Re: Debugger : Can't see local variables when stepping

Hi,

if you put `(break)` into the `let` form, you will be able to see the
variable (tested with SBCL 2.4.1 on Windows, the Roswell build).

(defun foo (var1)
  (let ((var2 (subseq var1 0 10)))
    (break)
    (dotimes (i 10 (fresh-line))
      (format t "~C" (char var2 i)))))

SLY:

break
   [Condition of type SIMPLE-CONDITION]

Restarts:
 0: [CONTINUE] Return from BREAK.
 1: [RETRY] Retry SLY mREPL evaluation request.
 2: [*ABORT] Return to SLY's top level.
 3: [ABORT] abort thread (#<THREAD "sly-channel-1-mrepl-remote-1" RUNNING
{1001160003}>)

Backtrace:
 0: (FOO "hello world")
      Locals:
        VAR1 = "hello world"
        VAR2 = "hello worl"

Hope that helps.

Martin

On Mon, Mar 18, 2024 at 10:25 AM Jérôme Radix <[email protected]>
wrote:

> Hello,
>
> When using the debugger, I can't figure out how to see the value of I and
> VAR2 in my little test code, even with (debug 3) optimization setting:
> (defun foo (var1)
>   (break)
>   (let ((var2 (subseq var1 0 10)))
>     (dotimes (i 10 (fresh-line))
>       (format t "~C" (char var2 i)))))
>
> (foo "Hello World")
>
> Here is the transcript of my session, on linux
> 5.15.146.1-microsoft-standard-WSL2:
>
> $ sbcl --no-sysinit --no-userinit
> This is SBCL 2.3.4, an implementation of ANSI Common Lisp.
> More information about SBCL is available at <http://www.sbcl.org/>.
>
> SBCL is free software, provided as is, with absolutely no warranty.
> It is mostly in the public domain; some portions are provided under
> BSD-style licenses.  See the CREDITS and COPYING files in the
> distribution for more information.
> * (declaim (optimize (debug 3)))
> NIL
> * (sb-ext:describe-compiler-policy)
>   Basic qualities:
> COMPILATION-SPEED = 1
> DEBUG = 3
> SAFETY = 1
> SPACE = 1
> SPEED = 1
> INHIBIT-WARNINGS = 1
>   Dependent qualities:
> SB-C::CHECK-CONSTANT-MODIFICATION = 1 -> 1 (maybe)
> SB-C::TYPE-CHECK = 1 -> 3 (full)
> SB-C::LET-CONVERSION = 1 -> 0 (off)
> SB-C:ALIEN-FUNCALL-SAVES-FP-AND-PC = 1 -> 3 (yes)
> SB-C:VERIFY-ARG-COUNT = 1 -> 3 (yes)
> SB-C::INSERT-DEBUG-CATCH = 1 -> 3 (yes)
> SB-C::RECOGNIZE-SELF-CALLS = 1 -> 0 (no)
> SB-C::FLOAT-ACCURACY = 1 -> 3 (full)
> SB-C:INSERT-STEP-CONDITIONS = 1 -> 3 (full)
> SB-C::COMPUTE-DEBUG-FUN = 1 -> 3 (yes)
> SB-C:STORE-SOURCE-FORM = 1 -> 3 (yes)
> SB-C::PRESERVE-SINGLE-USE-DEBUG-VARIABLES = 1 -> 3 (yes)
> SB-C::PRESERVE-CONSTANTS = 1 -> 0 (no)
> SB-C:INSERT-ARRAY-BOUNDS-CHECKS = 1 -> 3 (yes)
> SB-C::AREF-TRAPPING = 1 -> 0 (no)
> SB-C::STORE-XREF-DATA = 1 -> 3 (yes)
> SB-C:STORE-COVERAGE-DATA = 1 -> 0 (no)
> SB-C:INSTRUMENT-CONSING = 1 -> 1 (no)
> SB-C::STORE-CLOSURE-DEBUG-POINTER = 1 -> 0 (no)
> * (defun foo (var1)
>   (break)
>   (let ((var2 (subseq var1 0 10)))
>     (dotimes (i 10 (fresh-line))
>       (format t "~C" (char var2 i)))))
> FOO
> * (foo "Hello World")
>
> debugger invoked on a SIMPLE-CONDITION in thread
> #<THREAD tid=1590 "main thread" RUNNING {1001090003}>:
>   break
>
> Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.
>
> restarts (invokable by number or by possibly-abbreviated name):
>   0: [CONTINUE] Return from BREAK.
>   1: [ABORT   ] Exit debugger, returning to top level.
>
> (FOO "Hello World")
>    source: (BREAK)
> 0] start
> ; Evaluating call:
> ;   (SUBSEQ VAR1 0 10)
> ; With arguments:
> ;   "Hello World"
> ;   0
> ;   10
>
> 1] step
> ; (SUBSEQ VAR1 0 10) => "Hello Worl"
> ; Evaluating call:
> ;   (+ I 1)
> ; With unknown arguments
> H
> 0] step
> ; Evaluating call:
> ;   (+ I 1)
> ; With unknown arguments
> e
> 0] L
> VAR1  =  "Hello World"
>
> ==> I want to see the value of I and VAR2. What am I doing wrong ?
> I've tried several combinations of (declaim (optimize (debug 3) (space 0)
> (safety 3) (speed 0))) with no difference in behavior.
>
> Thanks for your help.
>
> Regards,
> Jérôme.
> _______________________________________________
> Sbcl-help mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/sbcl-help
>

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