Convert keyword argument to required positional hash argument for Class#new, Method#call, UnboundMethod#bind_call

Also add keyword argument separation warnings for Class#new and Method#call.

To allow for keyword argument to required positional hash converstion in
cfuncs, add a vm frame flag indicating the cfunc was called with an empty
keyword hash (which was removed before calling the cfunc).  The cfunc can
check this frame flag and add back an empty hash if it is passing its
arguments to another Ruby method.  Add rb_empty_keyword_given_p function
for checking if called with an empty keyword hash, and
rb_add_empty_keyword for adding back an empty hash to argv.

All of this empty keyword argument support is only for 2.7.  It will be
removed in 3.0 as Ruby 3 will not convert empty keyword arguments to
required positional hash arguments.  Comment all of the relevent code
to make it obvious this is expected to be removed.

Add rb_funcallv_kw as an public C-API function, just like rb_funcallv
but with a keyword flag.  This is used by rb_obj_call_init (internals
of Class#new).  This also required expected call_type enum with
CALL_FCALL_KW, similar to the recent addition of CALL_PUBLIC_KW.

Add rb_vm_call_kw as a internal function, used by call_method_data
(internals of Method#call and UnboundMethod#bind_call). Add tests
for UnboundMethod#bind_call keyword handling.

1 files changed, 10 insertions, 2 deletions

diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index c04c620b44..a83e3a952a 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -2206,8 +2206,9 @@ vm_method_cfunc_entry(const rb_callable_method_entry_t *me)
     return UNALIGNED_MEMBER_PTR(me->def, body.cfunc);
 }
 
+/* -- Remove empty_kw_splat In 3.0 -- */
 static VALUE
-vm_call_cfunc_with_frame(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, struct rb_calling_info *calling, const struct rb_call_info *ci, struct rb_call_cache *cc)
+vm_call_cfunc_with_frame(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, struct rb_calling_info *calling, const struct rb_call_info *ci, struct rb_call_cache *cc, int empty_kw_splat)
 {
     VALUE val;
     const rb_callable_method_entry_t *me = cc->me;
@@ -2223,6 +2224,9 @@ vm_call_cfunc_with_frame(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp
     if (UNLIKELY(calling->kw_splat)) {
         frame_type |= VM_FRAME_FLAG_CFRAME_KW;
     }
+    else if (UNLIKELY(empty_kw_splat)) {
+        frame_type |= VM_FRAME_FLAG_CFRAME_EMPTY_KW;
+    }
 
     RUBY_DTRACE_CMETHOD_ENTRY_HOOK(ec, me->owner, me->def->original_id);
     EXEC_EVENT_HOOK(ec, RUBY_EVENT_C_CALL, recv, me->def->original_id, ci->mid, me->owner, Qundef);
@@ -2249,10 +2253,14 @@ vm_call_cfunc_with_frame(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp
 static VALUE
 vm_call_cfunc(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, struct rb_calling_info *calling, const struct rb_call_info *ci, struct rb_call_cache *cc)
 {
+    int empty_kw_splat = calling->kw_splat;
     RB_DEBUG_COUNTER_INC(ccf_cfunc);
 
     CALLER_SETUP_ARG(reg_cfp, calling, ci);
-    return vm_call_cfunc_with_frame(ec, reg_cfp, calling, ci, cc);
+    if (empty_kw_splat && calling->kw_splat) {
+        empty_kw_splat = 0;
+    }
+    return vm_call_cfunc_with_frame(ec, reg_cfp, calling, ci, cc, empty_kw_splat);
 }
 
 static VALUE