Tcl Source Code

The following script produces a segmentation fault:

<code><verbatim>
proc main {} {
    eval {
        try {
            lindex 5
        } on ok res {} 
    }
    puts $res
}
main
</verbatim></code>

The issue is: 

    [https://core.tcl.tk/tcl/artifact?udc=1&ln=4814&name=7abc6eff76e59d6d|tclCmdMZ.c:TryPostBody]
    extracts a variable name from a <code>Tcl_Obj</code>, causing a list
    internal representation to be created on that <code>Tcl_Obj</code>, and the
    original value of that <code>Tcl_Obj</code> to become the first item in the
    list, with a <code>refCount</code> of 1.

    On the next line, <code>Tcl_ObjSetVar2</code> is called, and
    [https://core.tcl.tk/tcl/artifact?udc=1&ln=738&name=f5bfe8cd3b7e5fd8|TclObjLookupVarEx]
    subsequently obtains that same <code>Tcl_Obj</code> from the cache of local
    variable names and frees that same list internal representation.

    At this point, <code>part1Ptr</code> is a reference to that freed
    <code>Tcl_Obj</code>.

closed in [e62a48e964]

Fixed in [4100488a3ca38abf].

See also related ticket [578155d5a1].

I'm for solution with TCL_OWN_OBJREF flag, which is a year ago merged in my own branches and it works there without any issue.