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From: tml@hemuli.tik.vtt.fi (Tor Lillqvist)
Newsgroups: comp.windows.x
Subject: Infinite recursion bug in Xt
Message-ID: <5043@hemuli.tik.vtt.fi>
Date: 3 Aug 90 08:08:24 GMT
Organization: Technical Research Centre of Finland, Laboratory for Information Processing (VTT/TIK)
Lines: 35

I ran across something that seems like an infinite recursion bug in
Xt:

Look at Intrinsic.c:_XtWindowedAncestor:

    if (object == NULL) {
	String params = XtName(object);
	Cardinal num_params = 1;
	XtAppErrorMsg(XtWidgetToApplicationContext(object),
		      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
		   "noWidgetAncestor", "windowedAncestor", XtCXtToolkitError,
		   "Object \"%s\" does not have windowed ancestor",
		   &params, &num_params);
    }


Now look at Display.c:XtWidgetToApplicationContext:

	return _XtGetPerDisplay(XtDisplayOfObject(w))->appContext;
				^^^^^^^^^^^^^^^^^^^^

And then IntrinsicI.h:

#define XtDisplayOfObject(object) \
    ((XtIsWidget(object) ? (object) : _XtWindowedAncestor(object)) \
				      ^^^^^^^^^^^^^^^^^^^^^^^^^^^
     ->core.screen->display)


As yo notice, you _XtWindowedAncestor and XtWidgetToApplicationContext
will call each other infinitely...  I got a (huge) core dump when playing
with xtex.
-- 
Tor Lillqvist,
working, but not speaking, for the Technical Research Centre of Finland