h"
#include "iseq.h"
#include "rjit.h"
#include "probes.h"
#include "probes_helper.h"
#include "ruby/vm.h"
#include "vm_core.h"
#include "ractor_core.h"

NORETURN(static void rb_raise_jump(VALUE, VALUE));
void rb_ec_clear_current_thread_trace_func(const rb_execution_context_t *ec);
void rb_ec_clear_all_trace_func(const rb_execution_context_t *ec);

static int rb_ec_cleanup(rb_execution_context_t *ec, enum ruby_tag_type ex);
static int rb_ec_exec_node(rb_execution_context_t *ec, void *n);

VALUE rb_eLocalJumpError;
VALUE rb_eSysStackError;

ID ruby_static_id_signo, ruby_static_id_status;
extern ID ruby_static_id_cause;
#define id_cause ruby_static_id_cause

#define exception_error GET_VM()->special_exceptions[ruby_error_reenter]

#include "eval_error.c"
#include "eval_jump.c"

#define CLASS_OR_MODULE_P(obj) \
    (!SPECIAL_CONST_P(obj) && \
     (BUILTIN_TYPE(obj) == T_CLASS || BUILTIN_TYPE(obj) == T_MODULE))

int
ruby_setup(void)
{
    enum ruby_tag_type state;

    if (GET_VM())
        return 0;

    /*
     * Disable THP early before mallocs happen because we want this to
     * affect as many future pages as possible for CoW-friendliness
     */
#if defined(__linux__) && defined(PR_SET_THP_DISABLE)
    prctl(PR_SET_THP_DISABLE, 1, 0, 0, 0);
#endif
    Init_BareVM();
    rb_vm_encoded_insn_data_table_init();
    Init_vm_objects();

    EC_PUSH_TAG(GET_EC());
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        rb_call_inits();
        ruby_prog_init();
        GET_VM()->running = 1;
    }
    EC_POP_TAG();

    return state;
}

void
ruby_init(void)
{
    int state = ruby_setup();
    if (state) {
        if (RTEST(ruby_debug)) {
            rb_execution_context_t *ec = GET_EC();
            rb_ec_error_print(ec, ec->errinfo);
        }
        exit(EXIT_FAILURE);
    }
}

void *
ruby_options(int argc, char **argv)
{
    rb_execution_context_t *ec = GET_EC();
    enum ruby_tag_type state;
    void *volatile iseq = 0;

    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        iseq = ruby_process_options(argc, argv);
    }
    else {
        rb_ec_clear_current_thread_trace_func(ec);
        int exitcode = error_handle(ec, ec->errinfo, state);
        ec->errinfo = Qnil; /* just been handled */
        iseq = (void *)INT2FIX(exitcode);
    }
    EC_POP_TAG();
    return iseq;
}

static void
rb_ec_fiber_scheduler_finalize(rb_execution_context_t *ec)
{
    enum ruby_tag_type state;

    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        rb_fiber_scheduler_set(Qnil);
    }
    else {
        state = error_handle(ec, ec->errinfo, state);
    }
    EC_POP_TAG();
}

static void
rb_ec_teardown(rb_execution_context_t *ec)
{
    // If the user code defined a scheduler for the top level thread, run it:
    rb_ec_fiber_scheduler_finalize(ec);

    EC_PUSH_TAG(ec);
    if (EC_EXEC_TAG() == TAG_NONE) {
        rb_vm_trap_exit(rb_ec_vm_ptr(ec));
    }
    EC_POP_TAG();
    rb_ec_exec_end_proc(ec);
    rb_ec_clear_all_trace_func(ec);
}

static void
rb_ec_finalize(rb_execution_context_t *ec)
{
    ruby_sig_finalize();
    ec->errinfo = Qnil;
    rb_objspace_call_finalizer();
}

void
ruby_finalize(void)
{
    rb_execution_context_t *ec = GET_EC();
    rb_ec_teardown(ec);
    rb_ec_finalize(ec);
}

int
ruby_cleanup(int ex)
{
    return rb_ec_cleanup(GET_EC(), (enum ruby_tag_type)ex);
}

static int
rb_ec_cleanup(rb_execution_context_t *ec, enum ruby_tag_type ex)
{
    int state;
    volatile VALUE save_error = Qundef;
    volatile int sysex = EXIT_SUCCESS;
    volatile int signaled = 0;
    rb_thread_t *th = rb_ec_thread_ptr(ec);
    rb_thread_t *const volatile th0 = th;
    volatile int step = 0;
    volatile VALUE message = Qnil;
    VALUE buf;

    rb_threadptr_interrupt(th);
    rb_threadptr_check_signal(th);

    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        RUBY_VM_CHECK_INTS(ec);

      step_0: step++;
        save_error = ec->errinfo;
        if (THROW_DATA_P(ec->errinfo)) ec->errinfo = Qnil;

        /* exits with failure but silently when an exception raised
         * here */
        rb_ec_teardown(ec);

      step_1: step++;
        VALUE err = ec->errinfo;
        volatile int mode0 = 0, mode1 = 0;
        if (err != save_error && !NIL_P(err)) {
            mode0 = exiting_split(err, &sysex, &signaled);
        }

        /* exceptions after here will be ignored */

        /* build error message including causes */
        err = ATOMIC_VALUE_EXCHANGE(save_error, Qnil);

        if (!NIL_P(err) && !THROW_DATA_P(err)) {
            mode1 = exiting_split(err, (mode0 & EXITING_WITH_STATUS) ? NULL : &sysex, &signaled);
            if (mode1 & EXITING_WITH_MESSAGE) {
                buf = rb_str_new(NULL, 0);
                rb_ec_error_print_detailed(ec, err, buf, Qundef);
                message = buf;
            }
        }

      step_2: step++;
        /* protect from Thread#raise */
        th->status = THREAD_KILLED;

        rb_ractor_terminate_all();

      step_3: step++;
        if (!NIL_P(buf = message)) {
            warn_print_str(buf);
        }
        else if (!NIL_OR_UNDEF_P(err = save_error) ||
                 (ex != TAG_NONE && !((mode0|mode1) & EXITING_WITH_STATUS))) {
            sysex = error_handle(ec, err, ex);
        }
    }
    else {
        th = th0;
        switch (step) {
          case 0: goto step_0;
          case 1: goto step_1;
          case 2: goto step_2;
          case 3: goto step_3;
        }
    }

    rb_ec_finalize(ec);

    /* unlock again if finalizer took mutexes. */
    rb_threadptr_unlock_all_locking_mutexes(th);
    th = th0;
    EC_POP_TAG();
    th = th0;
    rb_thread_stop_timer_thread();
    ruby_vm_destruct(th->vm);
    // For YJIT, call this after ruby_vm_destruct() frees jit_cont for the root fiber.
    rb_jit_cont_finish();

    if (signaled) ruby_default_signal(signaled);

    return sysex;
}

static int
rb_ec_exec_node(rb_execution_context_t *ec, void *n)
{
    volatile int state;
    rb_iseq_t *iseq = (rb_iseq_t *)n;
    if (!n) return 0;

