Re: [gentoo-dev] RFC: --as-needed to default LDFLAGS (Was: RFC: Should preserve-libs be enabled by default?)

[Ciaran McCreesh <ciaran.mccreesh@googlemail.com>]

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On Fri, 30 May 2008 21:50:49 -0500
Ravi Pinjala <ravi@p-static.net> wrote:
> Could you explain, for the benefit of us spectators, what these
> libtool problems are, and what cleaner solution you have in mind?
> It'd make this whole discussion a lot more comprehensible.

libtool links against dependencies-of-dependencies, rather than just
direct dependencies. This is correct behaviour on some platforms under
some situations (one example is static linking). But when linking
shared objects on modern Unixy platforms it's a pain in the ass since
you end up with a load of bogus shared object dependencies that break
things unnecessarily upon upgrades.

as-needed works around this by making the linker only link things from
the command line that resolve a name dependency (but name dependencies
aren't the only dependency type). This means that most of the extras
libtool adds in end up getting ignored, but it also means that things
the programmer has explicitly said to link in get ignored too.

The correct fix is to make libtool only link to dependencies of
dependencies when doing, for example, static linking. Debian has a
half-working patch for this that I posted earlier in the thread.

-- 
Ciaran McCreesh

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