Subject: eq? problem at -O2 since Guile 3.0.5
From: Marius Bakke <[email-masked]>
To: [email-masked]
Date: Tue, 11 May 2021 22:49:19 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi!

I haven't been able to make a reproducer for this, but for illustrative
purposes, here is a code snippet that fails with -O2 on Guile 3.0.5 and
later (excerpt from GNU Shepherd):

  (define (run-command socket-file action service args)
    "Perform ACTION with ARGS on SERVICE, and display the result.  Connect to
  the daemon via SOCKET-FILE."
    (with-system-error-handling
     (let ((sock    (open-connection socket-file))
           (action* (if (and (eq? action 'detailed-status)
                             (memq service '(root shepherd)))
                        'status
                        action)))
       ;; Send the command.
       (write-command (shepherd-command action* service #:arguments args)
                      sock)

https://git.savannah.gnu.org/cgit/shepherd.git/tree/modules/shepherd/scripts/herd.scm#n124

At -O2, (eq? action 'detailed-status) evaluates to true no matter what
symbol ACTION holds.

Interestingly, adding (pk action*) between LET and WRITE-COMMAND gives
the expected result and mitigates the problem(!).

There are other issues that can be observed by running the Shepherd test
suite (i.e. make -j4 check).  With -O1 all pass.