From 8a3e7f08b85a9a21077c420b6fa76f56899e90ee Mon Sep 17 00:00:00 2001
From: Matt Valentine-House <matt@eightbitraptor.com>
Date: Wed, 17 Jan 2024 16:44:58 +0000
Subject: [PATCH] [PRISM] Fix case splat with no predicate

---
 prism_compile.c                 |  5 +++--
 test/ruby/test_compile_prism.rb | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/prism_compile.c b/prism_compile.c
index 43ac0af160..2d1dd99388 100644
--- a/prism_compile.c
+++ b/prism_compile.c
@@ -3514,10 +3514,11 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
                 pm_node_t *condition_node = when_node->conditions.nodes[i];
 
                 if (PM_NODE_TYPE_P(condition_node, PM_SPLAT_NODE)) {
+                    int checkmatch_type = has_predicate ? VM_CHECKMATCH_TYPE_CASE : VM_CHECKMATCH_TYPE_WHEN;
                     ADD_INSN (ret, &dummy_line_node, dup);
                     PM_COMPILE_NOT_POPPED(condition_node);
-                    ADD_INSN1(ret, &dummy_line_node, splatarray, Qfalse);
-                    ADD_INSN1(ret, &dummy_line_node, checkmatch, INT2FIX(VM_CHECKMATCH_TYPE_CASE | VM_CHECKMATCH_ARRAY));
+                    ADD_INSN1(ret, &dummy_line_node, checkmatch,
+                              INT2FIX(checkmatch_type | VM_CHECKMATCH_ARRAY));
                 }
                 else {
                     PM_COMPILE_NOT_POPPED(condition_node);
diff --git a/test/ruby/test_compile_prism.rb b/test/ruby/test_compile_prism.rb
index f1274fccf5..0765a946a5 100644
--- a/test/ruby/test_compile_prism.rb
+++ b/test/ruby/test_compile_prism.rb
@@ -857,6 +857,17 @@ module Prism
         end
       RUBY
 
+      # Test splat in when
+      assert_prism_eval(<<~RUBY)
+        ary = [1, 2]
+        case 1
+        when :foo, *ary
+          :ok
+        else
+          :ng
+        end
+      RUBY
+
       # Test case without predicate
       assert_prism_eval(<<~RUBY)
         case
@@ -866,6 +877,16 @@ module Prism
           :ok
         end
       RUBY
+
+      # test splat with no predicate
+      assert_prism_eval(<<~RUBY)
+        case
+        when *[true]
+          :ok
+        else
+          :ng
+        end
+      RUBY
     end
 
     def test_ElseNode