Do not use VM stack for splat arg on cfunc

On the cfunc methods, if a splat argument is given, all array elements
are expanded on the VM stack and it can cause SystemStackError.
The idea to avoid it is making a hidden array to contain all parameters
and use this array as an argv.

This patch is reviesed version of https://github.com/ruby/ruby/pull/6816
The main change is all changes are closed around calling cfunc logic.

Fixes [Bug #4040]

Co-authored-by: Jeremy Evans <code@jeremyevans.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/vm_core.h b/vm_core.h
index 4f6e07d818..1f5c56aa17 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -297,7 +297,7 @@ struct rb_calling_info {
     VALUE block_handler;
     VALUE recv;
     int argc;
-    int kw_splat;
+    bool kw_splat;
 };
 
 struct rb_execution_context_struct;