The value (#<SB-C::REF :LEAF #1=#<SB-KERNEL:CONSTANT :VALUE = {1006C2A0B3}> {1006C2A2A3}> #<SB-C::REF :LEAF #1# {1006C2A123}>) is not of type (AND ATOM (NOT NULL))

[Paul F. Dietz]

(lambda (op) (funcall (case op (equal '=) (t '=)) 1 2))

===>

The value
  (#<SB-C::REF
     :LEAF #1=#<SB-KERNEL:CONSTANT
                :VALUE = {1006C2A0B3}> {1006C2A2A3}>
   #<SB-C::REF :LEAF #1# {1006C2A123}>)

is not of type
  (AND ATOM (NOT NULL))
[...]
  0: (SB-C::ENSURE-LVAR-FUN-FORM #<SB-C::LVAR 1 {1006C2A623}> SB-C::THING T)
  1: ((SB-C:DEFTRANSFORM SB-KERNEL:%COERCE-CALLABLE-TO-FUN) #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME SB-KERNEL:%COERCE-CALLABLE-TO-FUN :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :..
  2: (SB-C::IR1-TRANSFORM #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME SB-KERNEL:%COERCE-CALLABLE-TO-FUN :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :DEFINED-TYPE #1# :WHERE-FROM :DECL..
  3: (SB-C::IR1-OPTIMIZE-COMBINATION #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME SB-KERNEL:%COERCE-CALLABLE-TO-FUN :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :DEFINED-TYPE #1# :WHERE..
 [...]

[Stas Boukarev (stassats)]

In bbb18bb338e15f7f3dee572aef2968b693031889.