Clear method caches when unwinding local *foo=sub{}

local *foo=sub{} is done in two stages:

• First the local *foo localises the GP (the glob pointer, or list of
  slots), setting a flag on the GV.
• Then scalar assignment sees the flag on the GV on the LHS and loca-
  lises a single slot.

The slot localisation only stores on the savestack a pointer into the
GP struct and the old value.  There is no reference to the GV.

To restore a method properly, we have to have a reference to the GV
when the slot localisation is undone.

So in this commit I have added a new save type, SAVEt_GVSLOT.  It is
like SAVEt_GENERIC_SV, except it pushes the GV as well.  Currently
it is used only for CVs, but I will need it for HVs and maybe
AVs as well.

It is possible for the unwinding of the slot localisation to affect
only a GV other than the one that is pushed, if glob assignments have
taken place since the local *foo.  So we have to check whether the
pointer is inside the GP and use PL_sub_generation++ if it is not.

1 files changed, 0 insertions, 1 deletions

diff --git a/t/mro/method_caching.t b/t/mro/method_caching.t
index cbbd655f39..495e12fddc 100644
--- a/t/mro/method_caching.t
+++ b/t/mro/method_caching.t
@@ -37,7 +37,6 @@ my @testsubs = (
     sub { is(MCTest::Derived->foo(0), 5); },
     sub { { local *MCTest::Base::can = sub { "tomatoes" };
             MCTest::Derived->can(0); }
-          local $::TODO = " ";
           is(MCTest::Derived->can("isa"), \&UNIVERSAL::isa,
               'removing method when unwinding local *method=sub{}'); },
     sub { sub peas { "peas" }