Generics with setters have <applicable-struct-with-setter> layout

* libguile/goops.c (scm_sys_set_object_setter_x): Remove.  Instead, we
  use slot-set! of 'setter.
  (scm_i_define_class_for_vtable): Move lower in the file, and fold in
  scm_make_extended_class_from_symbol and make_class_from_symbol.
  Properly handle applicable structs with setters.
  (scm_class_applicable_struct_with_setter_class): New private capture.
  (scm_sys_bless_applicable_struct_vtables_x): Rename to take two
  arguments, and bless the second argument as an applicable struct with
  setter vtable.
  (scm_sys_goops_early_init): Capture setter classes.

* libguile/deprecated.c (SPEC_OF, CPL_OF): Access slots by name, not by
  index.
  (applicablep, more_specificp): Adapt to use CPL_OF.
  (scm_find_method): Access "methods" slot by name.

* libguile/procs.c (scm_setter): Remove special case for generics; if
  it's a setter, it will be a normal applicable struct.
* module/oop/goops.scm (<applicable-struct-with-setter-class>)
  (<applicable-struct-with-setter>): New classes.
  (<generic-with-setter>): Now an instance of the setter metaclass and a
  child of the setter class, so that the "setter" slot ends up in the
  right place.
  (<accessor>, <extended-generic-with-setter>, <extended-accessor>): Be
  instances of the setter metaclass.
  (<method>, <accessor-method>): Move definitions farther down.
  (make): Use slot-set! when initializing setters here.
  (initialize): Likewise for <applicable-struct-with-setter>.  Remove
  specialization for <generic-with-setter>.

module/oop/goops.scm

@@ -51,8 +51,8 @@
             <procedure> <primitive-generic>
 
             ;; Applicable structs.
-            <applicable-struct-class>
-            <applicable-struct>
+            <applicable-struct-class> <applicable-struct-with-setter-class>
+            <applicable-struct> <applicable-struct-with-setter>
             <generic> <extended-generic>
             <generic-with-setter> <extended-generic-with-setter>
             <accessor> <extended-accessor>
@@ -434,21 +434,20 @@
 
 ;; Applicables and their classes.
 (define-standard-class <procedure-class> (<class>))
-(define-standard-class <applicable-struct-class> (<procedure-class>))
-(%bless-applicable-struct-vtable! <applicable-struct-class>)
-(define-standard-class <method> (<object>)
-  generic-function
-  specializers
-  procedure
-  formals
-  body
-  make-procedure)
-(define-standard-class <accessor-method> (<method>)
-  (slot-definition #:init-keyword #:slot-definition))
+(define-standard-class <applicable-struct-class>
+  (<procedure-class>))
+(define-standard-class <applicable-struct-with-setter-class>
+  (<applicable-struct-class>))
+(%bless-applicable-struct-vtables! <applicable-struct-class>
+                                   <applicable-struct-with-setter-class>)
+
 (define-standard-class <applicable> (<top>))
 (define-standard-class <applicable-struct> (<object> <applicable>)
   #:metaclass <applicable-struct-class>
   procedure)
+(define-standard-class <applicable-struct-with-setter> (<applicable-struct>)
+  #:metaclass <applicable-struct-with-setter-class>
+  setter)
 (define-standard-class <generic> (<applicable-struct>)
   #:metaclass <applicable-struct-class>
   methods
@@ -460,22 +459,33 @@
   #:metaclass <applicable-struct-class>
   (extends #:init-value ()))
 (%bless-pure-generic-vtable! <extended-generic>)
-(define-standard-class <generic-with-setter> (<generic>)
-  #:metaclass <applicable-struct-class>
-  setter)
+(define-standard-class <generic-with-setter> (<generic>
+                                              <applicable-struct-with-setter>)
+  #:metaclass <applicable-struct-with-setter-class>)
 (%bless-pure-generic-vtable! <generic-with-setter>)
 (define-standard-class <accessor> (<generic-with-setter>)
-  #:metaclass <applicable-struct-class>)
+  #:metaclass <applicable-struct-with-setter-class>)
 (%bless-pure-generic-vtable! <accessor>)
 (define-standard-class <extended-generic-with-setter> (<extended-generic>
                                                        <generic-with-setter>)
-  #:metaclass <applicable-struct-class>)
+  #:metaclass <applicable-struct-with-setter-class>)
 (%bless-pure-generic-vtable! <extended-generic-with-setter>)
 (define-standard-class <extended-accessor> (<accessor>
                                             <extended-generic-with-setter>)
-  #:metaclass <applicable-struct-class>)
+  #:metaclass <applicable-struct-with-setter-class>)
 (%bless-pure-generic-vtable! <extended-accessor>)
 
+;; Methods
+(define-standard-class <method> (<object>)
+  generic-function
+  specializers
+  procedure
+  formals
+  body
+  make-procedure)
+(define-standard-class <accessor-method> (<method>)
+  (slot-definition #:init-keyword #:slot-definition))
+
 ;; Primitive types classes
 (define-standard-class <boolean> (<top>))
 (define-standard-class <char> (<top>))
@@ -534,7 +544,7 @@
       (when (eq? class <accessor>)
         (let ((setter (get-keyword #:setter args #f)))
           (when setter
-            (%set-object-setter! z setter))))
+            (slot-set! z 'setter setter))))
       z))
    (else
     (let ((z (%allocate-instance class args)))
@@ -2160,6 +2170,11 @@
   (next-method)
   (initialize-object-procedure applicable-struct initargs))
 
+(define-method (initialize (applicable-struct <applicable-struct-with-setter>)
+                           initargs)
+  (next-method)
+  (slot-set! applicable-struct 'setter (get-keyword #:setter initargs #f)))
+
 (define-method (initialize (generic <generic>) initargs)
   (let ((previous-definition (get-keyword #:default initargs #f))
 	(name (get-keyword #:name initargs #f)))
@@ -2172,10 +2187,6 @@
 	(set-procedure-property! generic 'name name))
     (invalidate-method-cache! generic)))
 
-(define-method (initialize (gws <generic-with-setter>) initargs)
-  (next-method)
-  (%set-object-setter! gws (get-keyword #:setter initargs #f)))
-
 (define-method (initialize (eg <extended-generic>) initargs)
   (next-method)
   (slot-set! eg 'extends (get-keyword #:extends initargs '())))