Make rb_scan_args handle keywords more similar to Ruby methods (#2460)

Cfuncs that use rb_scan_args with the : entry suffer similar keyword
argument separation issues that Ruby methods suffer if the cfuncs
accept optional or variable arguments.

This makes the following changes to : handling.

* Treats as **kw, prompting keyword argument separation warnings
  if called with a positional hash.

* Do not look for an option hash if empty keywords are provided.
  For backwards compatibility, treat an empty keyword splat as a empty
  mandatory positional hash argument, but emit a a warning, as this
  behavior will be removed in Ruby 3.  The argument number check
  needs to be moved lower so it can correctly handle an empty
  positional argument being added.

* If the last argument is nil and it is necessary to treat it as an option
  hash in order to make sure all arguments are processed, continue to
  treat the last argument as the option hash. Emit a warning in this case,
  as this behavior will be removed in Ruby 3.

* If splitting the keyword hash into two hashes, issue a warning, as we
  will not be splitting hashes in Ruby 3.

* If the keyword argument is required to fill a mandatory positional
  argument, continue to do so, but emit a warning as this behavior will
  be going away in Ruby 3.

* If keyword arguments are provided and the last argument is not a hash,
  that indicates something wrong. This can happen if a cfunc is calling
  rb_scan_args multiple times, and providing arguments that were not
  passed to it from Ruby.  Callers need to switch to the new
  rb_scan_args_kw function, which allows passing of whether keywords
  were provided.

This commit fixes all warnings caused by the changes above.

It switches some function calls to *_kw versions with appropriate
kw_splat flags. If delegating arguments, RB_PASS_CALLED_KEYWORDS
is used.  If creating new arguments, RB_PASS_KEYWORDS is used if
the last argument is a hash to be treated as keywords.

In open_key_args in io.c, use rb_scan_args_kw.
In this case, the arguments provided come from another C
function, not Ruby.  The last argument may or may not be a hash,
so we can't set keyword argument mode.  However, if it is a
hash, we don't want to warn when treating it as keywords.

In Ruby files, make sure to appropriately use keyword splats
or literal keywords when calling Cfuncs that now issue keyword
argument separation warnings through rb_scan_args.  Also, make
sure not to pass nil in place of an option hash.

Work around Kernel#warn warnings due to problems in the Rubygems
override of the method.  There is an open pull request to fix
these issues in Rubygems, but part of the Rubygems tests for
their override fail on ruby-head due to rb_scan_args not
recognizing empty keyword splats, which this commit fixes.

Implementation wise, adding rb_scan_args_kw is kind of a pain,
because rb_scan_args takes a variable number of arguments.
In order to not duplicate all the code, the function internals need
to be split into two functions taking a va_list, and to avoid passing
in a ton of arguments, a single struct argument is used to handle
the variables previously local to the function.

class.c

@@ -1943,85 +1943,172 @@ rb_get_kwargs(VALUE keyword_hash, const ID *table, int required, int optional, V
 #undef extract_kwarg
 }
 
-#undef rb_scan_args
+struct rb_scan_args_t {
-int
+    int argc;
-rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
+    const VALUE *argv;
-{
-    int i;
-    const char *p = fmt;
-    VALUE *var;
     va_list vargs;
-    int f_var = 0, f_hash = 0, f_block = 0;
+    int f_var;
-    int n_lead = 0, n_opt = 0, n_trail = 0, n_mand;
+    int f_hash;
-    int argi = 0, last_idx = -1;
+    int f_block;
-    VALUE hash = Qnil, last_hash = 0;
+    int n_lead;
+    int n_opt;
+    int n_trail;
+    int n_mand;
+    int argi;
+    int last_idx;
+    VALUE hash;
+    VALUE last_hash;
+    VALUE *tmp_buffer;
+};
+
+static void
+rb_scan_args_parse(int kw_flag, int argc, const VALUE *argv, const char *fmt, struct rb_scan_args_t *arg)
+{
+    const char *p = fmt;
+    VALUE *tmp_buffer = arg->tmp_buffer;
+    int keyword_given = 0;
+    int empty_keyword_given = 0;
+    int last_hash_keyword = 0;
+
+    memset(arg, 0, sizeof(*arg));
+    arg->last_idx = -1;
+    arg->hash = Qnil;
+
+    switch(kw_flag) {
+      case RB_SCAN_ARGS_PASS_CALLED_KEYWORDS:
+        if(!(keyword_given = rb_keyword_given_p())) {
+            empty_keyword_given = rb_empty_keyword_given_p();
+        }
+        break;
+      case RB_SCAN_ARGS_KEYWORDS:
+        keyword_given = 1;
+        break;
+      case RB_SCAN_ARGS_EMPTY_KEYWORDS:
+        empty_keyword_given = 1;
+        break;
+      case RB_SCAN_ARGS_LAST_HASH_KEYWORDS:
+        last_hash_keyword = 1;
+        break;
+    }
 
     if (ISDIGIT(*p)) {
-	n_lead = *p - '0';
+        arg->n_lead = *p - '0';
 	p++;
 	if (ISDIGIT(*p)) {
-	    n_opt = *p - '0';
+            arg->n_opt = *p - '0';
 	    p++;
 	}
     }
     if (*p == '*') {
-	f_var = 1;
+        arg->f_var = 1;
 	p++;
     }
     if (ISDIGIT(*p)) {
-	n_trail = *p - '0';
+        arg->n_trail = *p - '0';
 	p++;
     }
     if (*p == ':') {
-	f_hash = 1;
+        arg->f_hash = 1;
 	p++;
     }
     if (*p == '&') {
-	f_block = 1;
+        arg->f_block = 1;
 	p++;
     }
     if (*p != '\0') {
 	rb_fatal("bad scan arg format: %s", fmt);
     }
-    n_mand = n_lead + n_trail;
+    arg->n_mand = arg->n_lead + arg->n_trail;
-
-    if (argc < n_mand)
-	goto argc_error;
-
-    va_start(vargs, fmt);
 
     /* capture an option hash - phase 1: pop */
-    if (f_hash && n_mand < argc) {
+    /* Ignore final positional hash if empty keywords given */
-	VALUE last = argv[argc - 1];
+    if (argc > 0 && !(arg->f_hash && empty_keyword_given)) {
+        VALUE last = argv[argc - 1];
 
-	if (NIL_P(last)) {
+        if (arg->f_hash && arg->n_mand < argc) {
-	    /* nil is taken as an empty option hash only if it is not
+            if (keyword_given) {
-	       ambiguous; i.e. '*' is not specified and arguments are
+                if (!RB_TYPE_P(last, T_HASH)) {
-	       given more than sufficient */
+                    rb_warn("Keyword flag set when calling rb_scan_args, but last entry is not a hash");
-	    if (!f_var && n_mand + n_opt < argc)
+                }
-		argc--;
+                else {
-	}
+                    arg->hash = last;
-	else {
+                }
-	    hash = rb_check_hash_type(last);
+            }
-	    if (!NIL_P(hash)) {
+            else if (NIL_P(last)) {
-		VALUE opts = rb_extract_keywords(&hash);
+                /* For backwards compatibility, nil is taken as an empty
-		if (!(last_hash = hash)) argc--;
+                   option hash only if it is not ambiguous; i.e. '*' is
-		else last_idx = argc - 1;
+                   not specified and arguments are given more than sufficient.
-		hash = opts ? opts : Qnil;
+                   This will be removed in Ruby 3. */
-	    }
+                if (!arg->f_var && arg->n_mand + arg->n_opt < argc) {
-	}
+                    rb_warn("The last argument is nil, treating as empty keywords");
+                    argc--;
+                }
+            }
+            else {
+                arg->hash = rb_check_hash_type(last);
+            }
+
+            /* Ruby 3: Remove if branch, as it will not attempt to split hashes */
+            if (!NIL_P(arg->hash)) {
+                VALUE opts = rb_extract_keywords(&arg->hash);
+
+                if (!(arg->last_hash = arg->hash)) {
+                    if (!keyword_given && !last_hash_keyword) {
+                        /* Warn if treating positional as keyword, as in Ruby 3,
+                           this will be an error */
+                        rb_warn("The last argument is used as the keyword parameter");
+                    }
+                    argc--;
+                }
+                else {
+                    /* Warn if splitting either positional hash to keywords or keywords
+                       to positional hash, as in Ruby 3, no splitting will be done */
+                    rb_warn("The last argument is split into positional and keyword parameters");
+                    arg->last_idx = argc - 1;
+                }
+                arg->hash = opts ? opts : Qnil;
+            }
+        }
+        else if (arg->f_hash && keyword_given && arg->n_mand == argc) {
+            /* Warn if treating keywords as positional, as in Ruby 3, this will be an error */
+            rb_warn("The keyword argument is passed as the last hash parameter");
+        }
     }
+    if (arg->f_hash && arg->n_mand == argc+1 && empty_keyword_given) {
+        VALUE *ptr = rb_alloc_tmp_buffer2(tmp_buffer, argc+1, sizeof(VALUE));
+        memcpy(ptr, argv, sizeof(VALUE)*argc);
+        ptr[argc] = rb_hash_new();
+        argc++;
+        *(&argv) = ptr;
+        rb_warn("The keyword argument is passed as the last hash parameter");
+    }
+
+    arg->argc = argc;
+    arg->argv = argv;
+}
+
+static int
+rb_scan_args_assign(struct rb_scan_args_t *arg, va_list vargs)
+{
+    int argi = 0;
+    int i;
+    VALUE *var;
+
+    if (arg->argc < arg->n_mand) {
+        return 1;
+    }
+
     /* capture leading mandatory arguments */
-    for (i = n_lead; i-- > 0; ) {
+    for (i = arg->n_lead; i-- > 0; ) {
 	var = va_arg(vargs, VALUE *);
-	if (var) *var = (argi == last_idx) ? last_hash : argv[argi];
+        if (var) *var = (argi == arg->last_idx) ? arg->last_hash : arg->argv[argi];
 	argi++;
     }
     /* capture optional arguments */
-    for (i = n_opt; i-- > 0; ) {
+    for (i = arg->n_opt; i-- > 0; ) {
 	var = va_arg(vargs, VALUE *);
-	if (argi < argc - n_trail) {
+        if (argi < arg->argc - arg->n_trail) {
-	    if (var) *var = (argi == last_idx) ? last_hash : argv[argi];
+            if (var) *var = (argi == arg->last_idx) ? arg->last_hash : arg->argv[argi];
 	    argi++;
 	}
 	else {
@@ -2029,15 +2116,15 @@ rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
 	}
     }
     /* capture variable length arguments */
-    if (f_var) {
+    if (arg->f_var) {
-	int n_var = argc - argi - n_trail;
+        int n_var = arg->argc - argi - arg->n_trail;
 
