Re: [gentoo-dev] Packaging changes in LLVM 10

[Michał Górny]

On Mon, 2020-03-16 at 13:37 +0100, Gerion Entrup wrote:
> Am Montag, 16. März 2020, 09:23:49 CET schrieb Michał Górny:
> > Hi,
> >
> > Since 10.0.0 final is around the corner, I'd like to take a minute to
> > inform developers of packaging changes in Gentoo that affect its
> > revdeps.  Following frequently repeated requests from Gentoo developers
> > and users, LLVM 10 is stopping to use BUILD_SHARED_LIBS=ON, i.e. split
> > shared libraries.  Instead, we'll be using the 'dylib' model recommended
> > upstream.
> >
> > This means that sys-devel/{llvm,clang} no longer install those small
> > libLLVM*.so and libclang*.so files.  Instead, one big libLLVM-${ver}.so
> > and libclang-cpp.so.${sover} are installed (yes, I know this historical
> > inconsistency sucks).  Also note that Clang continues installing
> > libclang.so which is a *C* (not C++) library.
> >
> > Most of LLVM revdeps should not have problem with LLVM dylib, as it was
> > the de-facto standard on other distros.  llvm-config handles it
> > transparently.  If you're dealing with a custom build system that
> > doesn't handle it, it's as simple as trying '-lLLVM' first (note that
> > you will '-L' due to slotting).
> >
> > Clang revdeps may have trouble with clang-cpp library since it's
> > a fairly recent addition.  Again, the solution is simple: '-lclang-cpp'
> > (repeating: do not confuse it with -lclang which is a different library
> > for historical reasons).
> >
> > sys-devel/lld does not install any libraries anymore.  If you ever need
> > them, please ping me and we'll try to come up with something upstream.
> >
> > dev-util/lldb installs liblldb.so.  However, I'm not familiar with that
> > library and I don't know if it has any consumers.
> >
> > If you need any help, please don't hesitate to ping me.
>
> Hi,
>
> when I compile LLVM for myself, I also always choose SHARED_LIBS simply
> because of RAM usage when linking the libraries. In the past, I was not
> able to link the single library on my 16 GB machine (I have not tested
> it now and this could be dependent on other circumstances). What is the
> current expected RAM usage for LLVM 10?
>

To be honest, I don't know.  I have 8G here, and it's entirely
sufficient for -j3 build.  I don't experience major linking problems
as I used to, so things might have improved on binutils end.

-- 
Best regards,
Michał Górny