Support keyword splatting nil

nil is treated similarly to the empty hash in this case, passing
no keywords and not calling any conversion methods.

Fixes [Bug #20064]

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>

1 files changed, 7 insertions, 5 deletions

diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index d81a121c1f..63567e8f87 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -2668,8 +2668,10 @@ static inline VALUE
 vm_caller_setup_keyword_hash(const struct rb_callinfo *ci, VALUE keyword_hash)
 {
     if (UNLIKELY(!RB_TYPE_P(keyword_hash, T_HASH))) {
-        /* Convert a non-hash keyword splat to a new hash */
-        keyword_hash = rb_hash_dup(rb_to_hash_type(keyword_hash));
+        if (keyword_hash != Qnil) {
+            /* Convert a non-hash keyword splat to a new hash */
+            keyword_hash = rb_hash_dup(rb_to_hash_type(keyword_hash));
+        }
     }
     else if (!IS_ARGS_KW_SPLAT_MUT(ci)) {
         /* Convert a hash keyword splat to a new hash unless
@@ -2699,7 +2701,7 @@ CALLER_SETUP_ARG(struct rb_control_frame_struct *restrict cfp,
             if (vm_caller_setup_arg_splat(cfp, calling, ary, max_args)) return;
 
             // put kw
-            if (!RHASH_EMPTY_P(kwh)) {
+            if (kwh != Qnil && !RHASH_EMPTY_P(kwh)) {
                 if (UNLIKELY(calling->heap_argv)) {
                     rb_ary_push(calling->heap_argv, kwh);
                     ((struct RHash *)kwh)->basic.flags |= RHASH_PASS_AS_KEYWORDS;
@@ -2770,7 +2772,7 @@ check_keyword:
         VM_ASSERT(calling->kw_splat == 1);
         VALUE kwh = vm_caller_setup_keyword_hash(ci, cfp->sp[-1]);
 
-        if (RHASH_EMPTY_P(kwh)) {
+        if (kwh == Qnil || RHASH_EMPTY_P(kwh)) {
             cfp->sp--;
             calling->argc--;
             calling->kw_splat = 0;
@@ -3596,7 +3598,7 @@ vm_call_cfunc_only_splat_kw(rb_execution_context_t *ec, rb_control_frame_t *reg_
     RB_DEBUG_COUNTER_INC(ccf_cfunc_only_splat_kw);
     VALUE keyword_hash = reg_cfp->sp[-1];
 
-    if (RB_TYPE_P(keyword_hash, T_HASH) && RHASH_EMPTY_P(keyword_hash)) {
+    if (keyword_hash == Qnil || (RB_TYPE_P(keyword_hash, T_HASH) && RHASH_EMPTY_P(keyword_hash))) {
         return vm_call_cfunc_array_argv(ec, reg_cfp, calling, 1, 0);
     }