-Wl,--as-needed

[Thiago Macieira]

George Staikos wrote:
>   This linker flag, -Wl,--as-needed, is causing some rather major
> problems for Kst build.

It's a flag turned on only if you give configure the option 
--enable-new-ldtags. It's like --enable-final, and we all know there are 
programs that don't work with --enable-final.

> If it's included, at least with my SuSE 9.2 
> install, it completely botches the GSL link and causes our plugins to
> crash when running. The only way to remove the flag (which makes it
> link properly), is to remove $(all_libraries), but that breaks compile
> on other platforms.  Does anyone know if there's a problem with SuSE
> 9.2's ld or gsl packages?  Or can we come up with a solution to
> optionally remove that flag?

See above.

But the problem you're reporting doesn't make sense. The only effect 
--as-needed has is remove unnecessary libraries from the ELF binaries. 
Whatever is needed will be pulled in normally. This indicates the problem 
is something else.

>   The details of the problem are that with the flag, when I link
> gslcblas and gsl into a plugin, it seems to drop gslcblas for no
> apparent reason.

Either it's an ld bug, or gslcblas isn't needed.

> It's definitely needed though.  The plugin crashes 
> due to missing symbol when running it without gslcblas linked in.

The linker adds the NEEDED symbol only for what the resulting binary 
requires *directly*. If your plugin doesn't need anything from gslcblas, 
it won't be listed in the NEEDED section. It doesn't matter if a library 
you use needs stuff from it --- the dependency isn't direct.

What probably is wrong is gsl and gslcblas themselves. I have seen many 
libraries that fail to link to their required dependencies, and in turn 
expect the final program to do that.

-- 
  Thiago Macieira  -  thiago (AT) macieira (DOT) info
    PGP/GPG: 0x6EF45358; fingerprint:
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3. Ac seo woruld wearð geborod, swá se Scieppend cweað "Gewurde Unix" and 
wundor fremede and him "Unix" genemned, þæt is se rihtendgesamnung.
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