I've found and fixed two bugs in the reference implementation currently
at http://srfi.schemers.org/srfi-99/srfi-99.sls .

First one:

Ikarus Scheme version 0.0.4-rc1+ (revision 1865, build 2009-10-21)
Copyright (c) 2006-2009 Abdulaziz Ghuloum

> (load "srfi-99.sls")
> (import (srfi :99 records))
> (define-record-type point #T #T (x) (y))
Exception trapped by debugger.
 Condition components:
   1. &assertion
   2. &who: map
   3. &message: "not a proper list"
   4. &irritants: ()
[t] Trace. [r] Reraise exception. [c] Continue. [q] Quit. [?] Help.
>> t
CALL FRAMES:
FRAME 0:
 [0] (map (lambda (fspec field-spec) (cond ((symbol? fspec) (list 'immutable fspec (string->symbol (string-append type-name-string "-" (symbol->string fspec))))) ((not (pair? fspec)) (complain)) ((not (list? fspec)) (complain)) ((not (for-all symbol? fspec)) (complain)) ((null? (cdr fspec)) (list 'mutable (car fspec) (string->symbol (string-append type-name-string "-" (symbol->string (car fspec)))) (string->symbol (string-append type-name-string "-" (symbol->string (car fspec)) "-set!")))) ((null? (cddr fspec)) (list 'immutable (car fspec) (syntax-car (syntax-cdr field-spec)))) ((null? (cdddr fspec)) (list 'mutable (car fspec) (syntax-car (syntax-cdr field-spec)) (syntax-car (syntax-cdr (syntax-cdr field-spec))))) (else (complain)))) fspecs (syntax->list #'field-specs))
     operator: #<procedure map>
     operands: (#<procedure> ((x) (y)) (#<syntax (x)> . #<syntax ((y))>))
>>

After fixing the above one by modifying syntax->list (see the below
patch), I found the second one:

> (load "srfi-99.sls")
> (import (srfi :99 records))
> (define-record-type point #T #T (x) (y))
Unhandled exception
 Condition components:
   1. &message: "invalid expression"
   2. &syntax:
       form: #<syntax #f>
       subform: #f
   3. &trace: #<syntax #<syntax #f>>
>

The bug with this one is doing datum->syntax on syntax objects.  I fixed
it by modifying frob (see the below patch).

--- srfi-99.sls	2009-11-06 15:11:20.000000000 -0800
+++ srfi-99.sls--Derick	2009-11-06 15:09:05.000000000 -0800
@@ -223,8 +223,10 @@
                    (cons (frob (car x)) (frob (cdr x))))
                   ((vector? x)
                    (vector-map frob x))
+                  ((symbol? x)
+                   (datum->syntax tname x))
                   (else
-                   (datum->syntax tname x))))
+                   x)))

           #`(#,(frob #'define-record-type-helper)
              #,(frob tname)
@@ -258,9 +260,7 @@
       (define (syntax->list x)
         (syntax-case x ()
          (()
-          x)
-         ((x0)
-          x)
+          '())
          ((x0 . x1)
           (cons #'x0 (syntax->list #'x1)))))

--
: Derick
----------------------------------------------------------------