[asdf-devel] asdf loading error error

[Faré]

On Sun, Feb 23, 2014 at 11:27 AM, Robert Goldman <rpgoldman at sift.net> wrote:
>> There's an error while reporting a warning (warning about your system
>> having a bad version string).
>> I suggest you add this method in system.lisp after defclass system:
>>  (defmethod builtin-system-p ((x null)) nil)
>> Does it help?
>>
>> Robert, do you want me to commit that?
>
> I'd like to understand this patch better before we push it.
>
> Why is it that having a method on NIL is right?  Doesn't this just mask a bug where we are incorrectly treating NIL as if it's a system designator?
>
> What's the cause for trying to ask if NIL is a built in system?  Presumably some system lookup returned NIL, right?  If so, why wasn't that trapped as an error?
>
In this case it's not so much a system designator than something
returned by (find-system name nil) in a case where it's acceptable.
The test that matters is in parse-defsystem.lisp function
normalize-version:
  (unless (builtin-system-p (find-component parent component))
which for backward compatibility (probably with old SBCL), declines to
warn about builtin systems that have badly formed version strings. But
in this case, the system doesn't exist, so find-system returns nil,
and builtin-system-p errors out instead of returning nil.

The warning message should NOT error out when the system doesn't
exist, and either you should put that unless under an (if-let (dep
(find-component parent component)) ...) or you should make
builtin-system-p accept nil as input (nil does not designate a
builtin-system).

Now, from Mark Evenson's explanation of how abcl-asdf is abusing the
version string, it seems that indeed, abcl should not be doing that —
at least, not unless and until we adopt some extensible
version-compatibility protocol, as has been discussed before, though
without a fully worked out proposal. Note that the strict "semantic
versioning" requirement of ASDF versions already existed in ASDF1, but
wasn't enforced, except backhandedly by hand/or ASDF3 saving
version-satisfies (and thus :version dependency-def) silently give
non-meaningful answers. ASDF2 started issuing warnings instead, which
is the right thing to do. Eventually, these warnings could be turned
into errors, after cleaning up quicklisp.

Mark: yes, abcl-asdf better avoid that route for now, unless you want
to first propose a patch to asdf. Please use a different slot
maven-version or some such.

—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org
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