    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        rb_iseq_eval_main(iseq);
    }
    EC_POP_TAG();
    return state;
}

void
ruby_stop(int ex)
{
    exit(ruby_cleanup(ex));
}

int
ruby_executable_node(void *n, int *status)
{
    VALUE v = (VALUE)n;
    int s;

    switch (v) {
      case Qtrue:  s = EXIT_SUCCESS; break;
      case Qfalse: s = EXIT_FAILURE; break;
      default:
        if (!FIXNUM_P(v)) return TRUE;
        s = FIX2INT(v);
    }
    if (status) *status = s;
    return FALSE;
}

int
ruby_run_node(void *n)
{
    rb_execution_context_t *ec = GET_EC();
    int status;
    if (!ruby_executable_node(n, &status)) {
        rb_ec_cleanup(ec, (NIL_P(ec->errinfo) ? TAG_NONE : TAG_RAISE));
        return status;
    }
    return rb_ec_cleanup(ec, rb_ec_exec_node(ec, n));
}

int
ruby_exec_node(void *n)
{
    return rb_ec_exec_node(GET_EC(), n);
}

/*
 *  call-seq:
 *     Module.nesting    -> array
 *
 *  Returns the list of +Modules+ nested at the point of call.
 *
 *     module M1
 *       module M2
 *         $a = Module.nesting
 *       end
 *     end
 *     $a           #=> [M1::M2, M1]
 *     $a[0].name   #=> "M1::M2"
 */

static VALUE
rb_mod_nesting(VALUE _)
{
    VALUE ary = rb_ary_new();
    const rb_cref_t *cref = rb_vm_cref();

    while (cref && CREF_NEXT(cref)) {
        VALUE klass = CREF_CLASS(cref);
        if (!CREF_PUSHED_BY_EVAL(cref) &&
            !NIL_P(klass)) {
            rb_ary_push(ary, klass);
        }
        cref = CREF_NEXT(cref);
    }
    return ary;
}

/*
 *  call-seq:
 *     Module.constants   -> array
 *     Module.constants(inherited)   -> array
 *
 *  In the first form, returns an array of the names of all
 *  constants accessible from the point of call.
 *  This list includes the names of all modules and classes
 *  defined in the global scope.
 *
 *     Module.constants.first(4)
 *        # => [:ARGF, :ARGV, :ArgumentError, :Array]
 *
 *     Module.constants.include?(:SEEK_SET)   # => false
 *
 *     class IO
 *       Module.constants.include?(:SEEK_SET) # => true
 *     end
 *
 *  The second form calls the instance method +constants+.
 */

static VALUE
rb_mod_s_constants(int argc, VALUE *argv, VALUE mod)
{
    const rb_cref_t *cref = rb_vm_cref();
    VALUE klass;
    VALUE cbase = 0;
    void *data = 0;

    if (argc > 0 || mod != rb_cModule) {
        return rb_mod_constants(argc, argv, mod);
    }

    while (cref) {
        klass = CREF_CLASS(cref);
        if (!CREF_PUSHED_BY_EVAL(cref) &&
            !NIL_P(klass)) {
            data = rb_mod_const_at(CREF_CLASS(cref), data);
            if (!cbase) {
                cbase = klass;
            }
        }
        cref = CREF_NEXT(cref);
    }

    if (cbase) {
        data = rb_mod_const_of(cbase, data);
    }
    return rb_const_list(data);
}

/**
 * Asserts that `klass` is not a frozen class.
 * @param[in] klass a `Module` object
 * @exception RuntimeError if `klass` is not a class or frozen.
 * @ingroup class
 */
void
rb_class_modify_check(VALUE klass)
{
    if (SPECIAL_CONST_P(klass)) {
        Check_Type(klass, T_CLASS);
    }
    if (RB_TYPE_P(klass, T_MODULE)) {
        rb_module_set_initialized(klass);
    }
    if (OBJ_FROZEN(klass)) {
        const char *desc;

        if (RCLASS_SINGLETON_P(klass)) {
            desc = "object";
            klass = RCLASS_ATTACHED_OBJECT(klass);
            if (!SPECIAL_CONST_P(klass)) {
                switch (BUILTIN_TYPE(klass)) {
                  case T_MODULE:
                  case T_ICLASS:
                    desc = "Module";
                    break;
                  case T_CLASS:
                    desc = "Class";
                    break;
                  default:
                    break;
                }
            }
        }
        else {
            switch (BUILTIN_TYPE(klass)) {
              case T_MODULE:
              case T_ICLASS:
                desc = "module";
                break;
              case T_CLASS:
                desc = "class";
                break;
              default:
                Check_Type(klass, T_CLASS);
                UNREACHABLE;
            }
        }
        rb_frozen_error_raise(klass, "can't modify frozen %s: %"PRIsVALUE, desc, klass);
    }
}

NORETURN(static void rb_longjmp(rb_execution_context_t *, enum ruby_tag_type, volatile VALUE, VALUE));
static VALUE get_errinfo(void);
#define get_ec_errinfo(ec) rb_ec_get_errinfo(ec)

static VALUE
exc_setup_cause(VALUE exc, VALUE cause)
{
#if OPT_SUPPORT_JOKE
    if (NIL_P(cause)) {
        ID id_true_cause;
        CONST_ID(id_true_cause, "true_cause");

        cause = rb_attr_get(rb_eFatal, id_true_cause);
        if (NIL_P(cause)) {
            cause = rb_exc_new_cstr(rb_eFatal, "because using such Ruby");
            rb_ivar_set(cause, id_cause, INT2FIX(42)); /* the answer */
            OBJ_FREEZE(cause);
            rb_ivar_set(rb_eFatal, id_true_cause, cause);
        }
    }
#endif
    if (!NIL_P(cause) && cause != exc) {
        rb_ivar_set(exc, id_cause, cause);
        if (!rb_ivar_defined(cause, id_cause)) {
            rb_ivar_set(cause, id_cause, Qnil);
        }
    }
    return exc;
}

static inline VALUE
exc_setup_message(const rb_execution_context_t *ec, VALUE mesg, VALUE *cause)
{
    int nocause = 0;
    int nocircular = 0;

    if (NIL_P(mesg)) {
        mesg = ec->errinfo;
        if (INTERNAL_EXCEPTION_P(mesg)) EC_JUMP_TAG(ec, TAG_FATAL);
        nocause = 1;
    }
    if (NIL_P(mesg)) {
        mesg = rb_exc_new(rb_eRuntimeError, 0, 0);
        nocause = 0;
        nocircular = 1;
    }
    if (UNDEF_P(*cause)) {
        if (nocause) {
            *cause = Qnil;
            nocircular = 1;
        }
        else if (!rb_ivar_defined(mesg, id_cause)) {
            *cause = get_ec_errinfo(ec);
        }
        else {
            nocircular = 1;
        }
    }
    else if (!NIL_P(*cause) && !rb_obj_is_kind_of(*cause, rb_eException)) {
        rb_raise(rb_eTypeError, "exception object expected");
    }

    if (!nocircular && !NIL_P(*cause) && !UNDEF_P(*cause) && *cause != mesg) {
#if 0 /* maybe critical for some cases */
        rb_exc_check_circular_cause(*cause);
#else
        VALUE c = *cause;
        while (!NIL_P(c = rb_attr_get(c, id_cause))) {
            if (c == mesg) {
                rb_raise(rb_eArgError, "circular causes");
            }
        }
#endif
    }
    return mesg;
}

static void
setup_exception(rb_execution_context_t *ec, enum ruby_tag_type tag, volatile VALUE mesg, VALUE cause)
{
    VALUE e;
    int line;
    const char *file = rb_source_location_cstr(&line);
    const char *const volatile file0 = file;

    if ((file && !NIL_P(mesg)) || !UNDEF_P(cause))  {
        volatile int state = 0;

