#213 ItclContext size too small

[Jan Nijtmans]

When compiling Itcl 3.4 using Tcl 8.5 and running it with Tcl 8.6, then running the test cases:

Tests began at Fri Jul 08 08:52:28 CEST 2011
basic.test

==== basic-5.6a variable accesses variables within namespace FAILED
==== Contents of test case:

list [catch {test_globals::getval g1} msg] $msg

---- Result was:
0 {}
---- Result should have been (exact matching):
0 global1
==== basic-5.6a FAILED
.........
==== namespace-1.4 create an object in another namespace FAILED
==== Contents of test case:

namespace eval test_ns_2 {
list [Counter c] [c ++] [c ++] [c ++] [c ++]
}

---- Result was:
c 1 2 2 2
---- Result should have been (exact matching):
c 1 2 4 8
==== namespace-1.4 FAILED

protection.test
scope.test

Tests ended at Fri Jul 08 08:52:57 CEST 2011
all.tcl: Total 400 Passed 362 Skipped 0 Failed 38

The reason for this is that the ItclContext structure is too small
in this situation: The reason: ItclContext uses ItclCallFrame as
one of its structure members, but in Tcl8.6 this member has
an extra field added. This field overwrites the compiledLocals
field whenever the (Tcl_Push|Pop)CallFrame function pair
is used on this CallFrame.

Solution: Use Itcl_CallFrame (which maps to Tcl_CallFrame)
in stead of TclCallFrame, which is modified to contain those
extra (dummy) fields, exactly to prevent this very problem.

Here is the patch which fixes this.

[Jan Nijtmans]

proposed fix

[Don Porter]

Any tips how I can reproduce this?

[Jan Nijtmans]

>Any tips how I can reproduce this?

Since your checkin [cc1cf10c58] form yesterday, this
bug is fixed as well. But I don't agree with simply
copying structure definitions from tclXxx.h to
itclXxx.h.

So, reproducing goes as follows: revert [cc1cf10c58]
and then apply this patch. Much simpler..... It
fixes the same thing.

I already created this patch yesterday, but put
it in SF today, without checking your cuncurrent work.

Regards,
Jan Nijtmans

[Don Porter]

aha! That makes more sense. Will look it over.

[Don Porter]

Committed what appears to be correct.
It tests ok for me. Please confirm.

[Jan Nijtmans]

Yes, this is how it always should have be. With the tip of core-8.4-branch and
any later Tcl version, this should always work fine.

However, this depends on Tcl 8.4 since [541d313d64] (2010-07-25). If you
compile Itcl 3.4 against released Tcl 8.4.19 and running it against
Tcl 8.5/8.6, the same crash will still happen.

That's why I would recommend to bring out Tcl 8.4.20 before Itcl 3.4.1,
and simply state that Tcl 3.4.1 must be compiled against Tcl 8.4.20+
in order to work with all later Tcl versions.

But it's up to you. We can also provde the Itcl_CallFrame replacement
when compiling against Tcl 8.4 only, then we are always on the
safe side.

[Jan Nijtmans]

This final patch (itcl-safest.patch) makes it work with
all earlier Tcl 8.4 versions as well, not only the tip of
the core-8-4-branch, that's what I would do.

[Jan Nijtmans]

make it work against Tcl 8.4.19 and earlier

[Jan Nijtmans]

Oops, wrong cut-paste. Here is the correct one!