Can't SET-INFO-VALUE on PCL-internal function (malformed code)

[Paul F. Dietz]

(compile nil '(lambda () #'(sb-pcl::fast-method)))

==>

Can't SET-INFO-VALUE on PCL-internal function
   [Condition of type SIMPLE-ERROR]
[...]
Backtrace:
  0: (SB-INT:SET-INFO-VALUE (SB-PCL::FAST-METHOD) 3 NIL)
  1: (SB-C::IR1-FINALIZE #<SB-C:COMPONENT :NAME (LAMBDA NIL) {102AC6AAD3}>)
  2: (SB-C::IR1-PHASES #<SB-C:COMPONENT :NAME (LAMBDA NIL) {102AC6AAD3}>)
  3: (SB-C::COMPILE-COMPONENT #<SB-C:COMPONENT :NAME (LAMBDA NIL) {102AC6AAD3}>)
[...]