        EC_PUSH_TAG(ec);
        if (EC_EXEC_TAG() == TAG_NONE && !(state = rb_ec_set_raised(ec))) {
            VALUE bt = rb_get_backtrace(mesg);
            if (!NIL_P(bt) || UNDEF_P(cause)) {
                if (OBJ_FROZEN(mesg)) {
                    mesg = rb_obj_dup(mesg);
                }
            }
            if (!UNDEF_P(cause) && !THROW_DATA_P(cause)) {
                exc_setup_cause(mesg, cause);
            }
            if (NIL_P(bt)) {
                VALUE at = rb_ec_backtrace_object(ec);
                rb_ivar_set(mesg, idBt_locations, at);
                set_backtrace(mesg, at);
            }
            rb_ec_reset_raised(ec);
        }
        EC_POP_TAG();
        file = file0;
        if (state) goto fatal;
    }

    if (!NIL_P(mesg)) {
        ec->errinfo = mesg;
    }

    if (RTEST(ruby_debug) && !NIL_P(e = ec->errinfo) &&
        !rb_obj_is_kind_of(e, rb_eSystemExit)) {
        enum ruby_tag_type state;

        mesg = e;
        EC_PUSH_TAG(ec);
        if ((state = EC_EXEC_TAG()) == TAG_NONE) {
            ec->errinfo = Qnil;
            e = rb_obj_as_string(mesg);
            ec->errinfo = mesg;
            if (file && line) {
                e = rb_sprintf("Exception '%"PRIsVALUE"' at %s:%d - %"PRIsVALUE"\n",
                               rb_obj_class(mesg), file, line, e);
            }
            else if (file) {
                e = rb_sprintf("Exception '%"PRIsVALUE"' at %s - %"PRIsVALUE"\n",
                               rb_obj_class(mesg), file, e);
            }
            else {
                e = rb_sprintf("Exception '%"PRIsVALUE"' - %"PRIsVALUE"\n",
                               rb_obj_class(mesg), e);
            }
            warn_print_str(e);
        }
        EC_POP_TAG();
        if (state == TAG_FATAL && ec->errinfo == exception_error) {
            ec->errinfo = mesg;
        }
        else if (state) {
            rb_ec_reset_raised(ec);
            EC_JUMP_TAG(ec, state);
        }
    }

    if (rb_ec_set_raised(ec)) {
        goto fatal;
    }

    if (tag != TAG_FATAL) {
        RUBY_DTRACE_HOOK(RAISE, rb_obj_classname(ec->errinfo));
        EXEC_EVENT_HOOK(ec, RUBY_EVENT_RAISE, ec->cfp->self, 0, 0, 0, mesg);
    }
    return;

  fatal:
    ec->errinfo = exception_error;
    rb_ec_reset_raised(ec);
    EC_JUMP_TAG(ec, TAG_FATAL);
}

/*! \private */
void
rb_ec_setup_exception(const rb_execution_context_t *ec, VALUE mesg, VALUE cause)
{
    if (UNDEF_P(cause)) {
        cause = get_ec_errinfo(ec);
    }
    if (cause != mesg) {
        if (THROW_DATA_P(cause)) {
            cause = Qnil;
        }

        rb_ivar_set(mesg, id_cause, cause);
    }
}

static void
rb_longjmp(rb_execution_context_t *ec, enum ruby_tag_type tag, volatile VALUE mesg, VALUE cause)
{
    mesg = exc_setup_message(ec, mesg, &cause);
    setup_exception(ec, tag, mesg, cause);
    rb_ec_raised_clear(ec);
    EC_JUMP_TAG(ec, tag);
}

static VALUE make_exception(int argc, const VALUE *argv, int isstr);

NORETURN(static void rb_exc_exception(VALUE mesg, enum ruby_tag_type tag, VALUE cause));

static void
rb_exc_exception(VALUE mesg, enum ruby_tag_type tag, VALUE cause)
{
    if (!NIL_P(mesg)) {
        mesg = make_exception(1, &mesg, FALSE);
    }
    rb_longjmp(GET_EC(), tag, mesg, cause);
}

/**
 * Raises an exception in the current thread.
 * @param[in] mesg an Exception class or an `Exception` object.
 * @exception always raises an instance of the given exception class or
 *   the given `Exception` object.
 * @ingroup exception
 */
void
rb_exc_raise(VALUE mesg)
{
    rb_exc_exception(mesg, TAG_RAISE, Qundef);
}

/*!
 * Raises a fatal error in the current thread.
 *
 * Same as rb_exc_raise() but raises a fatal error, which Ruby codes
 * cannot rescue.
 * \ingroup exception
 */
void
rb_exc_fatal(VALUE mesg)
{
    rb_exc_exception(mesg, TAG_FATAL, Qnil);
}

void
rb_interrupt(void)
{
    rb_exc_raise(rb_exc_new(rb_eInterrupt, 0, 0));
}

enum {raise_opt_cause, raise_max_opt}; /*< \private */

static int
extract_raise_opts(int argc, VALUE *argv, VALUE *opts)
{
    int i;
    if (argc > 0) {
        VALUE opt;
        argc = rb_scan_args(argc, argv, "*:", NULL, &opt);
        if (!NIL_P(opt)) {
            if (!RHASH_EMPTY_P(opt)) {
                ID keywords[1];
                CONST_ID(keywords[0], "cause");
                rb_get_kwargs(opt, keywords, 0, -1-raise_max_opt, opts);
                if (!RHASH_EMPTY_P(opt)) argv[argc++] = opt;
                return argc;
            }
        }
    }
    for (i = 0; i < raise_max_opt; ++i) {
        opts[i] = Qundef;
    }
    return argc;
}

VALUE
rb_f_raise(int argc, VALUE *argv)
{
    VALUE err;
    VALUE opts[raise_max_opt], *const cause = &opts[raise_opt_cause];

    argc = extract_raise_opts(argc, argv, opts);
    if (argc == 0) {
        if (!UNDEF_P(*cause)) {
            rb_raise(rb_eArgError, "only cause is given with no arguments");
        }
        err = get_errinfo();
        if (!NIL_P(err)) {
            argc = 1;
            argv = &err;
        }
    }
    rb_raise_jump(rb_make_exception(argc, argv), *cause);

    UNREACHABLE_RETURN(Qnil);
}

/*
 *  call-seq:
 *    raise(exception, message = exception.to_s, backtrace = nil, cause: $!)
 *    raise(message = nil, cause: $!)
 *
 *  Raises an exception;
 *  see {Exceptions}[rdoc-ref:exceptions.md].
 *
 *  Argument +exception+ sets the class of the new exception;
 *  it should be class Exception or one of its subclasses
 *  (most commonly, RuntimeError or StandardError),
 *  or an instance of one of those classes:
 *
 *    begin
 *      raise(StandardError)
 *    rescue => x
 *      p x.class
 *    end
 *    # => StandardError
 *
 *  Argument +message+ sets the stored message in the new exception,
 *  which may be retrieved by method Exception#message;
 *  the message must be
 *  a {string-convertible object}[rdoc-ref:implicit_conversion.rdoc@String-Convertible+Objects]
 *  or +nil+:
 *
 *    begin
 *      raise(StandardError, 'Boom')
 *    rescue => x
 *      p x.message
 *    end
 *    # => "Boom"
 *
 *  If argument +message+ is not given,
 *  the message is the exception class name.
 *
 *  See {Messages}[rdoc-ref:exceptions.md@Messages].
 *
 *  Argument +backtrace+ might be used to modify the backtrace of the new exception,
 *  as reported by Exception#backtrace and Exception#backtrace_locations;
 *  the backtrace must be an array of Thread::Backtrace::Location, an array of
 *  strings, a single string, or +nil+.
 *
 *  Using the array of Thread::Backtrace::Location instances is the most consistent option
 *  and should be preferred when possible. The necessary value might be obtained
 *  from #caller_locations, or copied from Exception#backtrace_locations of another
 *  error:
 *
 *    begin
 *      do_some_work()
 *    rescue ZeroDivisionError => ex
 *      raise(LogicalError, "You have an error in your math", ex.backtrace_locations)
 *    end
 *
 *  The ways, both Exception#backtrace and Exception#backtrace_locations of the
 *  raised error are set to the same backtrace.
 *
 *  When the desired stack of locations is not available and should
 *  be constructed from scratch, an array of strings or a singular
 *  string can be used. In this case, only Exception#backtrace is set:
 *
 *    begin
 *      raise(StandardError, 'Boom', %w[dsl.rb:3 framework.rb:1])
 *    rescue => ex
 *      p ex.backtrace
 *      # => ["dsl.rb:3", "framework.rb:1"]
 *      p ex.backtrace_locations
 *      # => nil
 *    end
 *
 *  If argument +backtrace+ is not given,
 *  the backtrace is set according to an array of Thread::Backtrace::Location objects,
 *  as derived from the call stack.
 *
 *  See {Backtraces}[rdoc-ref:exceptions.md@Backtraces].
 *
 *  Keyword argument +cause+ sets the stored cause in the new exception,
 *  which may be retrieved by method Exception#cause;
 *  the cause must be an exception object (Exception or one of its subclasses),
 *  or +nil+:
 *
 *    begin
 *      raise(StandardError, cause: RuntimeError.new)
 *    rescue => x
 *      p x.cause
 *    end
 *    # => #<RuntimeError: RuntimeError>
 *
 *  If keyword argument +cause+ is not given,
 *  the cause is the value of <tt>$!</tt>.
 *
 *  See {Cause}[rdoc-ref:exceptions.md@Cause].
 *
 *  In the alternate calling sequence,
 *  where argument +exception+ _not_ given,
 *  raises a new exception of the class given by <tt>$!</tt>,
 *  or of class RuntimeError if <tt>$!</tt> is +nil+:
 *
 *    begin
 *      raise
 *    rescue => x
 *      p x
 *    end
 *    # => RuntimeError
 *
 *  With argument +exception+ not given,
 *  argument +message+ and keyword argument +cause+ may be given,
 *  but argument +backtrace+ may not be given.
 */

