On Feb 10, 2013, at 1:27 AM, Ryan Schmidt <[email protected]> wrote:
>> You should check 'nm -m <binary>' to determine what it actually uses.
>> glibtool is just overzealous and assumes that it's safer to have the final
>> executable link against *everything*. We'd be doing ourselves a favor if
>> we forced a global post-destroot that just deleted ${prefix}/lib/*.la and
>> added a verification step that ensured every link was actually relevant.
>
> I haven't used the nm tool before and am not familiar with its output.
nm shows you what symbols are provided by the binary and which symbols it
needs. With 'nm -m' you will see more verbose output including where the
library resolves undefined symbols to. As a quick example of how much crud is
being linked which isn't needed, this first line shows what libpangocairo
actually needs:
~ $ nm -m /opt/local/lib/libpangocairo-1.0.dylib | grep 'undefined' | sed
's:^.*(from \(.*\)).*$:\1:' | sort -u
libSystem
libcairo
libfontconfig
libfreetype
libglib-2
libgobject-2
libpango-1
libpangoft2-1
And this is what it's linking against:
~ $ otool -L /opt/local/lib/libpangocairo-1.0.dylib
/opt/local/lib/libpangocairo-1.0.dylib:
/opt/local/lib/libpangocairo-1.0.0.dylib (compatibility version
3201.0.0, current version 3201.5.0)
/opt/local/lib/libpango-1.0.0.dylib (compatibility version 3201.0.0,
current version 3201.5.0)
/opt/local/lib/libcairo.2.dylib (compatibility version 11203.0.0,
current version 11203.12.0)
/opt/local/lib/libpixman-1.0.dylib (compatibility version 29.0.0,
current version 29.2.0)
/opt/local/lib/libpng15.15.dylib (compatibility version 30.0.0, current
version 30.0.0)
/opt/local/lib/libxcb-shm.0.dylib (compatibility version 1.0.0, current
version 1.0.0)
/opt/local/lib/libX11-xcb.1.dylib (compatibility version 2.0.0, current
version 2.0.0)
/opt/local/lib/libxcb-render.0.dylib (compatibility version 1.0.0,
current version 1.0.0)
/opt/local/lib/libXrender.1.dylib (compatibility version 5.0.0, current
version 5.0.0)
/opt/local/lib/libXext.6.dylib (compatibility version 11.0.0, current
version 11.0.0)
/opt/local/lib/libX11.6.dylib (compatibility version 10.0.0, current
version 10.0.0)
/opt/local/lib/libxcb.1.dylib (compatibility version 3.0.0, current
version 3.0.0)
/opt/local/lib/libXau.6.dylib (compatibility version 7.0.0, current
version 7.0.0)
/opt/local/lib/libXdmcp.6.dylib (compatibility version 7.0.0, current
version 7.0.0)
/opt/local/lib/libpangoft2-1.0.0.dylib (compatibility version 3201.0.0,
current version 3201.5.0)
/opt/local/lib/libgmodule-2.0.0.dylib (compatibility version 3401.0.0,
current version 3401.3.0)
/opt/local/lib/libharfbuzz.0.dylib (compatibility version 913.0.0,
current version 913.0.0)
/opt/local/lib/libgobject-2.0.0.dylib (compatibility version 3401.0.0,
current version 3401.3.0)
/opt/local/lib/libgthread-2.0.0.dylib (compatibility version 3401.0.0,
current version 3401.3.0)
/opt/local/lib/libffi.6.dylib (compatibility version 7.0.0, current
version 7.0.0)
/opt/local/lib/libglib-2.0.0.dylib (compatibility version 3401.0.0,
current version 3401.3.0)
/usr/lib/libresolv.9.dylib (compatibility version 1.0.0, current
version 41.1.0)
/opt/local/lib/libintl.8.dylib (compatibility version 10.0.0, current
version 10.2.0)
/opt/local/lib/libiconv.2.dylib (compatibility version 8.0.0, current
version 8.1.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current
version 125.2.11)
/opt/local/lib/libgraphite2.3.dylib (compatibility version 3.0.0,
current version 3.0.1)
/opt/local/lib/libicule.49.dylib (compatibility version 49.0.0, current
version 49.1.2)
/opt/local/lib/libicuuc.49.dylib (compatibility version 49.0.0, current
version 49.1.2)
/opt/local/lib/libicudata.49.dylib (compatibility version 49.0.0,
current version 49.1.2)
/opt/local/lib/libfontconfig.1.dylib (compatibility version 8.0.0,
current version 8.2.0)
/opt/local/lib/libfreetype.6.dylib (compatibility version 16.0.0,
current version 16.0.0)
/opt/local/lib/libz.1.dylib (compatibility version 1.0.0, current
version 1.2.7)
/opt/local/lib/libbz2.1.0.dylib (compatibility version 1.0.0, current
version 1.0.6)
/opt/local/lib/libexpat.1.dylib (compatibility version 8.0.0, current
version 8.0.0)
/System/Library/Frameworks/ApplicationServices.framework/Versions/A/ApplicationServices
(compatibility version 1.0.0, current version 38.0.0)
> We just had a release of MacPorts so it might be awhile before we have
> another one, and any such global post-destroot to remove .la files would have
> to be coded first, and its consequences understood.
Well, it's consequences are that glibtool will no longer propagate dependencies
like a virus.
> Meanwhile, what do we do today? Not update icu?
No, icu is actually kind of important … and unfortunately, it's kind of a root
project. I'm not sure the best answer here.
> And what will we do once the .la removal code you talk about is added? Won't
> we have to revbump almost every port?
At minimum, we should poke the buildbots to do a rebuild. I don't think a
revbump would be warranted for every port. The situation would clear itself up
as ports bumped themselves. The risk in not bumping is that someone might
still have a viral link which we didn't account for when we update something
again in the future, but rev-upgrade should catch those cases.
--Jeremy
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