The following method call improperly captures the result of "baz" and passes it and the result of "bar" as the 2nd and 3rd arguments:

def foo(a, b, c, d)
  p [a, b, c, d]
end
def bar = [1, 2]
def baz = 6
foo(0, *(baz; bar), 3)

This should output [0, 1, 2, 3] but instead it outputs [0, 6, [1, 2], 3].

It affects both 9.4 and 10, in both interpreter and JIT, so it appears to be a bug in IR compilation.

This causes most net-imap tests to fail because of the following line:

https://github.com/ruby/net-imap/blob/e58aff64d55dda4215fa0cfd7f4d1ea7b9ca51ba/lib/net/imap/response_parser.rb#L804

The TaggedResponse gets initialized with bogus values, which causes the imap client to terminate early because the response is not valid.