[bug #31293] [HEAD] repl debugger "expected a positive width" error

[Mike Gran]

URL:
  <http://savannah.gnu.org/bugs/?31293>

                 Summary: [HEAD] repl debugger "expected a positive width"
error
                 Project: Guile
            Submitted by: mike121
            Submitted on: Sun 10 Oct 2010 04:03:41 PM GMT
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

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Details:

Hi-

It is pretty common when I'm trying to use the ",bt" or ",frame"
meta-commands that the meta-command aborts with an "expected a positive width"
error.  This means that somehow a zero width is being passed to the 'print'
subfunction in pretty-print.

To try to debug it, when a zero width was received by pretty-print's print
subfunction, I made it call a function "blammo" that just prints out a string
("MLG!") and then I continue the print as if the width were 1000 instead.

Here's a backtrace.  Unfortunately the functions that I happen to be in are
rather verbose getopt functions, so you'll have to ignore all of that.  And,
again, the "MLG!" strings indicate that a zero width was passed to
pretty-print's print proc.

In ice-9/pretty-print.scm:
    434:0  0 (blammo "expected a positive width" 0)
scheme@(guile-user) [2]> ,up

In ice-9/pretty-print.scm:
   385:10  1 (print (0 0 () "en_US.UTF-8" ((())) ((help # #) ...) . MLG! (#f
1 1 #f ("guile-ncurses-shell") . #<directory (guile-user) 84d3870>)) MLG! 0)
scheme@(guile-user) [2]> ,up

In ice-9/pretty-print.scm:
   391:12  2 (print (eval #<memoized (begin (if (if (#<variable …> MLG! (0
0 () "en_US.UTF-8" ((())) ((help (single-char #\h) (value #f)) (boldtext
(single-char #\D) (value #f)) (rebindkeypad (single-char #\K) (value #f))
(nonewlines (single-char #\L) (value #f)) (morespace (single-char #\O) (value
#f)) (restricted (single-char #\R) (value #f)) (tabsizelen (single-char #\T)
(value #t)) (version (single-char #\V) (value #f)) (const (single-char #\c)
(value #f)) (rebinddelete (single-char #\d) (value #f)) (nofollow (single-char
#\l) (value #f)) (preserve (single-char #\p) (value #f)) (quiet (single-char
#\q) (value #f)) (fill (single-char #\r) (value #t)) (tempfile (single-char
#\t) (value #f)) (view (single-char #\v) (value #f)) (nohelp (single-char #\x)
(value #f)) (suspend (single-char #\z) (value #f))) #f 1 1 #f
("guile-ncurses-shell") . #<directory (guile-user) 84d3870>)) MLG! 59)
scheme@(guile-user) [2]> ,up

In ice-9/r4rs.scm:
    174:4  3 (with-output-to-port #<variable 8d7a450 value: #<outpu…> MLG!
#<procedure 8b8ba20 at ice-9/pretty-print.scm:431:8 ()>)
scheme@(guile-user) [2]> ,up

In ice-9/pretty-print.scm:
    430:6  4 (truncated-print (eval #<memoized (begin (if (if (#…> MLG! (0
0 () "en_US.UTF-8" ((())) ((help (single-char #\h) (value #f)) (boldtext
(single-char #\D) (value #f)) (rebindkeypad (single-char #\K) (value #f))
(nonewlines (single-char #\L) (value #f)) (morespace (single-char #\O) (value
#f)) (restricted (single-char #\R) (value #f)) (tabsizelen (single-char #\T)
(value #t)) (version (single-char #\V) (value #f)) (const (single-char #\c)
(value #f)) (rebinddelete (single-char #\d) (value #f)) (nofollow (single-char
#\l) (value #f)) (preserve (single-char #\p) (value #f)) (quiet (single-char
#\q) (value #f)) (fill (single-char #\r) (value #t)) (tempfile (single-char
#\t) (value #f)) (view (single-char #\v) (value #f)) (nohelp (single-char #\x)
(value #f)) (suspend (single-char #\z) (value #f))) #f 1 1 #f
("guile-ncurses-shell") . #<directory (guile-user) 84d3870>)) ...)
scheme@(guile-user) [2]> ,up

