hu.dwim.zlib broke; broken operation-done-p

[Faré]

On Tue, Jan 30, 2018 at 5:01 PM, Attila Lendvai <attila at lendvai.name> wrote:
> if you issue the following (available in quicklisp):
>
> (asdf:load-system :hu.dwim.zlib)
>
> then for the first time it should generate a lisp file, which then gets
> compiled and loaded.
>
> issuing it for the second time shouldn't do anything, but since some
> revisions it regenerates the lisp file every time.
>
> the relevant code is somewhere around here:
>
> https://github.com/cffi/cffi/blob/master/src/c2ffi/asdf.lisp#L135
>
> i tried to trace the INPUT-FILES, OUTPUT-FILES, PERFORM,
> OPERATION-DONE-P methods, but i don't see anything wrong.
>
> one unusual thing is that the output of GENERATE-LISP-OP goes into the
> src/ directory, not to the usual fasl output dir. same applies to
> GENERATE-SPEC-OP.
>
> any ideas how to debug this? or what to look at?
>
I can reproduce the issue using asdf 3.3.1.3 from master (the tag
hadn't been pushed, so I pushed it, but the code was already there).

(plan-actions (nth-value 1 (operate 'load-op :hu.dwim.zlib)))

starts with:
((#<CFFI/C2FFI::GENERATE-SPEC-OP > . #<CFFI/C2FFI:C2FFI-FILE
"hu.dwim.zlib" "c2ffi-spec" "zlib.h">)
 (#<CFFI/C2FFI::GENERATE-LISP-OP > . #<CFFI/C2FFI:C2FFI-FILE
"hu.dwim.zlib" "c2ffi-spec" "zlib.h">)
 (#<COMPILE-OP > . #<CFFI/C2FFI:C2FFI-FILE "hu.dwim.zlib" "c2ffi-spec"
"zlib.h">) (#<LOAD-OP > . #<CFFI/C2FFI:C2FFI-FILE "hu.dwim.zlib"
"c2ffi-spec" "zlib.h">)

So somehow the first action above is considered not done. I suppose
it's a bug in c2ffi.

Looking at the c2ffi source, I don't see anything obviously wrong,
though you shouldn't the (the (not null) (find-system ...)) since
find-system will error out for you if the system is not found (to
avoid error, add optional argument nil, as in find-class).

My theory is that that you're failing to re-generate the .spec when
it's present, even though your dependencies say it will be
re-generated. Therefore, ASDF decides that it's out-of-date and must
be re-generated again the next time over, etc. In other words, you lie
to ASDF, and ASDF punishes you right back.

To make ASDF happy, you might instead want to have two disjoint
operation modes, one to generate the spec files, and one to use it.
Normal use mode wouldn't try to generate the file, but instead bork
with a useful error message telling you how to generate it and submit
it upstream.

Another strategy to make ASDF happy would be to detect whether the
file exists as part of input-files and output-files. If it exists,
it's in input-files and not output-files; if not, it's in output-files
and not input-files. There's something I don't like about this
strategy, but it might work (somehow I can't swear it won't bite you
back somehow at some point).

Good luck!

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