Tcl Source Code

I have committed the attached patch that eliminates an unnecessary (I think!) numLevels++ in TclSubstTokens. Note that there is a call to TclEvalEx, which in turn calls Tcl_EvalObjv, which does the numLevel management.

If I'm wrong ... please revert.

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no, they count levels of recursion
in substitution, before command procedure
invocation is reached.

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Understood: these count parser recursion levels, not evaluation recursion levels.

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Add

    proc {} args {}

to that last demo script to avoid
issues irrelevant to the subject.

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If this management of numLevels is removed,
the following test script will no longer
work correctly:

    interp recursionlimit {} 100
    testevalex [string repeat \[ 200][string repeat \] 200]

The limit won't catch the evaluation.

The implication is that an arbitrary number of
nested calls to TclEvalEx can happen on the C stack
without any protection.

Unless things change even more under the hood,
we still need those lines managing numLevels
in TclSubstTokens.

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Ooops ... now I did, thx.

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Did you restore the call to TclResetCancellation?

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Keeping open for review at leisure

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Patch reverted.

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hmmm, they're passing, but only
because they've been revised.

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Revision 1.40 of tclParse.c was
the first to acquire those numLevel
manipulations, allegedly to fix
Bug 1115904.  Tests parse-19.[1-4]
were added to test the fix, so if
they're still passing, things should 
be ok.

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Remark that this is related to "Kill TEOVi" (outdated Patch #1904111).

All evals now go through TEOV, which manages the numLevel. Before this change direct callers of TEOVi (bypassing TEOV) had to manage the numLevel.

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need a cvs history check for
when the code was added, and
what bug, if any, it was fixing
at the time.

File Added - 284571: numlevels.patch