properly check readpipe()'s argument list

readpipe() wasn't applying context to its argument list, resulting in
readpipe()'s context leaking in, and broken stack discipline when a list
expression was used.  Fixes [perl #4574].

(cherry picked from commit 397baf232086e0a9ad6f881a9614d3dbaea853fc)

1 files changed, 1 insertions, 0 deletions

diff --git a/op.c b/op.c
index 1517fa73b6..3e2e712b46 100644
--- a/op.c
+++ b/op.c
@@ -9610,6 +9610,7 @@ Perl_ck_backtick(pTHX_ OP *o)
     OP *newop = NULL;
     OP *sibl;
     PERL_ARGS_ASSERT_CK_BACKTICK;
+    o = ck_fun(o);
     /* qx and `` have a null pushmark; CORE::readpipe has only one kid. */
     if (o->op_flags & OPf_KIDS && (sibl = OpSIBLING(cUNOPo->op_first))
      && (gv = gv_override("readpipe",8)))