 	var = va_arg(vargs, VALUE *);
 	if (0 < n_var) {
 	    if (var) {
-		int f_last = (last_idx + 1 == argc - n_trail);
+                int f_last = (arg->last_idx + 1 == arg->argc - arg->n_trail);
-		*var = rb_ary_new4(n_var-f_last, &argv[argi]);
+                *var = rb_ary_new4(n_var - f_last, &arg->argv[argi]);
-		if (f_last) rb_ary_push(*var, last_hash);
+                if (f_last) rb_ary_push(*var, arg->last_hash);
 	    }
 	    argi += n_var;
 	}
@@ -2046,18 +2133,18 @@ rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
 	}
     }
     /* capture trailing mandatory arguments */
-    for (i = n_trail; i-- > 0; ) {
+    for (i = arg->n_trail; i-- > 0; ) {
 	var = va_arg(vargs, VALUE *);
-	if (var) *var = (argi == last_idx) ? last_hash : argv[argi];
+        if (var) *var = (argi == arg->last_idx) ? arg->last_hash : arg->argv[argi];
 	argi++;
     }
     /* capture an option hash - phase 2: assignment */
-    if (f_hash) {
+    if (arg->f_hash) {
 	var = va_arg(vargs, VALUE *);
-	if (var) *var = hash;
+        if (var) *var = arg->hash;
     }
     /* capture iterator block */
-    if (f_block) {
+    if (arg->f_block) {
 	var = va_arg(vargs, VALUE *);
 	if (rb_block_given_p()) {
 	    *var = rb_block_proc();
@@ -2066,14 +2153,53 @@ rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
 	    *var = Qnil;
 	}
     }
+
+    if (argi < arg->argc) return 1;
+
+    return 0;
+}
+
+#undef rb_scan_args
+int
+rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
+{
+    int error;
+    va_list vargs;
+    VALUE tmp_buffer = 0;
+    struct rb_scan_args_t arg;
+    arg.tmp_buffer = &tmp_buffer;
+    rb_scan_args_parse(RB_SCAN_ARGS_PASS_CALLED_KEYWORDS, argc, argv, fmt, &arg);
+    va_start(vargs,fmt);
+    error = rb_scan_args_assign(&arg, vargs);
     va_end(vargs);
-
+    if (tmp_buffer) {
-    if (argi < argc) {
+        rb_free_tmp_buffer(&tmp_buffer);
-      argc_error:
-	rb_error_arity(argc, n_mand, f_var ? UNLIMITED_ARGUMENTS : n_mand + n_opt);
     }
+    if (error) {
+        rb_error_arity(arg.argc, arg.n_mand, arg.f_var ? UNLIMITED_ARGUMENTS : arg.n_mand + arg.n_opt);
+    }
+    return arg.argc;
+}
 
-    return argc;
+int
+rb_scan_args_kw(int kw_flag, int argc, const VALUE *argv, const char *fmt, ...)
+{
+    int error;
+    va_list vargs;
+    VALUE tmp_buffer = 0;
+    struct rb_scan_args_t arg;
+    arg.tmp_buffer = &tmp_buffer;
+    rb_scan_args_parse(kw_flag, argc, argv, fmt, &arg);
+    va_start(vargs,fmt);
+    error = rb_scan_args_assign(&arg, vargs);
+    va_end(vargs);
+    if (tmp_buffer) {
+        rb_free_tmp_buffer(&tmp_buffer);
+    }
+    if (error) {
+        rb_error_arity(arg.argc, arg.n_mand, arg.f_var ? UNLIMITED_ARGUMENTS : arg.n_mand + arg.n_opt);
+    }
+    return arg.argc;
 }
 
 int

dir.c

@@ -2900,7 +2900,7 @@ dir_s_glob(int argc, VALUE *argv, VALUE obj)
 static VALUE
 dir_open_dir(int argc, VALUE *argv)
 {
-    VALUE dir = rb_funcallv(rb_cDir, rb_intern("open"), argc, argv);
+    VALUE dir = rb_funcallv_kw(rb_cDir, rb_intern("open"), argc, argv, RB_PASS_CALLED_KEYWORDS);
 
     rb_check_typeddata(dir, &dir_data_type);
     return dir;

error.c

@@ -341,7 +341,7 @@ rb_warn_m(int argc, VALUE *argv, VALUE exc)
     VALUE opts, location = Qnil;
 
     if (!NIL_P(ruby_verbose) && argc > 0 &&
-	    (argc = rb_scan_args(argc, argv, "*:", NULL, &opts)) > 0) {
+            (argc = rb_scan_args(argc, argv, "*:", NULL, &opts)) > 0) {
 	VALUE str = argv[0], uplevel = Qnil;
 	if (!NIL_P(opts)) {
 	    static ID kwds[1];
@@ -1595,7 +1595,7 @@ nometh_err_initialize(int argc, VALUE *argv, VALUE self)
     priv = (argc > 3) && (--argc, RTEST(argv[argc]));
     args = (argc > 2) ? argv[--argc] : Qnil;
     if (!NIL_P(options)) argv[argc++] = options;
-    rb_call_super(argc, argv);
+    rb_call_super_kw(argc, argv, RB_PASS_CALLED_KEYWORDS);
     return nometh_err_init_attr(self, args, priv);
 }
 

ext/-test-/scan_args/scan_args.c

@@ -250,6 +250,33 @@ scan_args_lead_opt_var_trail_hash(int argc, VALUE *argv, VALUE self)
     return rb_ary_new_from_values(numberof(args), args);
 }
 
