From 1edcfd610703fb6f773e8f31f88f8ca920bda1ac Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Sat, 14 Sep 2019 13:57:39 -0700
Subject: [PATCH] Issue a warning if invalid kw_splat is passed to *_kw
 function

This should only happen if the API is misused.  It's much better
to warn here and fix the problem, versus to try to debug TypeErrors
or segfaults later.
---
 vm_eval.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/vm_eval.c b/vm_eval.c
index b5d6dcca13..c896a44f79 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -255,6 +255,12 @@ add_empty_keyword(int *argc, const VALUE **argv, int *kw_splat)
             *kw_splat = rb_keyword_given_p();
         }
     }
+
+    if (*kw_splat && *argc > 0 && !RB_TYPE_P((*argv)[(*argc)-1], T_HASH)) {
+        rb_warn("Keyword flag passed calling internal method, but last entry is not a hash, unsetting keyword flag");
+        *kw_splat = 0;
+    }
+
     return 0;
 }