static VALUE
f_raise(int c, VALUE *v, VALUE _)
{
    return rb_f_raise(c, v);
}

static VALUE
make_exception(int argc, const VALUE *argv, int isstr)
{
    VALUE mesg, exc;

    mesg = Qnil;
    switch (argc) {
      case 0:
        return Qnil;
      case 1:
        exc = argv[0];
        if (isstr &&! NIL_P(exc)) {
            mesg = rb_check_string_type(exc);
            if (!NIL_P(mesg)) {
                return rb_exc_new3(rb_eRuntimeError, mesg);
            }
        }

      case 2:
      case 3:
        break;
      default:
        rb_error_arity(argc, 0, 3);
    }
    if (NIL_P(mesg)) {
        mesg = rb_check_funcall(argv[0], idException, argc != 1, &argv[1]);
    }
    if (UNDEF_P(mesg)) {
        rb_raise(rb_eTypeError, "exception class/object expected");
    }
    if (!rb_obj_is_kind_of(mesg, rb_eException)) {
        rb_raise(rb_eTypeError, "exception object expected");
    }
    if (argc == 3) {
        set_backtrace(mesg, argv[2]);
    }

    return mesg;
}

VALUE
rb_make_exception(int argc, const VALUE *argv)
{
    return make_exception(argc, argv, TRUE);
}

/*! \private
 */
static void
rb_raise_jump(VALUE mesg, VALUE cause)
{
    rb_execution_context_t *ec = GET_EC();
    const rb_control_frame_t *cfp = ec->cfp;
    const rb_callable_method_entry_t *me = rb_vm_frame_method_entry(cfp);
    VALUE klass = me->owner;
    VALUE self = cfp->self;
    ID mid = me->called_id;

    rb_vm_pop_frame(ec);
    EXEC_EVENT_HOOK(ec, RUBY_EVENT_C_RETURN, self, me->def->original_id, mid, klass, Qnil);

    rb_longjmp(ec, TAG_RAISE, mesg, cause);
}

void
rb_jump_tag(int tag)
{
    if (UNLIKELY(tag < TAG_RETURN || tag > TAG_FATAL)) {
        unknown_longjmp_status(tag);
    }
    EC_JUMP_TAG(GET_EC(), tag);
}

int
rb_block_given_p(void)
{
    if (rb_vm_frame_block_handler(GET_EC()->cfp) == VM_BLOCK_HANDLER_NONE) {
        return FALSE;
    }
    else {
        return TRUE;
    }
}

int rb_vm_cframe_keyword_p(const rb_control_frame_t *cfp);

int
rb_keyword_given_p(void)
{
    return rb_vm_cframe_keyword_p(GET_EC()->cfp);
}

VALUE rb_eThreadError;

void
rb_need_block(void)
{
    if (!rb_block_given_p()) {
        rb_vm_localjump_error("no block given", Qnil, 0);
    }
}

VALUE
rb_rescue2(VALUE (* b_proc) (VALUE), VALUE data1,
           VALUE (* r_proc) (VALUE, VALUE), VALUE data2, ...)
{
    va_list ap;
    va_start(ap, data2);
    VALUE ret = rb_vrescue2(b_proc, data1, r_proc, data2, ap);
    va_end(ap);
    return ret;
}

VALUE
rb_vrescue2(VALUE (* b_proc) (VALUE), VALUE data1,
            VALUE (* r_proc) (VALUE, VALUE), VALUE data2,
            va_list args)
{
    enum ruby_tag_type state;
    rb_execution_context_t * volatile ec = GET_EC();
    rb_control_frame_t *volatile cfp = ec->cfp;
    volatile VALUE result = Qfalse;
    volatile VALUE e_info = ec->errinfo;

    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
      retry_entry:
        result = (*b_proc) (data1);
    }
    else if (result) {
        /* escape from r_proc */
        if (state == TAG_RETRY) {
            state = TAG_NONE;
            ec->errinfo = Qnil;
            result = Qfalse;
            goto retry_entry;
        }
    }
    else {
        rb_vm_rewind_cfp(ec, cfp);

        if (state == TAG_RAISE) {
            int handle = FALSE;
            VALUE eclass;
            va_list ap;

            result = Qnil;
            /* reuses args when raised again after retrying in r_proc */
            va_copy(ap, args);
            while ((eclass = va_arg(ap, VALUE)) != 0) {
                if (rb_obj_is_kind_of(ec->errinfo, eclass)) {
                    handle = TRUE;
                    break;
                }
            }
            va_end(ap);

            if (handle) {
                state = TAG_NONE;
                if (r_proc) {
                    result = (*r_proc) (data2, ec->errinfo);
                }
                ec->errinfo = e_info;
            }
        }
    }
    EC_POP_TAG();
    if (state)
        EC_JUMP_TAG(ec, state);

    return result;
}

VALUE
rb_rescue(VALUE (* b_proc)(VALUE), VALUE data1,
          VALUE (* r_proc)(VALUE, VALUE), VALUE data2)
{
    return rb_rescue2(b_proc, data1, r_proc, data2, rb_eStandardError,
                      (VALUE)0);
}

VALUE
rb_protect(VALUE (* proc) (VALUE), VALUE data, int *pstate)
{
    volatile VALUE result = Qnil;
    volatile enum ruby_tag_type state;
    rb_execution_context_t * volatile ec = GET_EC();
    rb_control_frame_t *volatile cfp = ec->cfp;

    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        result = (*proc)(data);
    }
    else {
        rb_vm_rewind_cfp(ec, cfp);
    }
    EC_POP_TAG();

    if (pstate != NULL) *pstate = state;
    return result;
}

VALUE
rb_ensure(VALUE (*b_proc)(VALUE), VALUE data1, VALUE (*e_proc)(VALUE), VALUE data2)
{
    enum ruby_tag_type state;
    volatile VALUE result = Qnil;
    VALUE errinfo;
    rb_execution_context_t * volatile ec = GET_EC();
    EC_PUSH_TAG(ec);
    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
        result = (*b_proc) (data1);
    }
    EC_POP_TAG();
    errinfo = ec->errinfo;
    if (!NIL_P(errinfo) && !RB_TYPE_P(errinfo, T_OBJECT)) {
        ec->errinfo = Qnil;
    }
    (*e_proc)(data2);
    ec->errinfo = errinfo;
    if (state)
        EC_JUMP_TAG(ec, state);
    return result;
}

static ID
frame_func_id(const rb_control_frame_t *cfp)
{
    const rb_callable_method_entry_t *me = rb_vm_frame_method_entry(cfp);

    if (me) {
        return me->def->original_id;
    }
    else {
        return 0;
    }
}

static ID
frame_called_id(rb_control_frame_t *cfp)
{
    const rb_callable_method_entry_t *me = rb_vm_frame_method_entry(cfp);

    if (me) {
        return me->called_id;
    }
    else {
        return 0;
    }
}