+static VALUE
+scan_args_k_lead_opt_hash(int argc, VALUE *argv, VALUE self)
+{
+    VALUE args[4];
+    int n = rb_scan_args_kw(RB_SCAN_ARGS_KEYWORDS, argc, argv, "11:", args+1, args+2, args+3);
+    args[0] = INT2NUM(n);
+    return rb_ary_new_from_values(numberof(args), args);
+}
+
+static VALUE
+scan_args_e_lead_opt_hash(int argc, VALUE *argv, VALUE self)
+{
+    VALUE args[4];
+    int n = rb_scan_args_kw(RB_SCAN_ARGS_EMPTY_KEYWORDS, argc, argv, "11:", args+1, args+2, args+3);
+    args[0] = INT2NUM(n);
+    return rb_ary_new_from_values(numberof(args), args);
+}
+
+static VALUE
+scan_args_n_lead_opt_hash(int argc, VALUE *argv, VALUE self)
+{
+    VALUE args[4];
+    int n = rb_scan_args_kw(RB_SCAN_ARGS_LAST_HASH_KEYWORDS, argc, argv, "11:", args+1, args+2, args+3);
+    args[0] = INT2NUM(n);
+    return rb_ary_new_from_values(numberof(args), args);
+}
+
 void
 Init_scan_args(void)
 {
@@ -282,5 +309,7 @@ Init_scan_args(void)
     rb_define_singleton_method(module, "lead_var_trail_hash", scan_args_lead_var_trail_hash, -1);
     rb_define_singleton_method(module, "opt_var_trail_hash", scan_args_opt_var_trail_hash, -1);
     rb_define_singleton_method(module, "lead_opt_var_trail_hash", scan_args_lead_opt_var_trail_hash, -1);
+    rb_define_singleton_method(module, "k_lead_opt_hash", scan_args_k_lead_opt_hash, -1);
+    rb_define_singleton_method(module, "e_lead_opt_hash", scan_args_e_lead_opt_hash, -1);
+    rb_define_singleton_method(module, "n_lead_opt_hash", scan_args_n_lead_opt_hash, -1);
 }
-

ext/json/lib/json/common.rb

@@ -153,7 +153,7 @@ module JSON
   # * *object_class*: Defaults to Hash
   # * *array_class*: Defaults to Array
   def parse(source, opts = {})
-    Parser.new(source, opts).parse
+    Parser.new(source, **(opts||{})).parse
   end
 
   # Parse the JSON document _source_ into a Ruby data structure and return it.
@@ -176,7 +176,7 @@ module JSON
       :max_nesting  => false,
       :allow_nan    => true
     }.merge(opts)
-    Parser.new(source, opts).parse
+    Parser.new(source, **(opts||{})).parse
   end
 
   # Generate a JSON document from the Ruby data structure _obj_ and return

ext/json/parser/parser.c

@@ -1835,7 +1835,7 @@ static VALUE cParser_initialize(int argc, VALUE *argv, VALUE self)
     } else {
         json->max_nesting = 100;
         json->allow_nan = 0;
-        json->create_additions = 1;
+        json->create_additions = 0;
         json->create_id = rb_funcall(mJSON, i_create_id, 0);
         json->object_class = Qnil;
         json->array_class = Qnil;

ext/pathname/pathname.c

@@ -393,7 +393,7 @@ path_read(int argc, VALUE *argv, VALUE self)
 
     args[0] = get_strpath(self);
     n = rb_scan_args(argc, argv, "03", &args[1], &args[2], &args[3]);
-    return rb_funcallv(rb_cFile, id_read, 1+n, args);
+    return rb_funcallv_kw(rb_cFile, id_read, 1+n, args, RB_PASS_CALLED_KEYWORDS);
 }
 
 /*
@@ -1097,12 +1097,12 @@ path_s_glob(int argc, VALUE *argv, VALUE klass)
 
     n = rb_scan_args(argc, argv, "12", &args[0], &args[1], &args[2]);
     if (rb_block_given_p()) {
-        return rb_block_call(rb_cDir, id_glob, n, args, s_glob_i, klass);
+        return rb_block_call_kw(rb_cDir, id_glob, n, args, s_glob_i, klass, RB_PASS_CALLED_KEYWORDS);
     }
     else {
         VALUE ary;
         long i;
-        ary = rb_funcallv(rb_cDir, id_glob, n, args);
+        ary = rb_funcallv_kw(rb_cDir, id_glob, n, args, RB_PASS_CALLED_KEYWORDS);
         ary = rb_convert_type(ary, T_ARRAY, "Array", "to_ary");
         for (i = 0; i < RARRAY_LEN(ary); i++) {
             VALUE elt = RARRAY_AREF(ary, i);
@@ -1145,12 +1145,12 @@ path_glob(int argc, VALUE *argv, VALUE self)
     n = 3;
 
     if (rb_block_given_p()) {
-        return rb_block_call(rb_cDir, id_glob, n, args, glob_i, self);
+        return rb_block_call_kw(rb_cDir, id_glob, n, args, glob_i, self, RB_PASS_KEYWORDS);
     }
     else {
         VALUE ary;
         long i;
-        ary = rb_funcallv(rb_cDir, id_glob, n, args);
+        ary = rb_funcallv_kw(rb_cDir, id_glob, n, args, RB_PASS_KEYWORDS);
         ary = rb_convert_type(ary, T_ARRAY, "Array", "to_ary");
         for (i = 0; i < RARRAY_LEN(ary); i++) {
             VALUE elt = RARRAY_AREF(ary, i);

ext/stringio/stringio.c

@@ -385,7 +385,7 @@ strio_finalize(VALUE self)
 static VALUE
 strio_s_open(int argc, VALUE *argv, VALUE klass)
 {
-    VALUE obj = rb_class_new_instance(argc, argv, klass);
+    VALUE obj = rb_class_new_instance_kw(argc, argv, klass, RB_PASS_CALLED_KEYWORDS);
     if (!rb_block_given_p()) return obj;
     return rb_ensure(rb_yield, obj, strio_finalize, obj);
 }
@@ -400,7 +400,7 @@ strio_s_new(int argc, VALUE *argv, VALUE klass)
 	rb_warn("%"PRIsVALUE"::new() does not take block; use %"PRIsVALUE"::open() instead",
 		cname, cname);
     }
-    return rb_class_new_instance(argc, argv, klass);
+    return rb_class_new_instance_kw(argc, argv, klass, RB_PASS_CALLED_KEYWORDS);
 }
 
 /*

ext/zlib/zlib.c

@@ -3045,7 +3045,7 @@ static VALUE
 new_wrap(VALUE tmp)
 {
     new_wrap_arg_t *arg = (new_wrap_arg_t *)tmp;
-    return rb_class_new_instance(arg->argc, arg->argv, arg->klass);
+    return rb_class_new_instance_kw(arg->argc, arg->argv, arg->klass, RB_PASS_CALLED_KEYWORDS);
 }
 
 static VALUE
@@ -3078,7 +3078,7 @@ gzfile_wrap(int argc, VALUE *argv, VALUE klass, int close_io_on_error)
 	}
     }
     else {
-	obj = rb_class_new_instance(argc, argv, klass);
+	obj = rb_class_new_instance_kw(argc, argv, klass, RB_PASS_CALLED_KEYWORDS);
     }
 
     if (rb_block_given_p()) {

include/ruby/ruby.h

@@ -1899,6 +1899,11 @@ VALUE rb_funcall_passing_block(VALUE, ID, int, const VALUE*);
 VALUE rb_funcall_with_block(VALUE, ID, int, const VALUE*, VALUE);
 VALUE rb_funcall_with_block_kw(VALUE, ID, int, const VALUE*, VALUE, int);
 int rb_scan_args(int, const VALUE*, const char*, ...);
+#define RB_SCAN_ARGS_PASS_CALLED_KEYWORDS 0
+#define RB_SCAN_ARGS_KEYWORDS 1
+#define RB_SCAN_ARGS_EMPTY_KEYWORDS 2
+#define RB_SCAN_ARGS_LAST_HASH_KEYWORDS 3
+int rb_scan_args_kw(int, int, const VALUE*, const char*, ...);
 VALUE rb_call_super(int, const VALUE*);
 VALUE rb_call_super_kw(int, const VALUE*, int);
 VALUE rb_current_receiver(void);
@@ -2324,6 +2329,9 @@ unsigned long ruby_strtoul(const char *str, char **endptr, int base);
 PRINTF_ARGS(int ruby_snprintf(char *str, size_t n, char const *fmt, ...), 3, 4);
 int ruby_vsnprintf(char *str, size_t n, char const *fmt, va_list ap);
 
+/* -- Remove In 3.0, Only public for rb_scan_args optimized version -- */
+int rb_empty_keyword_given_p(void);
+
 #if defined(HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P) && defined(HAVE_VA_ARGS_MACRO) && defined(__OPTIMIZE__)
 # define rb_scan_args(argc,argvp,fmt,...) \
     __builtin_choose_expr(__builtin_constant_p(fmt), \
@@ -2519,30 +2527,81 @@ rb_scan_args_set(int argc, const VALUE *argv,
     int i, argi = 0, vari = 0, last_idx = -1;
     VALUE *var, hash = Qnil, last_hash = 0;
     const int n_mand = n_lead + n_trail;
+    int keyword_given = rb_keyword_given_p();
+    int empty_keyword_given = 0;
+    VALUE tmp_buffer = 0;
 
