I don't have an answer for this one, but I've trimmed the issue down for
clarity. We have the following if-else_if-else:
881 if (FRAMEP (window))
882 {
883 f = XFRAME (window);
884 xpos = 0;
885 ypos = 0;
886 }
At conditional (12): "window & 7 == 4" taking false path
887 else if (WINDOWP (window))
888 {
889 CHECK_LIVE_WINDOW (window);
890 f = XFRAME (WINDOW_FRAME (XWINDOW (window)));
891
892 xpos = WINDOW_LEFT_EDGE_X (XWINDOW (window));
893 ypos = WINDOW_TOP_EDGE_Y (XWINDOW (window));
894 }
895 else
896 /* ??? Not really clean; should be CHECK_WINDOW_OR_FRAME,
897 but I don't want to make one now. */
At conditional (13): "window & 7 != 4" taking true path
At conditional (14): "0" taking false path
898 CHECK_WINDOW (window);
f, guaranteed to be NULL before this block, is assigned in the first two
cases but not in the third (which is tagged with a "huh?" comment). Later
f is used in a place Coverity claims requires non-nullity.