[Chicken-janitors] #575: Extended lambda list syntax with default values isn't checked properly

[Chicken Trac]

#575: Extended lambda list syntax with default values isn't checked properly
----------------------------------------------------+-----------------------
 Reporter:  sjamaan                                 |       Owner:  felix
     Type:  defect                                  |      Status:  new  
 Priority:  minor                                   |   Milestone:  4.8.0
Component:  expander                                |     Version:  4.6.x
 Keywords:  DSSSL lambda list, keywords, optionals  |  
----------------------------------------------------+-----------------------
 When using a default value with an optional argument, you get a strange
 error message that there's an error in your LET syntax, and when you do
 the same with a keyword argument, Chicken segfaults.

 The reason is there's a missing check in {{{##sys#expand-extended-lambda-
 list}}}'s final {{{cond}}} clause; it implicitly assumes that a 2-element
 list after {{{#!key}}} or {{{#!optional}}} always has a symbol as its car.
 The attached patch contains a simple fix and regression test.

 {{{
 CHICKEN
 (c)2008-2010 The Chicken Team
 (c)2000-2007 Felix L. Winkelmann
 Version 4.6.0
 netbsd-unix-gnu-x86-64 [ 64bit manyargs dload ptables ]
 compiled 2011-01-21 on langly (NetBSD)

 #;1> (define (foo #!optional 0) 1)

 Error: invalid lambda list syntax: (#!optional 0)

         Call history:

         <syntax>          (define (foo #!optional 0) 1)
         <syntax>          (##core#set! foo (##core#lambda (#!optional 0)
 1))
         <syntax>          (##core#lambda (#!optional 0) 1)      <--
 #;1> (define (foo #!optional (0 0)) 1)

 Error: during expansion of (let12 ...) - in `let' - symbol expected: (let
 ((0 (optional tmp 0))) 1)

         Call history:

         <syntax>          (define (foo #!optional (0 0)) 1)
         <syntax>          (##core#set! foo (##core#lambda (#!optional (0
 0)) 1))
         <syntax>          (##core#lambda (#!optional (0 0)) 1)  <--
 #;1> (define (foo #!key 0) 1)

 Error: invalid lambda list syntax: (#!key 0)

         Call history:

         <syntax>          (define (foo #!key 0) 1)
         <syntax>          (##core#set! foo (##core#lambda (#!key 0) 1))
         <syntax>          (##core#lambda (#!key 0) 1)   <--
 #;1> (define (foo #!key (0 0)) 1)
 zsh: segmentation fault  csi
 }}}

-- 
Ticket URL: <http://bugs.call-cc.org/ticket/575>
Chicken Scheme <http://www.call-with-current-continuation.org/>
Chicken Scheme is a compiler for the Scheme programming language.