-    /* capture an option hash - phase 1: pop */
+    if (!keyword_given) {
-    if (f_hash && n_mand < argc) {
+        empty_keyword_given = rb_empty_keyword_given_p();
-	VALUE last = argv[argc - 1];
-
-	if (RB_NIL_P(last)) {
-	    /* nil is taken as an empty option hash only if it is not
-	       ambiguous; i.e. '*' is not specified and arguments are
-	       given more than sufficient */
-	    if (!f_var && n_mand + n_opt < argc)
-		argc--;
-	}
-	else {
-	    hash = rb_check_hash_type(last);
-	    if (!RB_NIL_P(hash)) {
-		VALUE opts = rb_extract_keywords(&hash);
-		if (!(last_hash = hash)) argc--;
-		else last_idx = argc - 1;
-		hash = opts ? opts : Qnil;
-	    }
-	}
     }
 
-    rb_check_arity(argc, n_mand, f_var ? UNLIMITED_ARGUMENTS : n_mand + n_opt);
+    /* capture an option hash - phase 1: pop */
+    /* Ignore final positional hash if empty keywords given */
+    if (argc > 0 && !(f_hash && empty_keyword_given)) {
+        VALUE last = argv[argc - 1];
+
+        if (f_hash && n_mand < argc) {
+            if (keyword_given) {
+                if (!RB_TYPE_P(last, T_HASH)) {
+                    rb_warn("Keyword flag set when calling rb_scan_args, but last entry is not a hash");
+                }
+                else {
+                    hash = last;
+                }
+            }
+            else if (NIL_P(last)) {
+                /* For backwards compatibility, nil is taken as an empty
+                   option hash only if it is not ambiguous; i.e. '*' is
+                   not specified and arguments are given more than sufficient.
+                   This will be removed in Ruby 3. */
+                if (!f_var && n_mand + n_opt < argc) {
+                    rb_warn("The last argument is nil, treating as empty keywords");
+                    argc--;
+                }
+            }
+            else {
+                hash = rb_check_hash_type(last);
+            }
+
+            /* Ruby 3: Remove if branch, as it will not attempt to split hashes */
+            if (!NIL_P(hash)) {
+                VALUE opts = rb_extract_keywords(&hash);
+
+                if (!(last_hash = hash)) {
+                    if (!keyword_given) {
+                        /* Warn if treating positional as keyword, as in Ruby 3,
+                           this will be an error */
+                        rb_warn("The last argument is used as the keyword parameter");
+                    }
+                    argc--;
+                }
+                else {
+                    /* Warn if splitting either positional hash to keywords or keywords
+                       to positional hash, as in Ruby 3, no splitting will be done */
+                    rb_warn("The last argument is split into positional and keyword parameters");
+                    last_idx = argc - 1;
+                }
+                hash = opts ? opts : Qnil;
+            }
+        }
+        else if (f_hash && keyword_given && n_mand == argc) {
+            /* Warn if treating keywords as positional, as in Ruby 3, this will be an error */
+            rb_warn("The keyword argument is passed as the last hash parameter");
+        }
+    }
+    if (f_hash && n_mand == argc+1 && empty_keyword_given) {
+        VALUE *ptr = (VALUE *)rb_alloc_tmp_buffer2(&tmp_buffer, argc+1, sizeof(VALUE));
+        memcpy(ptr, argv, sizeof(VALUE)*argc);
+        ptr[argc] = rb_hash_new();
+        argc++;
+        *(&argv) = ptr;
+        rb_warn("The keyword argument is passed as the last hash parameter");
+    }
+
+
+    if (argc < n_mand) {
+        goto argc_error;
+    }
 
     /* capture leading mandatory arguments */
     for (i = n_lead; i-- > 0; ) {
@@ -2600,6 +2659,13 @@ rb_scan_args_set(int argc, const VALUE *argv,
 	}
     }
 
+    if (argi < argc) {
+      argc_error:
+        if(tmp_buffer) rb_free_tmp_buffer(&tmp_buffer);
+        rb_error_arity(argc, n_mand, f_var ? UNLIMITED_ARGUMENTS : n_mand + n_opt);
+    }
+
+    if(tmp_buffer) rb_free_tmp_buffer(&tmp_buffer);
     return argc;
 }
 #endif

internal.h

@@ -1552,9 +1552,6 @@ void rb_class_modify_check(VALUE);
 #define id_status ruby_static_id_status
 NORETURN(VALUE rb_f_raise(int argc, VALUE *argv));
 
-/* -- Remove In 3.0 -- */
-int rb_empty_keyword_given_p(void);
-
 /* eval_error.c */
 VALUE rb_get_backtrace(VALUE info);
 

io.c

@@ -7022,7 +7022,7 @@ rb_open_file(int argc, const VALUE *argv, VALUE io)
 static VALUE
 rb_io_s_open(int argc, VALUE *argv, VALUE klass)
 {
-    VALUE io = rb_class_new_instance(argc, argv, klass);
+    VALUE io = rb_class_new_instance_kw(argc, argv, klass, RB_PASS_CALLED_KEYWORDS);
 
     if (rb_block_given_p()) {
 	return rb_ensure(rb_yield, io, io_close, io);
@@ -7209,7 +7209,7 @@ rb_f_open(int argc, VALUE *argv, VALUE _)
 	}
     }
     if (redirect) {
-	VALUE io = rb_funcallv(argv[0], to_open, argc-1, argv+1);
+        VALUE io = rb_funcallv_kw(argv[0], to_open, argc-1, argv+1, RB_PASS_CALLED_KEYWORDS);
 
 	if (rb_block_given_p()) {
 	    return rb_ensure(rb_yield, io, io_close, io);
@@ -8390,7 +8390,7 @@ rb_io_s_new(int argc, VALUE *argv, VALUE klass)
 	rb_warn("%"PRIsVALUE"::new() does not take block; use %"PRIsVALUE"::open() instead",
 		cname, cname);
     }
-    return rb_class_new_instance(argc, argv, klass);
+    return rb_class_new_instance_kw(argc, argv, klass, RB_PASS_CALLED_KEYWORDS);
 }
 
 
@@ -10373,7 +10373,7 @@ open_key_args(VALUE klass, int argc, VALUE *argv, VALUE opt, struct foreach_arg
 	v = rb_to_array_type(v);
 	n = RARRAY_LENINT(v);
 	rb_check_arity(n, 0, 3); /* rb_io_open */
-	rb_scan_args(n, RARRAY_CONST_PTR(v), "02:", &vmode, &vperm, &opt);
+        rb_scan_args_kw(RB_SCAN_ARGS_LAST_HASH_KEYWORDS, n, RARRAY_CONST_PTR(v), "02:", &vmode, &vperm, &opt);
     }
     arg->io = rb_io_open(klass, path, vmode, vperm, opt);
 }

lib/csv.rb

@@ -637,7 +637,7 @@ class CSV
     file_opts = {universal_newline: false}.merge(options)
 
     begin
-      f = File.open(filename, mode, file_opts)
+      f = File.open(filename, mode, **file_opts)
     rescue ArgumentError => e
       raise unless /needs binmode/.match?(e.message) and mode == "r"
       mode = "rb"

lib/fileutils.rb

@@ -1276,9 +1276,9 @@ module FileUtils
       opts[:encoding] = ::Encoding::UTF_8 if fu_windows?
 
       files = if Dir.respond_to?(:children)
-        Dir.children(path, opts)
+        Dir.children(path, **opts)
       else
-        Dir.entries(path(), opts)
+        Dir.entries(path(), **opts)
            .reject {|n| n == '.' or n == '..' }
       end
 

lib/open-uri.rb

@@ -10,15 +10,15 @@ module Kernel
     alias open_uri_original_open open # :nodoc:
   end
 
-  def open(name, *rest, &block) # :nodoc:
+  def open(name, *rest, **kw, &block) # :nodoc:
     if (name.respond_to?(:open) && !name.respond_to?(:to_path)) ||
        (name.respond_to?(:to_str) &&
         %r{\A[A-Za-z][A-Za-z0-9+\-\.]*://} =~ name &&
         (uri = URI.parse(name)).respond_to?(:open))
       warn('calling URI.open via Kernel#open is deprecated, call URI.open directly', uplevel: 1)
-      URI.open(name, *rest, &block)
+      URI.open(name, *rest, **kw, &block)
     else
-      open_uri_original_open(name, *rest, &block)
+      open_uri_original_open(name, *rest, **kw, &block)
     end
   end
   module_function :open

lib/pstore.rb

@@ -374,7 +374,7 @@ class PStore
   def open_and_lock_file(filename, read_only)
     if read_only
       begin
-        file = File.new(filename, RD_ACCESS)
+        file = File.new(filename, **RD_ACCESS)
         begin
           file.flock(File::LOCK_SH)
           return file
@@ -386,7 +386,7 @@ class PStore
         return nil
       end
     else
-      file = File.new(filename, RDWR_ACCESS)
+      file = File.new(filename, **RDWR_ACCESS)
       file.flock(File::LOCK_EX)
       return file
     end
@@ -449,7 +449,7 @@ class PStore
 
   def save_data_with_atomic_file_rename_strategy(data, file)
     temp_filename = "#{@filename}.tmp.#{Process.pid}.#{rand 1000000}"
-    temp_file = File.new(temp_filename, WR_ACCESS)
+    temp_file = File.new(temp_filename, **WR_ACCESS)
     begin
       temp_file.flock(File::LOCK_EX)
       temp_file.write(data)

lib/rubygems/core_ext/kernel_warn.rb

@@ -12,9 +12,9 @@ if RUBY_VERSION >= "2.5"
 
     original_warn = method(:warn)
 
