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Date: Sun, 28 Jun 2015 15:06:16 +0200
From: "piranna@...il.com" <piranna@...il.com>
To: musl@...ts.openwall.com
Subject: Re: Fwd: Link problems with static node-canvas

> That's normal, for example I've taken one symbol from `nm -u` and
> checked it just with `nm` and this symbol is properly defined:
>
> % nm /local/lib/libjpeg.a | fgrep jpeg_alloc_huff_table
>          U jpeg_alloc_huff_table
> 000000b0 T jpeg_alloc_huff_table
>          U jpeg_alloc_huff_table
>          U jpeg_alloc_huff_table
>
> Just other object files inside library are referencing this symbol and
> have source object file with this symbol as dependency and ld inserts
> it into final executable/shared object. That's why `nm` reports them as
> undefined.

Yeah, this makes sense since .a is just an archive file like zip, so
there's no info regarding available symbols and this is delegated to
the link process...

This gave an idea and searching for "nm symbol is undefined" I got to
https://blog.flameeyes.eu/2010/09/your-worst-enemy-undefined-symbols#gsc.tab=0
that talks about the '-Wl,--no-undefined' option, that allows to show
an error when there are undefined symbols also in dynamic libraries.
This gave me a lot of entries regarding some harm-less virtual
destructors on node-canvas and some entries for node and v8 namespaces
(that should be filled by Node.js binary after doing dlopen()) and
some other entries for FreeType and libJpeg. After searching for the
files that had them... I found that gyp was not compiling them, so
they were not available on link stage (Doh! :-( ). I supposed this
kind of things would show a better warning, so I didn't though about
it, and also the tests of node-canvas didn't gave any problem... After
adding them, these entries dissappeared leaving only the virtual
destructors, node and v8 ones, and some of the examples that were
failing due to FreeType dependencies now work when compiled with glibc
:-)

After that I compiled it with musl and got another symbol not found
(_ZN2v87Isolate17CollectAllGarbageEPKc) that's strange because it
should be provided by Node.js, but maybe I'm having a version conflict
here, I'm going to investigate it.


-- 
"Si quieres viajar alrededor del mundo y ser invitado a hablar en un
monton de sitios diferentes, simplemente escribe un sistema operativo
Unix."
– Linus Tordvals, creador del sistema operativo Linux

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