[Chicken-janitors] #1475: (scrutinizer) Types for global variables are not refined by predicates

[Chicken Trac]

#1475: (scrutinizer) Types for global variables are not refined by predicates
-------------------------+-----------------------------
 Reporter:  megane       |                 Owner:
     Type:  defect       |                Status:  new
 Priority:  major        |             Milestone:  5.1
Component:  scrutinizer  |               Version:  5.0
 Keywords:               |  Estimated difficulty:  easy
-------------------------+-----------------------------
 {{{
 (: g1 (list-of fixnum))
 (define g1 '())
 ;; Aliased global gets refined
 (let ((a g1))
   (compiler-typecase a ((list-of fixnum) 1))
   (if (null? a)
       (compiler-typecase a (null 1))
       (compiler-typecase a ((not null) 1))))

 (: g2 (list-of fixnum))
 (define g2 '())
 (if (null? g2)
     (compiler-typecase g2 (null 1)) ;; <- error
     (compiler-typecase g2 ((pair fixnum (list-of fixnum)) 1)))

 ;; $ csc -O3 globals.scm
 ;;
 ;; Error: at toplevel:
 ;;   (globals.scm:13) no clause applies in `compiler-typecase' for
 expression of type `(list-of fixnum)':
 ;;     null
 }}}

 I don't think this is an issue of non-local mutation (e.g. from other
 threads). You should use mutexes or some other measures to prevent
 mutation while, you're working on a global.

--
Ticket URL: <https://bugs.call-cc.org/ticket/1475>
CHICKEN Scheme <https://www.call-cc.org/>
CHICKEN Scheme is a compiler for the Scheme programming language.