-    module_function define_method(:warn) {|*messages, uplevel: nil|
+    module_function define_method(:warn) {|*messages, **kw|
-      unless uplevel
+      unless uplevel = kw[:uplevel]
-        return original_warn.call(*messages)
+        return original_warn.call(*messages, **kw)
       end
 
       # Ensure `uplevel` fits a `long`
@@ -39,7 +39,8 @@ if RUBY_VERSION >= "2.5"
         end
         uplevel = start
       end
-      original_warn.call(*messages, uplevel: uplevel)
+      kw[:uplevel] = uplevel
+      original_warn.call(*messages, **kw)
     }
   end
 end

lib/rubygems/package.rb

@@ -529,11 +529,11 @@ EOM
     when 'metadata' then
       @spec = Gem::Specification.from_yaml entry.read
     when 'metadata.gz' then
-      args = [entry]
+      opts = {}
-      args << { :external_encoding => Encoding::UTF_8 } if
+      opts[:external_encoding] = Encoding::UTF_8 if
         Zlib::GzipReader.method(:wrap).arity != 1
 
-      Zlib::GzipReader.wrap(*args) do |gzio|
+      Zlib::GzipReader.wrap(entry, **opts) do |gzio|
         @spec = Gem::Specification.from_yaml gzio.read
       end
     end

lib/tempfile.rb

@@ -130,7 +130,7 @@ class Tempfile < DelegateClass(File)
     @mode = mode|File::RDWR|File::CREAT|File::EXCL
     ::Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
       opts[:perm] = 0600
-      @tmpfile = File.open(tmpname, @mode, opts)
+      @tmpfile = File.open(tmpname, @mode, **opts)
       @opts = opts.freeze
     end
     ObjectSpace.define_finalizer(self, Remover.new(@tmpfile))
@@ -142,7 +142,7 @@ class Tempfile < DelegateClass(File)
   def open
     _close
     mode = @mode & ~(File::CREAT|File::EXCL)
-    @tmpfile = File.open(@tmpfile.path, mode, @opts)
+    @tmpfile = File.open(@tmpfile.path, mode, **@opts)
     __setobj__(@tmpfile)
   end
 
@@ -329,7 +329,7 @@ def Tempfile.create(basename="", tmpdir=nil, mode: 0, **options)
   Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
     mode |= File::RDWR|File::CREAT|File::EXCL
     opts[:perm] = 0600
-    tmpfile = File.open(tmpname, mode, opts)
+    tmpfile = File.open(tmpname, mode, **opts)
   end
   if block_given?
     begin

rational.c

@@ -1543,7 +1543,7 @@ nurat_round_n(int argc, VALUE *argv, VALUE self)
 {
     VALUE opt;
     enum ruby_num_rounding_mode mode = (
-	argc = rb_scan_args(argc, argv, "*:", NULL, &opt),
+        argc = rb_scan_args(argc, argv, "*:", NULL, &opt),
 	rb_num_get_rounding_option(opt));
     VALUE (*round_func)(VALUE) = ROUND_FUNC(mode, nurat_round);
     return f_round_common(argc, argv, self, round_func);

test/-ext-/test_scan_args.rb

@@ -93,7 +93,14 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([1, "a", nil], Bug::ScanArgs.lead_hash("a"))
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_hash("a", "b")}
     assert_equal([1, "a", {b: 1}], Bug::ScanArgs.lead_hash("a", b: 1))
-    assert_equal([1, {b: 1}, nil], Bug::ScanArgs.lead_hash(b: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {b: 1}, nil], Bug::ScanArgs.lead_hash(b: 1))
+    end
+    assert_equal([1, {"a"=>0, b: 1}, nil], Bug::ScanArgs.lead_hash({"a"=>0, b: 1}, **{}))
+    assert_raise(ArgumentError) {Bug::ScanArgs.lead_hash(1, {"a"=>0, b: 1}, **{})}
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {}, nil], Bug::ScanArgs.lead_hash(**{}))
+    end
   end
 
   def test_opt_hash
@@ -102,7 +109,10 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([0, nil, {b: 1}], Bug::ScanArgs.opt_hash(b: 1))
     assert_equal([1, "a", {b: 1}], Bug::ScanArgs.opt_hash("a", b: 1))
     assert_raise(ArgumentError) {Bug::ScanArgs.opt_hash("a", "b")}
-    assert_equal([1, {"a"=>0}, {b: 1}], Bug::ScanArgs.opt_hash("a"=>0, b: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([1, {"a"=>0}, {b: 1}], Bug::ScanArgs.opt_hash("a"=>0, b: 1))
+    end
+    assert_equal([1, {"a"=>0, b: 1}, nil], Bug::ScanArgs.opt_hash({"a"=>0, b: 1}, **{}))
   end
 
   def test_lead_opt_hash
@@ -110,9 +120,13 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([2, "a", "b", nil], Bug::ScanArgs.lead_opt_hash("a", "b"))
     assert_equal([1, "a", nil, {c: 1}], Bug::ScanArgs.lead_opt_hash("a", c: 1))
     assert_equal([2, "a", "b", {c: 1}], Bug::ScanArgs.lead_opt_hash("a", "b", c: 1))
-    assert_equal([1, {c: 1}, nil, nil], Bug::ScanArgs.lead_opt_hash(c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {c: 1}, nil, nil], Bug::ScanArgs.lead_opt_hash(c: 1))
+    end
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_opt_hash("a", "b", "c")}
-    assert_equal([2, "a", {"b"=>0}, {c: 1}], Bug::ScanArgs.lead_opt_hash("a", "b"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([2, "a", {"b"=>0}, {c: 1}], Bug::ScanArgs.lead_opt_hash("a", "b"=>0, c: 1))
+    end
   end
 
   def test_var_hash
@@ -120,7 +134,9 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([1, ["a"], nil], Bug::ScanArgs.var_hash("a"))
     assert_equal([1, ["a"], {b: 1}], Bug::ScanArgs.var_hash("a", b: 1))
     assert_equal([0, [], {b: 1}], Bug::ScanArgs.var_hash(b: 1))
-    assert_equal([1, [{"a"=>0}], {b: 1}], Bug::ScanArgs.var_hash("a"=>0, b: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([1, [{"a"=>0}], {b: 1}], Bug::ScanArgs.var_hash("a"=>0, b: 1))
+    end
   end
 
   def test_lead_var_hash
@@ -129,9 +145,13 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([2, "a", ["b"], nil], Bug::ScanArgs.lead_var_hash("a", "b"))
     assert_equal([2, "a", ["b"], {c: 1}], Bug::ScanArgs.lead_var_hash("a", "b", c: 1))
     assert_equal([1, "a", [], {c: 1}], Bug::ScanArgs.lead_var_hash("a", c: 1))
-    assert_equal([1, {c: 1}, [], nil], Bug::ScanArgs.lead_var_hash(c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {c: 1}, [], nil], Bug::ScanArgs.lead_var_hash(c: 1))
+    end
     assert_equal([3, "a", ["b", "c"], nil], Bug::ScanArgs.lead_var_hash("a", "b", "c"))
-    assert_equal([2, "a", [{"b"=>0}], {c: 1}], Bug::ScanArgs.lead_var_hash("a", "b"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([2, "a", [{"b"=>0}], {c: 1}], Bug::ScanArgs.lead_var_hash("a", "b"=>0, c: 1))
+    end
   end
 
   def test_opt_var_hash
@@ -142,7 +162,9 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([1, "a", [], {c: 1}], Bug::ScanArgs.opt_var_hash("a", c: 1))
     assert_equal([0, nil, [], {c: 1}], Bug::ScanArgs.opt_var_hash(c: 1))
     assert_equal([3, "a", ["b", "c"], nil], Bug::ScanArgs.opt_var_hash("a", "b", "c"))
-    assert_equal([2, "a", [{"b"=>0}], {c: 1}], Bug::ScanArgs.opt_var_hash("a", "b"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([2, "a", [{"b"=>0}], {c: 1}], Bug::ScanArgs.opt_var_hash("a", "b"=>0, c: 1))
+    end
   end
 