ID
rb_frame_this_func(void)
{
    return frame_func_id(GET_EC()->cfp);
}

ID
rb_frame_callee(void)
{
    return frame_called_id(GET_EC()->cfp);
}

static rb_control_frame_t *
previous_frame(const rb_execution_context_t *ec)
{
    rb_control_frame_t *prev_cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(ec->cfp);
    /* check if prev_cfp can be accessible */
    if ((void *)(ec->vm_stack + ec->vm_stack_size) == (void *)(prev_cfp)) {
        return 0;
    }
    return prev_cfp;
}

static ID
prev_frame_callee(void)
{
    rb_control_frame_t *prev_cfp = previous_frame(GET_EC());
    if (!prev_cfp) return 0;
    return frame_called_id(prev_cfp);
}

static ID
prev_frame_func(void)
{
    rb_control_frame_t *prev_cfp = previous_frame(GET_EC());
    if (!prev_cfp) return 0;
    return frame_func_id(prev_cfp);
}

/*!
 * \private
 * Returns the ID of the last method in the call stack.
 * \sa rb_frame_this_func
 * \ingroup defmethod
 */
ID
rb_frame_last_func(void)
{
    const rb_execution_context_t *ec = GET_EC();
    const rb_control_frame_t *cfp = ec->cfp;
    ID mid;

    while (!(mid = frame_func_id(cfp)) &&
           (cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp),
            !RUBY_VM_CONTROL_FRAME_STACK_OVERFLOW_P(ec, cfp)));
    return mid;
}

/*
 *  call-seq:
 *     append_features(mod)   -> mod
 *
 *  When this module is included in another, Ruby calls
 *  #append_features in this module, passing it the receiving module
 *  in _mod_. Ruby's default implementation is to add the constants,
 *  methods, and module variables of this module to _mod_ if this
 *  module has not already been added to _mod_ or one of its
 *  ancestors. See also Module#include.
 */

static VALUE
rb_mod_append_features(VALUE module, VALUE include)
{
    if (!CLASS_OR_MODULE_P(include)) {
        Check_Type(include, T_CLASS);
    }
    rb_include_module(include, module);

    return module;
}

/*
 *  call-seq:
 *     include(module, ...)    -> self
 *
 *  Invokes Module.append_features on each parameter in reverse order.
 */

static VALUE
rb_mod_include(int argc, VALUE *argv, VALUE module)
{
    int i;
    ID id_append_features, id_included;

    CONST_ID(id_append_features, "append_features");
    CONST_ID(id_included, "included");

    if (BUILTIN_TYPE(module) == T_MODULE && FL_TEST(module, RMODULE_IS_REFINEMENT)) {
        rb_raise(rb_eTypeError, "Refinement#include has been removed");
    }

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i = 0; i < argc; i++) {
        Check_Type(argv[i], T_MODULE);
        if (FL_TEST(argv[i], RMODULE_IS_REFINEMENT)) {
            rb_raise(rb_eTypeError, "Cannot include refinement");
        }
    }
    while (argc--) {
        rb_funcall(argv[argc], id_append_features, 1, module);
        rb_funcall(argv[argc], id_included, 1, module);
    }
    return module;
}

/*
 *  call-seq:
 *     prepend_features(mod)   -> mod
 *
 *  When this module is prepended in another, Ruby calls
 *  #prepend_features in this module, passing it the receiving module
 *  in _mod_. Ruby's default implementation is to overlay the
 *  constants, methods, and module variables of this module to _mod_
 *  if this module has not already been added to _mod_ or one of its
 *  ancestors. See also Module#prepend.
 */

static VALUE
rb_mod_prepend_features(VALUE module, VALUE prepend)
{
    if (!CLASS_OR_MODULE_P(prepend)) {
        Check_Type(prepend, T_CLASS);
    }
    rb_prepend_module(prepend, module);

    return module;
}

/*
 *  call-seq:
 *     prepend(module, ...)    -> self
 *
 *  Invokes Module.prepend_features on each parameter in reverse order.
 */

static VALUE
rb_mod_prepend(int argc, VALUE *argv, VALUE module)
{
    int i;
    ID id_prepend_features, id_prepended;

    if (BUILTIN_TYPE(module) == T_MODULE && FL_TEST(module, RMODULE_IS_REFINEMENT)) {
        rb_raise(rb_eTypeError, "Refinement#prepend has been removed");
    }

    CONST_ID(id_prepend_features, "prepend_features");
    CONST_ID(id_prepended, "prepended");

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i = 0; i < argc; i++) {
        Check_Type(argv[i], T_MODULE);
        if (FL_TEST(argv[i], RMODULE_IS_REFINEMENT)) {
            rb_raise(rb_eTypeError, "Cannot prepend refinement");
        }
    }
    while (argc--) {
        rb_funcall(argv[argc], id_prepend_features, 1, module);
        rb_funcall(argv[argc], id_prepended, 1, module);
    }
    return module;
}

static void
ensure_class_or_module(VALUE obj)
{
    if (!RB_TYPE_P(obj, T_CLASS) && !RB_TYPE_P(obj, T_MODULE)) {
        rb_raise(rb_eTypeError,
                 "wrong argument type %"PRIsVALUE" (expected Class or Module)",
                 rb_obj_class(obj));
    }
}

static VALUE
hidden_identity_hash_new(void)
{
    VALUE hash = rb_ident_hash_new();

    RBASIC_CLEAR_CLASS(hash); /* hide from ObjectSpace */
    return hash;
}

static VALUE
refinement_superclass(VALUE superclass)
{
    if (RB_TYPE_P(superclass, T_MODULE)) {
        /* FIXME: Should ancestors of superclass be used here? */
        return rb_include_class_new(RCLASS_ORIGIN(superclass), rb_cBasicObject);
    }
    else {
        return superclass;
    }
}

/*!
 * \private
 */
static void
rb_using_refinement(rb_cref_t *cref, VALUE klass, VALUE module)
{
    VALUE iclass, c, superclass = klass;

    ensure_class_or_module(klass);
    Check_Type(module, T_MODULE);
    if (NIL_P(CREF_REFINEMENTS(cref))) {
        CREF_REFINEMENTS_SET(cref, hidden_identity_hash_new());
    }
    else {
        if (CREF_OMOD_SHARED(cref)) {
            CREF_REFINEMENTS_SET(cref, rb_hash_dup(CREF_REFINEMENTS(cref)));
            CREF_OMOD_SHARED_UNSET(cref);
        }
        if (!NIL_P(c = rb_hash_lookup(CREF_REFINEMENTS(cref), klass))) {
            superclass = c;
            while (c && RB_TYPE_P(c, T_ICLASS)) {
                if (RBASIC(c)->klass == module) {
                    /* already used refinement */
                    return;
                }
                c = RCLASS_SUPER(c);
            }
        }
    }
    superclass = refinement_superclass(superclass);
    c = iclass = rb_include_class_new(module, superclass);
    RB_OBJ_WRITE(c, &RCLASS_REFINED_CLASS(c), klass);

    RCLASS_M_TBL(c) = RCLASS_M_TBL(module);

    rb_hash_aset(CREF_REFINEMENTS(cref), klass, iclass);
}

static int
using_refinement(VALUE klass, VALUE module, VALUE arg)
{
    rb_cref_t *cref = (rb_cref_t *) arg;

    rb_using_refinement(cref, klass, module);
    return ST_CONTINUE;
}

static void
using_module_recursive(const rb_cref_t *cref, VALUE klass)
{
    ID id_refinements;
    VALUE super, module, refinements;

    super = RCLASS_SUPER(klass);
    if (super) {
        using_module_recursive(cref, super);
    }
    switch (BUILTIN_TYPE(klass)) {
      case T_MODULE:
        module = klass;
        break;

      case T_ICLASS:
        module = RBASIC(klass)->klass;
        break;

      default:
        rb_raise(rb_eTypeError, "wrong argument type %s (expected Module)",
                 rb_obj_classname(klass));
        break;
    }
    CONST_ID(id_refinements, "__refinements__");
    refinements = rb_attr_get(module, id_refinements);
    if (NIL_P(refinements)) return;
    rb_hash_foreach(refinements, using_refinement, (VALUE) cref);
}

