[issue27945] Various segfaults with dict

[Duane Griffin]

Duane Griffin added the comment:

Apologies: compiling python with --with-pydebug all of these issues are reproducible on head after all. Furthermore while my patch fixes the reported crash it still crashes on exit:

Program received signal SIGSEGV, Segmentation fault.
0x0000000000437193 in visit_decref (op=0x7ffff68a4c98, data=0x0) at Modules/gcmodule.c:374
374	    if (PyObject_IS_GC(op)) {
(gdb) bt
#0  0x0000000000437193 in visit_decref (op=0x7ffff68a4c98, data=0x0) at Modules/gcmodule.c:374
#1  0x00000000004a9112 in tupletraverse (o=0x7ffff68a49f8, visit=0x43716d <visit_decref>, arg=0x0) at Objects/tupleobject.c:571
#2  0x000000000043690a in subtract_refs (containers=containers at entry=0x87cda0 <generations+64>) at Modules/gcmodule.c:399
#3  0x0000000000437ac3 in collect (generation=generation at entry=2, n_collected=n_collected at entry=0x7fffffffd838, n_uncollectable=n_uncollectable at entry=0x7fffffffd840, 
    nofail=nofail at entry=0) at Modules/gcmodule.c:956
#4  0x0000000000437f57 in collect_with_callback (generation=generation at entry=2) at Modules/gcmodule.c:1128
#5  0x00000000004383a6 in PyGC_Collect () at Modules/gcmodule.c:1592
#6  0x00000000004383cf in _PyGC_CollectIfEnabled () at Modules/gcmodule.c:1605
#7  0x0000000000420c76 in Py_FinalizeEx () at Python/pylifecycle.c:603
#8  0x000000000043682b in Py_Main (argc=argc at entry=2, argv=argv at entry=0x90d010) at Modules/main.c:798
#9  0x000000000041d153 in main (argc=2, argv=0x7fffffffdae8) at ./Programs/python.c:69

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<http://bugs.python.org/issue27945>
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