   def test_lead_opt_var_hash
@@ -151,10 +173,14 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([2, "a", "b", [], nil], Bug::ScanArgs.lead_opt_var_hash("a", "b"))
     assert_equal([2, "a", "b", [], {c: 1}], Bug::ScanArgs.lead_opt_var_hash("a", "b", c: 1))
     assert_equal([1, "a", nil, [], {c: 1}], Bug::ScanArgs.lead_opt_var_hash("a", c: 1))
-    assert_equal([1, {c: 1}, nil, [], nil], Bug::ScanArgs.lead_opt_var_hash(c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {c: 1}, nil, [], nil], Bug::ScanArgs.lead_opt_var_hash(c: 1))
+    end
     assert_equal([3, "a", "b", ["c"], nil], Bug::ScanArgs.lead_opt_var_hash("a", "b", "c"))
     assert_equal([3, "a", "b", ["c"], {d: 1}], Bug::ScanArgs.lead_opt_var_hash("a", "b", "c", d: 1))
-    assert_equal([3, "a", "b", [{"c"=>0}], {d: 1}], Bug::ScanArgs.lead_opt_var_hash("a", "b", "c"=>0, d: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([3, "a", "b", [{"c"=>0}], {d: 1}], Bug::ScanArgs.lead_opt_var_hash("a", "b", "c"=>0, d: 1))
+    end
   end
 
   def test_opt_trail_hash
@@ -163,9 +189,13 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([2, "a", "b", nil], Bug::ScanArgs.opt_trail_hash("a", "b"))
     assert_equal([1, nil, "a", {c: 1}], Bug::ScanArgs.opt_trail_hash("a", c: 1))
     assert_equal([2, "a", "b", {c: 1}], Bug::ScanArgs.opt_trail_hash("a", "b", c: 1))
-    assert_equal([1, nil, {c: 1}, nil], Bug::ScanArgs.opt_trail_hash(c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, nil, {c: 1}, nil], Bug::ScanArgs.opt_trail_hash(c: 1))
+    end
     assert_raise(ArgumentError) {Bug::ScanArgs.opt_trail_hash("a", "b", "c")}
-    assert_equal([2, "a", {"b"=>0}, {c: 1}], Bug::ScanArgs.opt_trail_hash("a", "b"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([2, "a", {"b"=>0}, {c: 1}], Bug::ScanArgs.opt_trail_hash("a", "b"=>0, c: 1))
+    end
   end
 
   def test_lead_opt_trail_hash
@@ -173,12 +203,16 @@ class TestScanArgs < Test::Unit::TestCase
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_opt_trail_hash("a")}
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_opt_trail_hash(c: 1)}
     assert_equal([2, "a", nil, "b", nil], Bug::ScanArgs.lead_opt_trail_hash("a", "b"))
-    assert_equal([2, "a", nil, {c: 1}, nil], Bug::ScanArgs.lead_opt_trail_hash("a", c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([2, "a", nil, {c: 1}, nil], Bug::ScanArgs.lead_opt_trail_hash("a", c: 1))
+    end
     assert_equal([2, "a", nil, "b", {c: 1}], Bug::ScanArgs.lead_opt_trail_hash("a", "b", c: 1))
     assert_equal([3, "a", "b", "c", nil], Bug::ScanArgs.lead_opt_trail_hash("a", "b", "c"))
     assert_equal([3, "a", "b", "c", {c: 1}], Bug::ScanArgs.lead_opt_trail_hash("a", "b", "c", c: 1))
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_opt_trail_hash("a", "b", "c", "d")}
-    assert_equal([3, "a", "b", {"c"=>0}, {c: 1}], Bug::ScanArgs.lead_opt_trail_hash("a", "b", "c"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([3, "a", "b", {"c"=>0}, {c: 1}], Bug::ScanArgs.lead_opt_trail_hash("a", "b", "c"=>0, c: 1))
+    end
   end
 
   def test_var_trail_hash
@@ -187,45 +221,104 @@ class TestScanArgs < Test::Unit::TestCase
     assert_equal([2, ["a"], "b", nil], Bug::ScanArgs.var_trail_hash("a", "b"))
     assert_equal([1, [], "a", {c: 1}], Bug::ScanArgs.var_trail_hash("a", c: 1))
     assert_equal([2, ["a"], "b", {c: 1}], Bug::ScanArgs.var_trail_hash("a", "b", c: 1))
-    assert_equal([1, [], {c: 1}, nil], Bug::ScanArgs.var_trail_hash(c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, [], {c: 1}, nil], Bug::ScanArgs.var_trail_hash(c: 1))
+    end
     assert_equal([3, ["a", "b"], "c", nil], Bug::ScanArgs.var_trail_hash("a", "b", "c"))
     assert_equal([3, ["a", "b"], "c", {c: 1}], Bug::ScanArgs.var_trail_hash("a", "b", "c", c: 1))
-    assert_equal([3, ["a", "b"], {"c"=>0}, {c: 1}], Bug::ScanArgs.var_trail_hash("a", "b", "c"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([3, ["a", "b"], {"c"=>0}, {c: 1}], Bug::ScanArgs.var_trail_hash("a", "b", "c"=>0, c: 1))
+    end
   end
 
   def test_lead_var_trail_hash
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_var_trail_hash()}
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_var_trail_hash("a")}
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_var_trail_hash(c: 1)}
-    assert_equal([2, "a", [], {c: 1}, nil], Bug::ScanArgs.lead_var_trail_hash("a", c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([2, "a", [], {c: 1}, nil], Bug::ScanArgs.lead_var_trail_hash("a", c: 1))
+    end
     assert_equal([2, "a", [], "b", nil], Bug::ScanArgs.lead_var_trail_hash("a", "b"))
     assert_equal([2, "a", [], "b", {c: 1}], Bug::ScanArgs.lead_var_trail_hash("a", "b", c: 1))
     assert_equal([3, "a", ["b"], "c", nil], Bug::ScanArgs.lead_var_trail_hash("a", "b", "c"))
     assert_equal([3, "a", ["b"], "c", {c: 1}], Bug::ScanArgs.lead_var_trail_hash("a", "b", "c", c: 1))
-    assert_equal([3, "a", ["b"], {"c"=>0}, {c: 1}], Bug::ScanArgs.lead_var_trail_hash("a", "b", c: 1, "c"=>0))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([3, "a", ["b"], {"c"=>0}, {c: 1}], Bug::ScanArgs.lead_var_trail_hash("a", "b", c: 1, "c"=>0))
+    end
   end
 
   def test_opt_var_trail_hash
     assert_raise(ArgumentError) {Bug::ScanArgs.opt_var_trail_hash()}
     assert_equal([1, nil, [], "a", nil], Bug::ScanArgs.opt_var_trail_hash("a"))
-    assert_equal([1, nil, [], {c: 1}, nil], Bug::ScanArgs.opt_var_trail_hash(c: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, nil, [], {c: 1}, nil], Bug::ScanArgs.opt_var_trail_hash(c: 1))
+    end
     assert_equal([1, nil, [], "a", {c: 1}], Bug::ScanArgs.opt_var_trail_hash("a", c: 1))
     assert_equal([2, "a", [], "b", nil], Bug::ScanArgs.opt_var_trail_hash("a", "b"))
     assert_equal([2, "a", [], "b", {c: 1}], Bug::ScanArgs.opt_var_trail_hash("a", "b", c: 1))
     assert_equal([3, "a", ["b"], "c", nil], Bug::ScanArgs.opt_var_trail_hash("a", "b", "c"))
     assert_equal([3, "a", ["b"], "c", {c: 1}], Bug::ScanArgs.opt_var_trail_hash("a", "b", "c", c: 1))
-    assert_equal([3, "a", ["b"], {"c"=>0}, {c: 1}], Bug::ScanArgs.opt_var_trail_hash("a", "b", "c"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([3, "a", ["b"], {"c"=>0}, {c: 1}], Bug::ScanArgs.opt_var_trail_hash("a", "b", "c"=>0, c: 1))
+    end
   end
 
