Make undef &foo remove call checkers

The fact that the call checker is stored in magic is an implementation
detail.  cv_undef does not free magic, so the call checker lives on.

If we were to move the parameter prototype into magic internally, we
would not want undef to stop clearing it.  To me, the current situa-
tion with call checkers is similar.

2 files changed, 11 insertions, 1 deletions

diff --git a/ext/XS-APItest/t/call_checker.t b/ext/XS-APItest/t/call_checker.t
index 429cea6b9b..b01323a75e 100644
--- a/ext/XS-APItest/t/call_checker.t
+++ b/ext/XS-APItest/t/call_checker.t
@@ -1,6 +1,6 @@
 use warnings;
 use strict;
-use Test::More tests => 67;
+use Test::More tests => 70;
 
 use XS::APItest;
 
@@ -169,4 +169,13 @@ is $@, "";
 is_deeply $foo_got, [ qw(a b), qw(a b c) ];
 is $foo_ret, "z";
 
+cv_set_call_checker_lists(\&foo);
+undef &foo;
+$foo_got = undef;
+eval 'sub foo($@) { $foo_got = [ @_ ]; return "z"; }
+      $foo_ret = foo(@b, @c);';
+is $@, "";
+is_deeply $foo_got, [ 2, qw(a b c) ], 'undef clears call checkers';
+is $foo_ret, "z";
+
 1;
diff --git a/pad.c b/pad.c
index 352c5f9ef0..71d5296b46 100644
--- a/pad.c
+++ b/pad.c
@@ -375,6 +375,7 @@ Perl_cv_undef(pTHX_ CV *cv)
     else if (slabbed) Perl_warn(aTHX_ "Slab leaked from cv %p", cv);
 #endif
     SvPOK_off(MUTABLE_SV(cv));		/* forget prototype */
+    sv_unmagic((SV *)cv, PERL_MAGIC_checkcall);
     CvGV_set(cv, NULL);
 
     /* This statement and the subsequence if block was pad_undef().  */