Loop in constraint propagation with notinlined flet

[Paul F. Dietz]

(lambda (a b c)
  (prog1
      (case a
        ((3188) c)
        (t 132240))
    (loop repeat 3
          sum (progn
                (tagbody
                   (flet ((%f7 (&optional (f7-2 0) (f7-3 81) &key (key1 (go 5)))
                            (declare (ignore f7-2 f7-3 key1))
                            675155407991333))
                     (declare (notinline %f7))
                     (%f7 a 18354665292)
                     228559833622833108)
                 5)
                b))))

==> compiler loops, apparently in constraint propagation

x86-64, "2.4.1.120-1f0732114"