   def test_lead_opt_var_trail_hash
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_opt_var_trail_hash()}
     assert_raise(ArgumentError) {Bug::ScanArgs.lead_opt_var_trail_hash("a")}
-    assert_equal([2, "a", nil, [], {b: 1}, nil], Bug::ScanArgs.lead_opt_var_trail_hash("a", b: 1))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([2, "a", nil, [], {b: 1}, nil], Bug::ScanArgs.lead_opt_var_trail_hash("a", b: 1))
+    end
     assert_equal([2, "a", nil, [], "b", nil], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b"))
     assert_equal([2, "a", nil, [], "b", {c: 1}], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b", c: 1))
     assert_equal([3, "a", "b", [], "c", nil], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b", "c"))
     assert_equal([3, "a", "b", [], "c", {c: 1}], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b", "c", c: 1))
     assert_equal([4, "a", "b", ["c"], "d", nil], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b", "c", "d"))
-    assert_equal([4, "a", "b", ["c"], {"d"=>0}, {c: 1}], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b", "c", "d"=>0, c: 1))
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([4, "a", "b", ["c"], {"d"=>0}, {c: 1}], Bug::ScanArgs.lead_opt_var_trail_hash("a", "b", "c", "d"=>0, c: 1))
+    end
+  end
+
+  def test_k_lead_opt_hash
+    assert_raise(ArgumentError) {Bug::ScanArgs.k_lead_opt_hash}
+    assert_equal([1, "a", nil, {c: 1}], Bug::ScanArgs.k_lead_opt_hash("a", c: 1))
+    assert_equal([1, "a", nil, {c: 1}], Bug::ScanArgs.k_lead_opt_hash("a", {c: 1}))
+    assert_equal([2, "a", "b", {c: 1}], Bug::ScanArgs.k_lead_opt_hash("a", "b", c: 1))
+    assert_equal([2, "a", "b", {c: 1}], Bug::ScanArgs.k_lead_opt_hash("a", "b", {c: 1}))
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {c: 1}, nil, nil], Bug::ScanArgs.k_lead_opt_hash(c: 1))
+    end
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([2, "a", {"b"=>0}, {c: 1}], Bug::ScanArgs.k_lead_opt_hash("a", "b"=>0, c: 1))
+    end
+  end
+
+  def test_e_lead_opt_hash
+    assert_warn(/The keyword argument is passed as the last hash parameter/) do
+      assert_equal([1, {}, nil, nil], Bug::ScanArgs.e_lead_opt_hash)
+    end
+    assert_equal([1, "a", nil, nil], Bug::ScanArgs.e_lead_opt_hash("a"))
+    assert_equal([2, "a", "b", nil], Bug::ScanArgs.e_lead_opt_hash("a", "b"))
+    assert_equal([2, "a", {c: 1}, nil], Bug::ScanArgs.e_lead_opt_hash("a", c: 1))
+    assert_raise(ArgumentError) {Bug::ScanArgs.e_lead_opt_hash("a", "b", c: 1)}
+    assert_equal([1, {c: 1}, nil, nil], Bug::ScanArgs.e_lead_opt_hash(c: 1))
+    assert_raise(ArgumentError) {Bug::ScanArgs.e_lead_opt_hash("a", "b", "c")}
+    assert_equal([2, "a", {"b"=>0, c: 1}, nil], Bug::ScanArgs.e_lead_opt_hash("a", "b"=>0, c: 1))
+  end
+
+  def test_n_lead_opt_hash
+    assert_raise(ArgumentError) {Bug::ScanArgs.n_lead_opt_hash}
+    assert_equal([1, "a", nil, nil], Bug::ScanArgs.n_lead_opt_hash("a"))
+    assert_equal([2, "a", "b", nil], Bug::ScanArgs.n_lead_opt_hash("a", "b"))
+    assert_equal([1, "a", nil, {c: 1}], Bug::ScanArgs.n_lead_opt_hash("a", c: 1))
+    assert_equal([1, "a", nil, {c: 1}], Bug::ScanArgs.n_lead_opt_hash("a", {c: 1}))
+    assert_equal([2, "a", "b", {c: 1}], Bug::ScanArgs.n_lead_opt_hash("a", "b", c: 1))
+    assert_equal([2, "a", "b", {c: 1}], Bug::ScanArgs.n_lead_opt_hash("a", "b", {c: 1}))
+    assert_equal([1, {c: 1}, nil, nil], Bug::ScanArgs.n_lead_opt_hash(c: 1))
+    assert_equal([1, {c: 1}, nil, nil], Bug::ScanArgs.n_lead_opt_hash({c: 1}))
+    assert_raise(ArgumentError) {Bug::ScanArgs.n_lead_opt_hash("a", "b", "c")}
+    assert_warn(/The last argument is split into positional and keyword parameters/) do
+      assert_equal([2, "a", {"b"=>0}, {c: 1}], Bug::ScanArgs.n_lead_opt_hash("a", "b"=>0, c: 1))
+    end
   end
 end

test/pathname/test_pathname.rb

@@ -933,7 +933,7 @@ class TestPathname < Test::Unit::TestCase
       assert_equal(0444 & ~File.umask, File.stat("b").mode & 0777)
       assert_equal("def", File.read("b"))
 
-      Pathname("c").open("w", 0444, {}) {|f| f.write "ghi" }
+      Pathname("c").open("w", 0444, **{}) {|f| f.write "ghi" }
       assert_equal(0444 & ~File.umask, File.stat("c").mode & 0777)
       assert_equal("ghi", File.read("c"))
 

test/reline/helper.rb

@@ -31,7 +31,7 @@ class Reline::TestCase < Test::Unit::TestCase
       if Reline::Unicode::EscapedChars.include?(c.ord)
         c
       else
-        c.encode(@line_editor.instance_variable_get(:@encoding), Encoding::UTF_8, options)
+        c.encode(@line_editor.instance_variable_get(:@encoding), Encoding::UTF_8, **options)
       end
     }.join
   rescue Encoding::UndefinedConversionError, Encoding::InvalidByteSequenceError

test/ruby/test_dir_m17n.rb

@@ -18,7 +18,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = #{code}.chr('UTF-8').force_encoding("#{encoding}")
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename)
       EOS
 
@@ -26,7 +26,7 @@ class TestDir_M17N < Test::Unit::TestCase
       assert_separately(%w[-EASCII-8BIT], <<-EOS, :chdir=>dir)
         filename = #{code}.chr('UTF-8').force_encoding("ASCII-8BIT")
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         expected_filename = #{code}.chr('UTF-8').encode(Encoding.find("filesystem")) rescue expected_filename = "?"
         expected_filename = expected_filename.force_encoding("ASCII-8BIT")
         if /mswin|mingw/ =~ RUBY_PLATFORM
@@ -35,7 +35,7 @@ class TestDir_M17N < Test::Unit::TestCase
           when ents.include?(expected_filename)
             filename = expected_filename
           else
-            ents = Dir.entries(".", {:encoding => Encoding.find("filesystem")})
+            ents = Dir.entries(".", :encoding => Encoding.find("filesystem"))
             filename = expected_filename
           end
         end
@@ -52,7 +52,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\u3042"
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename)
       EOS
     }
@@ -67,7 +67,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xff".force_encoding("ASCII-8BIT") # invalid byte sequence as UTF-8
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         filename = "%FF" if /darwin/ =~ RUBY_PLATFORM && ents.include?("%FF")
         assert_include(ents, filename)
       EOS
@@ -75,7 +75,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xff".force_encoding("UTF-8") # invalid byte sequence as UTF-8
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         filename = "%FF" if /darwin/ =~ RUBY_PLATFORM && ents.include?("%FF")
         assert_include(ents, filename)
       EOS
@@ -88,7 +88,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xc2\xa1".force_encoding("utf-8")
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename)
       EOS
       assert_separately(%w[-EUTF-8], <<-'EOS', :chdir=>d)
@@ -125,13 +125,13 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\u3042"
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename)
       EOS
       assert_separately(%w[-EUTF-8:EUC-JP], <<-'EOS', :chdir=>d)
         filename = "\xA4\xA2".force_encoding("euc-jp")
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename)
       EOS
       assert_separately(%w[-EUTF-8:EUC-JP], <<-'EOS', :chdir=>d)
@@ -151,7 +151,7 @@ class TestDir_M17N < Test::Unit::TestCase
         File.open(filename1, "w") {}
         File.open(filename2, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename1)
         assert_include(ents, filename2)
       EOS
@@ -159,7 +159,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename1 = "\u2661" # WHITE HEART SUIT which is not representable in EUC-JP
         filename2 = "\xA4\xA2".force_encoding("euc-jp") # HIRAGANA LETTER A in EUC-JP
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         assert_include(ents, filename1)
         assert_include(ents, filename2)
       EOS
@@ -183,7 +183,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xA4\xA2".force_encoding("euc-jp")
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         ents.each {|e| e.force_encoding("ASCII-8BIT") }
         if /darwin/ =~ RUBY_PLATFORM
           filename = filename.encode("utf-8")
@@ -200,7 +200,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xA4\xA2".force_encoding("euc-jp")
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         if /darwin/ =~ RUBY_PLATFORM
           filename = filename.encode("utf-8").force_encoding("euc-jp")
         end
@@ -210,14 +210,14 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xA4\xA2".force_encoding('ASCII-8BIT')
         win_expected_filename = filename.encode(Encoding.find("filesystem"), "euc-jp") rescue "?"
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         unless ents.include?(filename)
           case RUBY_PLATFORM
           when /darwin/
             filename = filename.encode("utf-8", "euc-jp").b
           when /mswin|mingw/
             if ents.include?(win_expected_filename.b)
-              ents = Dir.entries(".", {:encoding => Encoding.find("filesystem")})
+              ents = Dir.entries(".", :encoding => Encoding.find("filesystem"))
               filename = win_expected_filename
             end
           end
@@ -246,7 +246,7 @@ class TestDir_M17N < Test::Unit::TestCase
         filename = "\xA4\xA2".force_encoding("euc-jp")
         File.open(filename, "w") {}
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         if /darwin/ =~ RUBY_PLATFORM
           filename = filename.encode("utf-8", "euc-jp").force_encoding("euc-jp")
         end
@@ -255,7 +255,7 @@ class TestDir_M17N < Test::Unit::TestCase
       assert_separately(%w[-EEUC-JP:UTF-8], <<-'EOS', :chdir=>d)
         filename = "\u3042"
         opts = {:encoding => Encoding.default_external} if /mswin|mingw/ =~ RUBY_PLATFORM
-        ents = Dir.entries(".", opts)
+        ents = Dir.entries(".", **(opts||{}))
         if /darwin/ =~ RUBY_PLATFORM
           filename = filename.force_encoding("euc-jp")
         end
@@ -420,7 +420,7 @@ class TestDir_M17N < Test::Unit::TestCase
       else
         orig.each {|o| o.force_encoding(enc) }
       end
-      ents = Dir.entries(".", opts).reject {|n| /\A\./ =~ n}
+      ents = Dir.entries(".", **(opts||{})).reject {|n| /\A\./ =~ n}
       ents.sort!
       PP.assert_equal(orig, ents, bug7267)
     }

