+;;; Note: this function gets called by the compiler (as of 1.0.17.x,
+;;; in MAYBE-INLINE-SYNTACTIC-CLOSURE), and so although ANSI says
+;;; we're allowed to return NIL here freely, it seems plausible that
+;;; small changes to the circumstances under which this function
+;;; returns non-NIL might have subtle consequences on the compiler.
+;;; So it might be desirable to have the compiler not rely on this
+;;; function, eventually.