The function SB-KERNEL:SINGLE-FLOAT-SIGN is undefined.

[Paul F. Dietz]

(defun f375 (p1)
  (declare (type (eql -96088.234) p1))
  (float-sign
   (the single-float
        (labels ((%f () (the real p1))) (%f))
        )))

(f375 -96088.234) ==>

The function SB-KERNEL:SINGLE-FLOAT-SIGN is undefined.
   [Condition of type UNDEFINED-FUNCTION]

Restarts:
 0: [CONTINUE] Retry calling SB-KERNEL:SINGLE-FLOAT-SIGN.
 1: [USE-VALUE] Call specified function.
 2: [RETURN-VALUE] Return specified values.
 3: [RETURN-NOTHING] Return zero values.
 4: [ABORT] Exit debugger, returning to top level.

Backtrace:
  0: ("undefined function" -96088.234)
  1: (SB-INT:SIMPLE-EVAL-IN-LEXENV (F375 -96088.234) #<NULL-LEXENV>)
  2: (EVAL (F375 -96088.234))
[...]

[Paul F. Dietz (paul-f-dietz)]

(defun f375a (f)
  (declare (type (function () (eql 1.0)) f))
  (float-sign (the single-float (flet ((%f () (funcall f))) (%f)))))

(f375a 1.0) ==> same error

[Paul F. Dietz (paul-f-dietz)]

Rather, (f375a (lambda () 1.0))

[Stas Boukarev (stassats)]

cc2eeb58834f4babf95411e6e63338e14379fed8