test/ruby/test_econv.rb

@@ -3,7 +3,12 @@ require 'test/unit'
 
 class TestEncodingConverter < Test::Unit::TestCase
   def check_ec(edst, esrc, eres, dst, src, ec, off, len, opts=nil)
-    res = ec.primitive_convert(src, dst, off, len, opts)
+    case opts
+    when Hash
+      res = ec.primitive_convert(src, dst, off, len, **opts)
+    else
+      res = ec.primitive_convert(src, dst, off, len, opts)
+    end
     assert_equal([edst.b, esrc.b, eres],
                  [dst.b,  src.b,  res])
   end

test/ruby/test_exception.rb

@@ -1223,6 +1223,14 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     assert_equal("#{__FILE__}:#{__LINE__-1}: warning: test warning\n", warning[0])
     assert_raise(ArgumentError) {warn("test warning", uplevel: -1)}
     assert_in_out_err(["-e", "warn 'ok', uplevel: 1"], '', [], /warning:/)
+    warning = capture_warning_warn {warn("test warning", {uplevel: 0})}
+    assert_equal("#{__FILE__}:#{__LINE__-1}: warning: The last argument is used as the keyword parameter\n", warning[0])
+    assert_match(/warning: for method defined here|warning: test warning/, warning[1])
+    warning = capture_warning_warn {warn("test warning", **{uplevel: 0})}
+    assert_equal("#{__FILE__}:#{__LINE__-1}: warning: test warning\n", warning[0])
+    warning = capture_warning_warn {warn("test warning", {uplevel: 0}, **{})}
+    assert_equal("test warning\n{:uplevel=>0}\n", warning[0])
+    assert_raise(ArgumentError) {warn("test warning", foo: 1)}
   end
 
   def test_warning_warn_invalid_argument

test/ruby/test_io.rb

@@ -423,7 +423,7 @@ class TestIO < Test::Unit::TestCase
     path = t.path
     t.close!
     assert_raise(Errno::ENOENT, "[ruby-dev:33072]") do
-      File.read(path, nil, nil, {})
+      File.read(path, nil, nil, **{})
     end
   end
 
@@ -2489,15 +2489,15 @@ class TestIO < Test::Unit::TestCase
       assert_equal(["foo\n", "bar\n", "baz\n"], a)
 
       a = []
-      IO.foreach(t.path, {:mode => "r" }) {|x| a << x }
+      IO.foreach(t.path, :mode => "r") {|x| a << x }
       assert_equal(["foo\n", "bar\n", "baz\n"], a)
 
       a = []
-      IO.foreach(t.path, {:open_args => [] }) {|x| a << x }
+      IO.foreach(t.path, :open_args => []) {|x| a << x }
       assert_equal(["foo\n", "bar\n", "baz\n"], a)
 
       a = []
-      IO.foreach(t.path, {:open_args => ["r"] }) {|x| a << x }
+      IO.foreach(t.path, :open_args => ["r"]) {|x| a << x }
       assert_equal(["foo\n", "bar\n", "baz\n"], a)
 
       a = []
@@ -3119,7 +3119,9 @@ __END__
       assert_equal(1, File.write(path, "f", 0, encoding: "UTF-8"))
       assert_equal("ff", File.read(path))
       assert_raise(TypeError) {
-        File.write(path, "foo", Object.new => Object.new)
+        assert_warn(/The last argument is split into positional and keyword parameters/) do
+          File.write(path, "foo", Object.new => Object.new)
+        end
       }
     end
   end

test/ruby/test_io_m17n.rb

@@ -23,7 +23,8 @@ class TestIO_M17N < Test::Unit::TestCase
 
   def pipe(*args, wp, rp)
     re, we = nil, nil
-    r, w = IO.pipe(*args)
+    kw = args.last.is_a?(Hash) ? args.pop : {}
+    r, w = IO.pipe(*args, **kw)
     rt = Thread.new do
       begin
         rp.call(r)

test/ruby/test_literal.rb

@@ -189,7 +189,7 @@ class TestRubyLiteral < Test::Unit::TestCase
     def test_debug_frozen_string
       src = 'n = 1; _="foo#{n ? "-#{n}" : ""}"'; f = "test.rb"; n = 1
       opt = {frozen_string_literal: true, debug_frozen_string_literal: true}
-      str = RubyVM::InstructionSequence.compile(src, f, f, n, opt).eval
+      str = RubyVM::InstructionSequence.compile(src, f, f, n, **opt).eval
       assert_equal("foo-1", str)
       assert_predicate(str, :frozen?)
       assert_raise_with_message(FrozenError, /created at #{Regexp.quote(f)}:#{n}/) {
@@ -200,7 +200,7 @@ class TestRubyLiteral < Test::Unit::TestCase
     def test_debug_frozen_string_in_array_literal
       src = '["foo"]'; f = "test.rb"; n = 1
       opt = {frozen_string_literal: true, debug_frozen_string_literal: true}
-      ary = RubyVM::InstructionSequence.compile(src, f, f, n, opt).eval
+      ary = RubyVM::InstructionSequence.compile(src, f, f, n, **opt).eval
       assert_equal("foo", ary.first)
       assert_predicate(ary.first, :frozen?)
       assert_raise_with_message(FrozenError, /created at #{Regexp.quote(f)}:#{n}/) {

test/ruby/test_numeric.rb

@@ -230,7 +230,8 @@ class TestNumeric < Test::Unit::TestCase
   end
 
   def assert_step(expected, (from, *args), inf: false)
-    enum = from.step(*args)
+    kw = args.last.is_a?(Hash) ? args.pop : {}
+    enum = from.step(*args, **kw)
     size = enum.size
     xsize = expected.size
 
@@ -239,7 +240,7 @@ class TestNumeric < Test::Unit::TestCase
       assert_send [size, :>, 0], "step size: +infinity"
 
       a = []
-      from.step(*args) { |x| a << x; break if a.size == xsize }
+      from.step(*args, **kw) { |x| a << x; break if a.size == xsize }
       assert_equal expected, a, "step"
 
       a = []
@@ -249,7 +250,7 @@ class TestNumeric < Test::Unit::TestCase
       assert_equal expected.size, size, "step size"
 
       a = []
-      from.step(*args) { |x| a << x }
+      from.step(*args, **kw) { |x| a << x }
       assert_equal expected, a, "step"
 
       a = []

test/ruby/test_string.rb

@@ -17,8 +17,8 @@ class TestString < Test::Unit::TestCase
     super
   end
 
-  def S(*args)
+  def S(*args, **kw)
-    @cls.new(*args)
+    @cls.new(*args, **kw)
   end
 
   def test_s_new