FIND and similar functions throw compile time errors on short improper lists

[Paul F. Dietz]

These forms might come up in macroexpansion and be dead, so no error should be thrown.

(compile nil '(lambda (c) (let ((x '(1 2 . 3))) (when (proper-list-p x (find c x))))))

==>

The value
  3
is not of type
  LIST
   [Condition of type TYPE-ERROR]

Restarts:
 0: [RETRY] Retry SLIME REPL evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT] abort thread (#<THREAD "new-repl-thread" RUNNING {102BF57813}>)

Backtrace:
  0: (LENGTH (1 2 . 3))
  1: ((SB-C:DEFTRANSFORM FIND) #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME FIND :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :DEFINED-TYPE #1# :WHERE-FROM :DECLARED :KIND :GLOBAL-FUNCT..
  2: (SB-C::IR1-OPTIMIZE-COMBINATION #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME FIND :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :DEFINED-TYPE #1# :WHERE-FROM :DECLARED :KIND :GLOBAL..
  3: (SB-C::IR1-OPTIMIZE #<SB-C:COMPONENT :NAME (LAMBDA (C)) {102C2D9F63}> NIL)
  4: (SB-C::IR1-OPTIMIZE-UNTIL-DONE #<SB-C:COMPONENT :NAME (LAMBDA (C)) {102C2D9F63}>)
  5: (SB-C::IR1-OPTIMIZE-PHASE-1 #<SB-C:COMPONENT :NAME (LAMBDA (C)) {102C2D9F63}>)
[...]

Similar failures occur with POSITION, POSITION-IF, and likely others.

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

Correction: just position, not position-if.