Re: Guile debugger workgroup?

[Maxim Cournoyer]

Hi Attila,

Attila Lendvai <attila@lendvai.name> writes:

> coming from common lisp (and SBCL in particular), i think the lowest
> hanging fruit in the guile debugging experience is making sure that
> backtraces are not cut short when printed.
>
> i tried multiple ways to configure the printer to acquire more info,
> but it didn't react to anything i tried:
>
> (setenv "COLUMNS" "300")
> (debug-set! width 160)
> (debug-set! depth 1000)
>
> this is regularly causing me frustration when all i need to make
> progress is in the cut off part of the backtrace, and the code in
> question is in a part of the codebase that i can't easily change to
> add some good old printf's.

Thanks for reminding me of this problem.  I thought the following might
do it:

--8<---------------cut here---------------start------------->8---
modified   doc/guix.texi
@@ -18263,6 +18263,10 @@ This data type represents the configuration of the 
Guix build daemon.
 @item @code{guix} (default: @var{guix})
 The Guix package to use.
 
+@item @code{backtrace-width} (default: @var{400})
+The character width at which backtraces of Guile processes launched by
+the Guix daemon should be truncated.
+
 @item @code{build-group} (default: @code{"guixbuild"})
 Name of the group for build user accounts.
 
modified   gnu/services/base.scm
@@ -187,6 +187,7 @@ (define-module (gnu services base)
             guix-configuration?
 
             guix-configuration-guix
+            guix-configuration-backtrace-width
             guix-configuration-build-group
             guix-configuration-build-accounts
             guix-configuration-authorize-key?
@@ -1634,6 +1635,8 @@ (define-record-type* <guix-configuration>
                     (default 0))
   (timeout          guix-configuration-timeout    ;integer
                     (default 0))
+  (backtrace-width  guix-configuration-backtrace-width ;integer
+                    (default 400))
   (log-compression  guix-configuration-log-compression
                     (default 'gzip))
   (discover?        guix-configuration-discover?
@@ -1701,7 +1704,7 @@ (define (guix-shepherd-service config)
     (guix build-group build-accounts authorize-key? authorized-keys
           use-substitutes? substitute-urls max-silent-time timeout
           log-compression discover? extra-options log-file
-          http-proxy tmpdir chroot-directories)
+          http-proxy tmpdir chroot-directories backtrace-width)
     (list (shepherd-service
            (documentation "Run the Guix daemon.")
            (provision '(guix-daemon))
@@ -1771,6 +1774,9 @@ (define discover?
                                         (list (string-append "TMPDIR=" tmpdir))
                                         '())
 
+                                 #$(string-append "COLUMNS=" (number->string
+                                                              backtrace-width))
+
                                  ;; Make sure we run in a UTF-8 locale so that
                                  ;; 'guix offload' correctly restores nars
                                  ;; that contain UTF-8 file names such as
--8<---------------cut here---------------end--------------->8---

But it doesn't seem to work :-(.

> which reminds me that a project-wide logging infrastructure would also
> greatly elevate the guix debugging experience.

I wouldn't be against having a logging system in Guix; there's a readily
available logging library part of guile-lib; see info '(guile-library)
loggig logger')

-- 
Thanks,
Maxim