/*!
 * \private
 */
static void
rb_using_module(const rb_cref_t *cref, VALUE module)
{
    Check_Type(module, T_MODULE);
    using_module_recursive(cref, module);
    rb_clear_all_refinement_method_cache();
}

/*
 *  call-seq:
 *     target    -> class_or_module
 *
 *  Return the class or module refined by the receiver.
 *
 *     module M
 *       refine String do
 *       end
 *     end
 *
 *     M.refinements[0].target # => String
 */
VALUE
rb_refinement_module_get_refined_class(VALUE module)
{
    ID id_refined_class;

    CONST_ID(id_refined_class, "__refined_class__");
    return rb_attr_get(module, id_refined_class);
}

static void
add_activated_refinement(VALUE activated_refinements,
                         VALUE klass, VALUE refinement)
{
    VALUE iclass, c, superclass = klass;

    if (!NIL_P(c = rb_hash_lookup(activated_refinements, klass))) {
        superclass = c;
        while (c && RB_TYPE_P(c, T_ICLASS)) {
            if (RBASIC(c)->klass == refinement) {
                /* already used refinement */
                return;
            }
            c = RCLASS_SUPER(c);
        }
    }
    superclass = refinement_superclass(superclass);
    c = iclass = rb_include_class_new(refinement, superclass);
    RB_OBJ_WRITE(c, &RCLASS_REFINED_CLASS(c), klass);
    refinement = RCLASS_SUPER(refinement);
    while (refinement && refinement != klass) {
        c = RCLASS_SET_SUPER(c, rb_include_class_new(refinement, RCLASS_SUPER(c)));
        RB_OBJ_WRITE(c, &RCLASS_REFINED_CLASS(c), klass);
        refinement = RCLASS_SUPER(refinement);
    }
    rb_hash_aset(activated_refinements, klass, iclass);
}

/*
 *  call-seq:
 *     refine(mod) { block }   -> module
 *
 *  Refine <i>mod</i> in the receiver.
 *
 *  Returns a module, where refined methods are defined.
 */

static VALUE
rb_mod_refine(VALUE module, VALUE klass)
{
    VALUE refinement;
    ID id_refinements, id_activated_refinements,
       id_refined_class, id_defined_at;
    VALUE refinements, activated_refinements;
    rb_thread_t *th = GET_THREAD();
    VALUE block_handler = rb_vm_frame_block_handler(th->ec->cfp);

    if (block_handler == VM_BLOCK_HANDLER_NONE) {
        rb_raise(rb_eArgError, "no block given");
    }
    if (vm_block_handler_type(block_handler) != block_handler_type_iseq) {
        rb_raise(rb_eArgError, "can't pass a Proc as a block to Module#refine");
    }

    ensure_class_or_module(klass);
    CONST_ID(id_refinements, "__refinements__");
    refinements = rb_attr_get(module, id_refinements);
    if (NIL_P(refinements)) {
        refinements = hidden_identity_hash_new();
        rb_ivar_set(module, id_refinements, refinements);
    }
    CONST_ID(id_activated_refinements, "__activated_refinements__");
    activated_refinements = rb_attr_get(module, id_activated_refinements);
    if (NIL_P(activated_refinements)) {
        activated_refinements = hidden_identity_hash_new();
        rb_ivar_set(module, id_activated_refinements,
                    activated_refinements);
    }
    refinement = rb_hash_lookup(refinements, klass);
    if (NIL_P(refinement)) {
        VALUE superclass = refinement_superclass(klass);
        refinement = rb_refinement_new();
        RCLASS_SET_SUPER(refinement, superclass);
        RUBY_ASSERT(BUILTIN_TYPE(refinement) == T_MODULE);
        FL_SET(refinement, RMODULE_IS_REFINEMENT);
        CONST_ID(id_refined_class, "__refined_class__");
        rb_ivar_set(refinement, id_refined_class, klass);
        CONST_ID(id_defined_at, "__defined_at__");
        rb_ivar_set(refinement, id_defined_at, module);
        rb_hash_aset(refinements, klass, refinement);
        add_activated_refinement(activated_refinements, klass, refinement);
    }
    rb_yield_refine_block(refinement, activated_refinements);
    return refinement;
}

static void
ignored_block(VALUE module, const char *klass)
{
    const char *anon = "";
    Check_Type(module, T_MODULE);
    if (!RTEST(rb_search_class_path(module))) {
        anon = ", maybe for Module.new";
    }
    rb_warn("%s""using doesn't call the given block""%s.", klass, anon);
}

/*
 *  call-seq:
 *     using(module)    -> self
 *
 *  Import class refinements from <i>module</i> into the current class or
 *  module definition.
 */

static VALUE
mod_using(VALUE self, VALUE module)
{
    rb_control_frame_t *prev_cfp = previous_frame(GET_EC());

    if (prev_frame_func()) {
        rb_raise(rb_eRuntimeError,
                 "Module#using is not permitted in methods");
    }
    if (prev_cfp && prev_cfp->self != self) {
        rb_raise(rb_eRuntimeError, "Module#using is not called on self");
    }
    if (rb_block_given_p()) {
        ignored_block(module, "Module#");
    }
    rb_using_module(rb_vm_cref_replace_with_duplicated_cref(), module);
    return self;
}


/*
 *  call-seq:
 *     refinements -> array
 *
 *  Returns an array of +Refinement+ defined within the receiver.
 *
 *     module A
 *       refine Integer do
 *       end
 *
 *       refine String do
 *       end
 *     end
 *
 *     p A.refinements
 *
 *  <em>produces:</em>
 *
 *     [#<refinement:Integer@A>, #<refinement:String@A>]
 */
static VALUE
mod_refinements(VALUE self)
{
    ID id_refinements;
    VALUE refinements;

    CONST_ID(id_refinements, "__refinements__");
    refinements = rb_attr_get(self, id_refinements);
    if (NIL_P(refinements)) {
        return rb_ary_new();
    }
    return rb_hash_values(refinements);
}

static int
used_modules_i(VALUE _, VALUE mod, VALUE ary)
{
    ID id_defined_at;
    CONST_ID(id_defined_at, "__defined_at__");
    while (BUILTIN_TYPE(rb_class_of(mod)) == T_MODULE && FL_TEST(rb_class_of(mod), RMODULE_IS_REFINEMENT)) {
        rb_ary_push(ary, rb_attr_get(rb_class_of(mod), id_defined_at));
        mod = RCLASS_SUPER(mod);
    }
    return ST_CONTINUE;
}

/*
 *  call-seq:
 *     used_modules -> array
 *
 *  Returns an array of all modules used in the current scope. The ordering
 *  of modules in the resulting array is not defined.
 *
 *     module A
 *       refine Object do
 *       end
 *     end
 *
 *     module B
 *       refine Object do
 *       end
 *     end
 *
 *     using A
 *     using B
 *     p Module.used_modules
 *
 *  <em>produces:</em>
 *
 *     [B, A]
 */
static VALUE
rb_mod_s_used_modules(VALUE _)
{
    const rb_cref_t *cref = rb_vm_cref();
    VALUE ary = rb_ary_new();

    while (cref) {
        if (!NIL_P(CREF_REFINEMENTS(cref))) {
            rb_hash_foreach(CREF_REFINEMENTS(cref), used_modules_i, ary);
        }
        cref = CREF_NEXT(cref);
    }

    return rb_funcall(ary, rb_intern("uniq"), 0);
}

static int
used_refinements_i(VALUE _, VALUE mod, VALUE ary)
{
    while (BUILTIN_TYPE(rb_class_of(mod)) == T_MODULE && FL_TEST(rb_class_of(mod), RMODULE_IS_REFINEMENT)) {
        rb_ary_push(ary, rb_class_of(mod));
        mod = RCLASS_SUPER(mod);
    }
    return ST_CONTINUE;
}

