[Chicken-janitors] #1465: get-keyword fails to operate correctly if keywords in first and second arguments come from different environments

[Chicken Trac]

#1465: get-keyword fails to operate correctly if keywords in first and second
arguments come from different environments
----------------------------+--------------------------------
 Reporter:  jrobbins        |                 Owner:
     Type:  defect          |                Status:  new
 Priority:  major           |             Milestone:  someday
Component:  core libraries  |               Version:  4.13.0
 Keywords:                  |  Estimated difficulty:  trivial
----------------------------+--------------------------------
 Run the following code in csi, and you'll get a failed assertion:

 {{{
 (define-syntax keyword-from-syntax (syntax-rules () ((_) #:k)))
 (assert (get-keyword (keyword-from-syntax) '(h i j #:k l)))
 }}}

 This should return {{{l}}}, but instead it returns {{{#f}}}. The bug
 occurs when a keywords from different environments are compared; the
 {{{#:k}}} from the syntax-rules is not being treated as equal to the
 {{{#:k}}} from the normal code for some reason.

 A working replacement (and the replacement I use in my code) could be as
 follows:

 {{{
 (define (get-keyword kw args . default)
   (let (
     (tail (memq kw args))
   )
     (if (and tail (not (null? (cdr tail))))
       (cadr tail)
       (if (null? default)
         #f
         ((car default))
       )
     )
   )
 )
 }}}

--
Ticket URL: <https://bugs.call-cc.org/ticket/1465>
CHICKEN Scheme <https://www.call-cc.org/>
CHICKEN Scheme is a compiler for the Scheme programming language.