The SBCL version
(macroexpand-1 '(defstruct spoint (x y)))
(PROGN (SB-KERNEL:WITH-SINGLE-PACKAGE-LOCKED-ERROR (:SYMBOL 'SPOINT "defining ~A as a structure")) (SB-KERNEL::%DEFSTRUCT '# '#(# #) (SB-C:SOURCE-LOCATION)) (EVAL-WHEN (:COMPILE-TOPLEVEL :LOAD-TOPLEVEL :EXECUTE) (SB-KERNEL::%COMPILER-DEFSTRUCT '# '#(# #))) (DECLAIM (FTYPE (SB-INT:SFUNCTION (&KEY (:X T)) SPOINT) MAKE-SPOINT)) (DEFUN MAKE-SPOINT (&KEY ((:X #:DUM947) Y)) (SB-KERNEL::%MAKE-STRUCTURE-INSTANCE-MACRO # '((:SLOT T . 1)) #:DUM947)) (LOCALLY (DECLARE (NOTINLINE SB-KERNEL:FIND-CLASSOID)) (SETF (SB-KERNEL::STRUCTURE-CLASSOID-CONSTRUCTOR (SB-KERNEL:FIND-CLASSOID 'SPOINT)) #'MAKE-SPOINT)) 'SPOINT)
(macroexpand-1 '(defclass point () (x y)))
(PROGN (EVAL-WHEN (:COMPILE-TOPLEVEL) (SB-PCL::%COMPILER-DEFCLASS 'POINT 'NIL 'NIL '(Y X))) (EVAL-WHEN (:LOAD-TOPLEVEL :EXECUTE) (LET () (SB-PCL::LOAD-DEFCLASS 'POINT 'STANDARD-CLASS 'NIL (LIST (LIST* :NAME 'X :READERS 'NIL :WRITERS 'NIL :INITARGS 'NIL 'NIL) (LIST* :NAME 'Y :READERS 'NIL :WRITERS 'NIL :INITARGS 'NIL 'NIL)) (LIST :DIRECT-DEFAULT-INITARGS NIL) 'NIL 'NIL '(Y X) (SB-C:SOURCE-LOCATION) 'NIL))))
The Allegro CL version
(macroexpand-1 '(defstruct spoint (x y)))
(PROGN (PROGN (EVAL-WHEN (COMPILE) (EXCL::CHECK-LOCK-DEFINITIONS-COMPILE-TIME 'SPOINT :TYPE 'DEFSTRUCT (SYSTEM:CE-GET 'SPOINT 'EXCL::%STRUCTURE-DEFINITION))) (EVAL-WHEN (LOAD EVAL) (EXCL::CHECK-LOCK-DEF-DEFSTRUCT 'SPOINT)) (RECORD-SOURCE-FILE 'SPOINT :TYPE :TYPE)) (PROGN (EVAL-WHEN (COMPILE) (PUSH 'SPOINT-X EXCL::.FUNCTIONS-DEFINED.)) (RECORD-SOURCE-FILE 'SPOINT-X) (SETF (SYMBOL-FUNCTION 'SPOINT-X) (EXCL::GET-BUILT-IN-ACCESSOR 1))) (DEFSETF SPOINT-X EXCL::DEFSTRUCT-SLOT-DEFSETF-HANDLER 1) (DEFUN MAKE-SPOINT (&KEY (#:X Y)) (SYSTEM::NEW-STRUCT 'SPOINT #:X)) (DEFINE-COMPILER-MACRO MAKE-SPOINT (&WHOLE EXCL::WHOLE &REST REST) (LET ((EXCL::INITS #)) (IF EXCL::INITS (EXCL::BQ-LIST `LET* EXCL::INITS #) EXCL::WHOLE))) (EXCL::DEFINEF COPY-SPOINT (SYMBOL-FUNCTION 'COPY-STRUCTURE)) (EXCL::DEFINEF SPOINT-P (EXCL::GET-DD-PREDICATE-CLOSURE 'SPOINT)) (EVAL-WHEN (LOAD EVAL) (LET ((EXCL::NEW #)) (EXCL::COMPUTE-STRUCT-CPL EXCL::NEW) (EXCL::NOTIFY-CLOS-OF-NEW-STRUCTURE 'SPOINT EXCL::NEW) (EVAL-WHEN (LOAD EVAL) (SETF # EXCL::NEW)))) (EVAL-WHEN (COMPILE) (LET ((EXCL::OLD #) (EXCL::NEW #)) (SETF (EXCL::DD-INCLUDED-BY EXCL::NEW) (IF EXCL::OLD #)) (EXCL::COMPUTE-STRUCT-CPL EXCL::NEW) (EXCL::NOTIFY-CLOS-OF-NEW-STRUCTURE 'SPOINT EXCL::NEW SYSTEM:*COMPILATION-UNIT-ENVIRONMENT*) (SYSTEM:CE-PUTPROP 'SPOINT EXCL::NEW 'EXCL::%STRUCTURE-DEFINITION))) ...)
(macroexpand-1 '(defclass point () (x y)))
(PROGN NIL (EVAL-WHEN (COMPILE) (EXCL::CHECK-LOCK-DEFINITIONS-COMPILE-TIME 'POINT :TYPE 'DEFCLASS (FIND-CLASS 'POINT NIL))) (RECORD-SOURCE-FILE 'POINT :TYPE :TYPE) (EXCL::ENSURE-CLASS-1 'POINT :DIRECT-SUPERCLASSES 'NIL :DIRECT-SLOTS (LIST (LIST ':NAME 'X) (LIST ':NAME 'Y))))