/*
 *  call-seq:
 *     used_refinements -> array
 *
 *  Returns an array of all modules used in the current scope. The ordering
 *  of modules in the resulting array is not defined.
 *
 *     module A
 *       refine Object do
 *       end
 *     end
 *
 *     module B
 *       refine Object do
 *       end
 *     end
 *
 *     using A
 *     using B
 *     p Module.used_refinements
 *
 *  <em>produces:</em>
 *
 *     [#<refinement:Object@B>, #<refinement:Object@A>]
 */
static VALUE
rb_mod_s_used_refinements(VALUE _)
{
    const rb_cref_t *cref = rb_vm_cref();
    VALUE ary = rb_ary_new();

    while (cref) {
        if (!NIL_P(CREF_REFINEMENTS(cref))) {
            rb_hash_foreach(CREF_REFINEMENTS(cref), used_refinements_i, ary);
        }
        cref = CREF_NEXT(cref);
    }

    return ary;
}

struct refinement_import_methods_arg {
    rb_cref_t *cref;
    VALUE refinement;
    VALUE module;
};

/* vm.c */
rb_cref_t *rb_vm_cref_dup_without_refinements(const rb_cref_t *cref);

static enum rb_id_table_iterator_result
refinement_import_methods_i(ID key, VALUE value, void *data)
{
    const rb_method_entry_t *me = (const rb_method_entry_t *)value;
    struct refinement_import_methods_arg *arg = (struct refinement_import_methods_arg *)data;

    if (me->def->type != VM_METHOD_TYPE_ISEQ) {
        rb_raise(rb_eArgError, "Can't import method which is not defined with Ruby code: %"PRIsVALUE"#%"PRIsVALUE, rb_class_path(arg->module), rb_id2str(key));
    }
    rb_cref_t *new_cref = rb_vm_cref_dup_without_refinements(me->def->body.iseq.cref);
    CREF_REFINEMENTS_SET(new_cref, CREF_REFINEMENTS(arg->cref));
    rb_add_method_iseq(arg->refinement, key, me->def->body.iseq.iseqptr, new_cref, METHOD_ENTRY_VISI(me));
    return ID_TABLE_CONTINUE;
}

/*
 * Note: docs for the method are in class.c
 */

static VALUE
refinement_import_methods(int argc, VALUE *argv, VALUE refinement)
{
    int i;
    struct refinement_import_methods_arg arg;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i = 0; i < argc; i++) {
        Check_Type(argv[i], T_MODULE);
        if (RCLASS_SUPER(argv[i])) {
            rb_warn("%"PRIsVALUE" has ancestors, but Refinement#import_methods doesn't import their methods", rb_class_path(argv[i]));
        }
    }
    arg.cref = rb_vm_cref_replace_with_duplicated_cref();
    arg.refinement = refinement;
    for (i = 0; i < argc; i++) {
        arg.module = argv[i];
        struct rb_id_table *m_tbl = RCLASS_M_TBL(argv[i]);
        if (!m_tbl) continue;
        rb_id_table_foreach(m_tbl, refinement_import_methods_i, &arg);
    }
    return refinement;
}

void
rb_obj_call_init(VALUE obj, int argc, const VALUE *argv)
{
    rb_obj_call_init_kw(obj, argc, argv, RB_NO_KEYWORDS);
}

void
rb_obj_call_init_kw(VALUE obj, int argc, const VALUE *argv, int kw_splat)
{
    PASS_PASSED_BLOCK_HANDLER();
    rb_funcallv_kw(obj, idInitialize, argc, argv, kw_splat);
}

void
rb_extend_object(VALUE obj, VALUE module)
{
    rb_include_module(rb_singleton_class(obj), module);
}

/*
 *  call-seq:
 *     extend_object(obj)    -> obj
 *
 *  Extends the specified object by adding this module's constants and
 *  methods (which are added as singleton methods). This is the callback
 *  method used by Object#extend.
 *
 *     module Picky
 *       def Picky.extend_object(o)
 *         if String === o
 *           puts "Can't add Picky to a String"
 *         else
 *           puts "Picky added to #{o.class}"
 *           super
 *         end
 *       end
 *     end
 *     (s = Array.new).extend Picky  # Call Object.extend
 *     (s = "quick brown fox").extend Picky
 *
 *  <em>produces:</em>
 *
 *     Picky added to Array
 *     Can't add Picky to a String
 */

static VALUE
rb_mod_extend_object(VALUE mod, VALUE obj)
{
    rb_extend_object(obj, mod);
    return obj;
}

/*
 *  call-seq:
 *     obj.extend(module, ...)    -> obj
 *
 *  Adds to _obj_ the instance methods from each module given as a
 *  parameter.
 *
 *     module Mod
 *       def hello
 *         "Hello from Mod.\n"
 *       end
 *     end
 *
 *     class Klass
 *       def hello
 *         "Hello from Klass.\n"
 *       end
 *     end
 *
 *     k = Klass.new
 *     k.hello         #=> "Hello from Klass.\n"
 *     k.extend(Mod)   #=> #<Klass:0x401b3bc8>
 *     k.hello         #=> "Hello from Mod.\n"
 */

static VALUE
rb_obj_extend(int argc, VALUE *argv, VALUE obj)
{
    int i;
    ID id_extend_object, id_extended;

    CONST_ID(id_extend_object, "extend_object");
    CONST_ID(id_extended, "extended");

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i = 0; i < argc; i++) {
        Check_Type(argv[i], T_MODULE);
        if (FL_TEST(argv[i], RMODULE_IS_REFINEMENT)) {
            rb_raise(rb_eTypeError, "Cannot extend object with refinement");
        }
    }
    while (argc--) {
        rb_funcall(argv[argc], id_extend_object, 1, obj);
        rb_funcall(argv[argc], id_extended, 1, obj);
    }
    return obj;
}

VALUE
rb_top_main_class(const char *method)
{
    VALUE klass = GET_THREAD()->top_wrapper;

    if (!klass) return rb_cObject;
    rb_warning("main.%s in the wrapped load is effective only in wrapper module", method);
    return klass;
}

/*
 *  call-seq:
 *     include(module, ...)   -> self
 *
 *  Invokes Module.append_features on each parameter in turn.
 *  Effectively adds the methods and constants in each module to the
 *  receiver.
 */

static VALUE
top_include(int argc, VALUE *argv, VALUE self)
{
    return rb_mod_include(argc, argv, rb_top_main_class("include"));
}

/*
 *  call-seq:
 *     using(module)    -> self
 *
 *  Import class refinements from <i>module</i> into the scope where
 *  #using is called.
 */

static VALUE
top_using(VALUE self, VALUE module)
{
    const rb_cref_t *cref = CREF_NEXT(rb_vm_cref());
    rb_control_frame_t *prev_cfp = previous_frame(GET_EC());
    rb_thread_t *th = GET_THREAD();

    if ((th->top_wrapper ? CREF_NEXT(cref) : cref) ||
        (prev_cfp && rb_vm_frame_method_entry(prev_cfp))) {
        rb_raise(rb_eRuntimeError, "main.using is permitted only at toplevel");
    }
    if (rb_block_given_p()) {
        ignored_block(module, "main.");
    }
    rb_using_module(rb_vm_cref_replace_with_duplicated_cref(), module);
    return self;
}

static const VALUE *
errinfo_place(const rb_execution_context_t *ec)
{
    const rb_control_frame_t *cfp = ec->cfp;
    const rb_control_frame_t *end_cfp = RUBY_VM_END_CONTROL_FRAME(ec);

    while (RUBY_VM_VALID_CONTROL_FRAME_P(cfp, end_cfp)) {
        if (VM_FRAME_RUBYFRAME_P(cfp)) {
            if (ISEQ_BODY(cfp->iseq)->type == ISEQ_TYPE_RESCUE) {
                return &cfp->ep[VM_ENV_INDEX_LAST_LVAR];
            }
            else if (ISEQ_BODY(cfp->iseq)->type == ISEQ_TYPE_ENSURE &&
                     !THROW_DATA_P(cfp->ep[VM_ENV_INDEX_LAST_LVAR]) &&
                     !FIXNUM_P(cfp->ep[VM_ENV_INDEX_LAST_LVAR])) {
                return &cfp->ep[VM_ENV_INDEX_LAST_LVAR];
            }
        }
        cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
    }
    return 0;
}