In ice-9/r4rs.scm:
    174:4  5 (with-output-to-port #<variable 8d7a778 value: #<outpu…> MLG!
#<procedure 8b8ba80 at ice-9/format.scm:503:31 ()>)
scheme@(guile-user) [2]> ,up
           6 (call-with-output-string #<pro…>)
scheme@(guile-user) [2]> ,up

In ice-9/format.scm:
   502:29  7 (tilde-dispatch)
scheme@(guile-user) [2]> ,up

In ice-9/format.scm:
   832:12  8 (format:format-work "address@hidden:[~*~3_~;~3d~] ~v:@y~%" ("…" 
...))
scheme@(guile-user) [2]> ,up 

In ice-9/format.scm:
   197:25  9 (format:out #<output: standard output /dev/pts/5> "address@hidden" 
MLG!
("389:17" 6 6 72 (eval #<memoized (begin (if (if (#<variable 844d7e0 value:
#<procedure < (#:optional _ _ . _)>> (quote 0) <0>) (if (< <0> (- <1> (quote
1))) (eq? (string-ref (list-ref <2> <0>)) (quote #\+)) (quote #f)) (quote #f))
(begin (parse_line_column (string-drop (list-ref <2> <0>) (quote 1)) <8> <7>)
(set! <0> (+ <0> (quote 1)))) (quote #<unspecified>)) (if (if (#<variable
844d7e0 value: #<procedure < (#:optional _ _ . _)>> <0> <1>) (not (string=?
(list-ref <2> <0>) (quote "-"))) (quote #f)) (begin (stdin_pager)
(set_modified) (set! <0> (+ <0> (quote 1)))) (quote #<unspecified>)) (if
(#<variable 844d7e0 value: #<procedure < (#:optional _ _ . _)>> <0> <1>)
(open_buffer (list-ref <2> <0>) (quote #f)) (quote #<unspecified>))
(#<variable 84ac768 value: #<procedure format args>> (#<variable 83fb2f0
value: #<procedure current-error-port ()>>) (quote "2614: openfile = ~a~%")
(#<variable 8c1dcd8 value: #<procedure 8c21d08 at ice-9/eval.scm:378:13 ()>>))
(if (#<variable 83f7948 v…> MLG! (0 0 () "en_US.UTF-8" ((())) ((help
(single-char #\h) (value #f)) (boldtext (single-char #\D) (value #f))
(rebindkeypad (single-char #\K) (value #f)) (nonewlines (single-char #\L)
(value #f)) (morespace (single-char #\O) (value #f)) (restricted (single-char
#\R) (value #f)) (tabsizelen (single-char #\T) (value #t)) (version
(single-char #\V) (value #f)) (const (single-char #\c) (value #f))
(rebinddelete (single-char #\d) (value #f)) (nofollow (single-char #\l) (value
#f)) (preserve (single-char #\p) (value #f)) (quiet (single-char #\q) (value
#f)) (fill (single-char #\r) (value #t)) (tempfile (single-char #\t) (value
#f)) (view (single-char #\v) (value #f)) (nohelp (single-char #\x) (value #f))
(suspend (single-char #\z) (value #f))) #f 1 1 #f ("guile-ncurses-shell") .
#<directory (guile-user) 84d3870>))))
scheme@(guile-user) [2]> ,up

In system/repl/debug.scm:
    112:4 10 (print-frame #<frame 8eb8cf8 #<procedure eval (exp env…> ...)
scheme@(guile-user) [2]> ,up

In system/repl/debug.scm:
   134:12 11 (print-frames #(#<frame 8eb66b8 #<procedure memoize…> ...)
...)
scheme@(guile-user) [2]> ,up

In ice-9/r4rs.scm:
    174:4 12 (with-output-to-port #<variable 8d67248 value: #<outpu…> MLG!
#<procedure 8eb35e0 at system/repl/command.scm:486:0 ()>)
scheme@(guile-user) [2]> ,up

In system/repl/command.scm:
    486:0 13 (backtrace #<<repl> language: #<<language> name: scheme…>)
scheme@(guile-user) [2]> 





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