#4267 Redefining object constructor after error causes SIGSEGV

[Andy Goth]

oo::class create foo {constructor {} {error x}}
foo new
oo::define foo {constructor {} {}}
foo new

The first invocation of [foo new] fails with error "x". The second invocation of [foo new] crashes the Tcl interpreter.

Observed using Pat Thoyts's tclkit-gui-86b1.exe (x86 Windows) and using a self-compiled Tcl 8.6b1 on Linux. Here's the backtrace on the latter:

#0 0x031e22e8 in ?? ()
#1 0x00b90d44 in TclOOInvokeContext (clientData=0x998b070, interp=0x998a8e0,
objc=2, objv=0x998b04c)
at /home/users/td26063/build/tcl8.6b1/generic/tclOOCall.c:303
#2 0x00b8d681 in TclNRNewObjectInstance (interp=0x998a8e0, cls=0x99c6728,
nameStr=0x0, nsNameStr=0x0, objc=2, objv=0x998b04c, skip=2,
objectPtr=0x99bd1c4)
at /home/users/td26063/build/tcl8.6b1/generic/tclOO.c:1394
#3 0x00b8f346 in TclOO_Class_New (clientData=0x0, interp=0x998a8e0,
context=0x998b058, objc=2, objv=0x998b04c)
at /home/users/td26063/build/tcl8.6b1/generic/tclOOBasic.c:238
#4 0x00b90d44 in TclOOInvokeContext (clientData=0x998b058, interp=0x998a8e0,
objc=2, objv=0x998b04c)
at /home/users/td26063/build/tcl8.6b1/generic/tclOOCall.c:303
#5 0x00b8e86f in TclOOObjectCmdCore (oPtr=0x99c6540, interp=0x998a8e0,
objc=2, objv=0x998b04c, flags=1, startCls=0x0)
at /home/users/td26063/build/tcl8.6b1/generic/tclOO.c:2110
#6 0x00b8e4c7 in PublicNRObjectCmd (clientData=0x99c6540, interp=0x998a8e0,
objc=2, objv=0x998b04c)
at /home/users/td26063/build/tcl8.6b1/generic/tclOO.c:1951
#7 0x00ab0f8c in NRRunObjProc (data=0x99adbcc, interp=0x998a8e0, result=0)
at /home/users/td26063/build/tcl8.6b1/generic/tclBasic.c:4303
#8 0x00ab0d7d in TclNRRunCallbacks (interp=0x998a8e0, result=0,
rootPtr=0x999b680, tebcCall=1)
at /home/users/td26063/build/tcl8.6b1/generic/tclBasic.c:4241
#9 0x00b08b76 in TclExecuteByteCode (interp=0x998a8e0, codePtr=0x99c6bd0)
at /home/users/td26063/build/tcl8.6b1/generic/tclExecute.c:2813
#10 0x00ab1020 in NRCallTEBC (data=0x99a9484, interp=0x998a8e0, result=0)
at /home/users/td26063/build/tcl8.6b1/generic/tclBasic.c:4325
#11 0x00ab0d7d in TclNRRunCallbacks (interp=0x998a8e0, result=0, rootPtr=0x0,
tebcCall=0) at /home/users/td26063/build/tcl8.6b1/generic/tclBasic.c:4241
#12 0x00ab2c9f in TclEvalObjEx (interp=0x998a8e0, objPtr=0x999e548,
flags=131072, invoker=0x0, word=0)
at /home/users/td26063/build/tcl8.6b1/generic/tclBasic.c:5717
#13 0x00ab2c40 in Tcl_EvalObjEx (interp=0x998a8e0, objPtr=0x31e22e8,
flags=131072) at /home/users/td26063/build/tcl8.6b1/generic/tclBasic.c:5698
#14 0x00b1dcb7 in Tcl_RecordAndEvalObj (interp=0x998a8e0, cmdPtr=0x99adc58,
flags=131072)
at /home/users/td26063/build/tcl8.6b1/generic/tclHistory.c:161
#15 0x00b429ae in Tcl_Main (argc=-1, argv=0xbfe56b38,
appInitProc=0x804868b <Tcl_AppInit>)
at /home/users/td26063/build/tcl8.6b1/generic/tclMain.c:468
#16 0x0804867e in main (argc=1, argv=0xbfe56b34)
at /home/users/td26063/build/tcl8.6b1/unix/tclAppInit.c:87

[Andy Goth]

Oops, sorry about the bug title. It should have been "Redefining object constructor after error causes SIGSEGV".

[Donal K. Fellows]

The error isn't necessary. The problem also occurs if you create and delete an object.

(It's caused by a failure to clear a cache upon setting a constructor. Destructors were similarly broken.)

[Donal K. Fellows]

Fixed in HEAD and in the stand-alone TclOO code.