VALUE
rb_ec_get_errinfo(const rb_execution_context_t *ec)
{
    const VALUE *ptr = errinfo_place(ec);
    if (ptr) {
        return *ptr;
    }
    else {
        return ec->errinfo;
    }
}

static VALUE
get_errinfo(void)
{
    return get_ec_errinfo(GET_EC());
}

static VALUE
errinfo_getter(ID id, VALUE *_)
{
    return get_errinfo();
}

VALUE
rb_errinfo(void)
{
    return GET_EC()->errinfo;
}

void
rb_set_errinfo(VALUE err)
{
    if (!NIL_P(err) && !rb_obj_is_kind_of(err, rb_eException)) {
        rb_raise(rb_eTypeError, "assigning non-exception to $!");
    }
    GET_EC()->errinfo = err;
}

static VALUE
errat_getter(ID id, VALUE *_)
{
    VALUE err = get_errinfo();
    if (!NIL_P(err)) {
        return rb_get_backtrace(err);
    }
    else {
        return Qnil;
    }
}

static void
errat_setter(VALUE val, ID id, VALUE *var)
{
    VALUE err = get_errinfo();
    if (NIL_P(err)) {
        rb_raise(rb_eArgError, "$! not set");
    }
    set_backtrace(err, val);
}

/*
 *  call-seq:
 *     __method__         -> symbol
 *
 *  Returns the name at the definition of the current method as a
 *  Symbol.
 *  If called outside of a method, it returns <code>nil</code>.
 *
 */

static VALUE
rb_f_method_name(VALUE _)
{
    ID fname = prev_frame_func(); /* need *method* ID */

    if (fname) {
        return ID2SYM(fname);
    }
    else {
        return Qnil;
    }
}

/*
 *  call-seq:
 *     __callee__         -> symbol
 *
 *  Returns the called name of the current method as a Symbol.
 *  If called outside of a method, it returns <code>nil</code>.
 *
 */

static VALUE
rb_f_callee_name(VALUE _)
{
    ID fname = prev_frame_callee(); /* need *callee* ID */

    if (fname) {
        return ID2SYM(fname);
    }
    else {
        return Qnil;
    }
}

/*
 *  call-seq:
 *     __dir__         -> string
 *
 *  Returns the canonicalized absolute path of the directory of the file from
 *  which this method is called. It means symlinks in the path is resolved.
 *  If <code>__FILE__</code> is <code>nil</code>, it returns <code>nil</code>.
 *  The return value equals to <code>File.dirname(File.realpath(__FILE__))</code>.
 *
 */
static VALUE
f_current_dirname(VALUE _)
{
    VALUE base = rb_current_realfilepath();
    if (NIL_P(base)) {
        return Qnil;
    }
    base = rb_file_dirname(base);
    return base;
}

/*
 *  call-seq:
 *     global_variables    -> array
 *
 *  Returns an array of the names of global variables. This includes
 *  special regexp global variables such as <tt>$~</tt> and <tt>$+</tt>,
 *  but does not include the numbered regexp global variables (<tt>$1</tt>,
 *  <tt>$2</tt>, etc.).
 *
 *     global_variables.grep /std/   #=> [:$stdin, :$stdout, :$stderr]
 */

static VALUE
f_global_variables(VALUE _)
{
    return rb_f_global_variables();
}

/*
 *  call-seq:
 *     trace_var(symbol, cmd )             -> nil
 *     trace_var(symbol) {|val| block }    -> nil
 *
 *  Controls tracing of assignments to global variables. The parameter
 *  +symbol+ identifies the variable (as either a string name or a
 *  symbol identifier). _cmd_ (which may be a string or a
 *  +Proc+ object) or block is executed whenever the variable
 *  is assigned. The block or +Proc+ object receives the
 *  variable's new value as a parameter. Also see
 *  #untrace_var.
 *
 *     trace_var :$_, proc {|v| puts "$_ is now '#{v}'" }
 *     $_ = "hello"
 *     $_ = ' there'
 *
 *  <em>produces:</em>
 *
 *     $_ is now 'hello'
 *     $_ is now ' there'
 */

static VALUE
f_trace_var(int c, const VALUE *a, VALUE _)
{
    return rb_f_trace_var(c, a);
}

/*
 *  call-seq:
 *     untrace_var(symbol [, cmd] )   -> array or nil
 *
 *  Removes tracing for the specified command on the given global
 *  variable and returns +nil+. If no command is specified,
 *  removes all tracing for that variable and returns an array
 *  containing the commands actually removed.
 */

static VALUE
f_untrace_var(int c, const VALUE *a, VALUE _)
{
    return rb_f_untrace_var(c, a);
}

void
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);

    rb_define_global_function("global_variables", f_global_variables, 0);

    rb_define_global_function("__method__", rb_f_method_name, 0);
    rb_define_global_function("__callee__", rb_f_callee_name, 0);
    rb_define_global_function("__dir__", f_current_dirname, 0);

    rb_define_method(rb_cModule, "include", rb_mod_include, -1);
    rb_define_method(rb_cModule, "prepend", rb_mod_prepend, -1);

    rb_define_private_method(rb_cModule, "append_features", rb_mod_append_features, 1);
    rb_define_private_method(rb_cModule, "extend_object", rb_mod_extend_object, 1);
    rb_define_private_method(rb_cModule, "prepend_features", rb_mod_prepend_features, 1);
    rb_define_private_method(rb_cModule, "refine", rb_mod_refine, 1);
    rb_define_private_method(rb_cModule, "using", mod_using, 1);
    rb_define_method(rb_cModule, "refinements", mod_refinements, 0);
    rb_define_singleton_method(rb_cModule, "used_modules",
                               rb_mod_s_used_modules, 0);
    rb_define_singleton_method(rb_cModule, "used_refinements",
                               rb_mod_s_used_refinements, 0);
    rb_undef_method(rb_cClass, "refine");
    rb_define_private_method(rb_cRefinement, "import_methods", refinement_import_methods, -1);
    rb_define_method(rb_cRefinement, "target", rb_refinement_module_get_refined_class, 0);
    rb_undef_method(rb_cRefinement, "append_features");
    rb_undef_method(rb_cRefinement, "prepend_features");
    rb_undef_method(rb_cRefinement, "extend_object");

    rb_undef_method(rb_cClass, "module_function");

    Init_vm_eval();
    Init_eval_method();

    rb_define_singleton_method(rb_cModule, "nesting", rb_mod_nesting, 0);
    rb_define_singleton_method(rb_cModule, "constants", rb_mod_s_constants, -1);

    rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
                             "include", top_include, -1);
    rb_define_private_method(rb_singleton_class(rb_vm_top_self()),
                             "using", top_using, 1);

    rb_define_method(rb_mKernel, "extend", rb_obj_extend, -1);

    rb_define_global_function("trace_var", f_trace_var, -1);
    rb_define_global_function("untrace_var", f_untrace_var, -1);

    rb_vm_register_special_exception(ruby_error_reenter, rb_eFatal, "exception reentered");
    rb_vm_register_special_exception(ruby_error_stackfatal, rb_eFatal, "machine stack overflow in critical region");

    id_signo = rb_intern_const("signo");
    id_status = rb_intern_const("status");
}

int
rb_errno(void)
{
    return *rb_orig_errno_ptr();
}

void
rb_errno_set(int e)
{
    *rb_orig_errno_ptr() = e;
}

int *
rb_errno_ptr(void)
{
    return rb_orig_errno_ptr();
}