[llvm-dev] How to build LLVM linked to libc++abi?

[Petr Hosek via llvm-dev]

See https://reviews.llvm.org/D8017 for reason why this is not supported. I
have a change https://reviews.llvm.org/D44671 that removes this
restriction, but I haven't yet convinced libc++ maintainers to get an
approval to merge this change.

On Sun, Sep 30, 2018 at 10:24 PM ardi <ardillasdelmonte at gmail.com> wrote:

> Thanks a lot, but tried it and I get this:
>
> CMake Error at projects/libcxx/CMakeLists.txt:361 (message):
>
>   LIBCXX_ENABLE_STATIC_ABI_LIBRARY is not supported on OS X
>
> Why is it not supported? If I manually embed libc++abi.a inside
> libc++.a it seems to work.
>
> Thanks!
>
> ardi
>
> On Mon, Oct 1, 2018 at 4:20 AM Petr Hosek <phosek at chromium.org> wrote:
> >
> > You can use LIBCXX_ENABLE_STATIC_ABI_LIBRARY=ON CMake option to
> statically link libc++abi into libc++.a. You can also use
> LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY=OFF to disable statically
> linking libc++abi into libc++.so (i.e. libc++abi will only be merged into
> libc++.a, not libc++.so).
> >
> > Similarly, you can also use LIBCXXABI_ENABLE_STATIC_UNWINDER=ON and
> LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY=OFF to the same for
> libunwind.
> >
> > Alternatively, you could rename libc++.a to libc++_internal.a and then
> create a linker script named libc++.a with the following content:
> >
> > INPUT(libc++_internal.a libc++abi.a)
> >
> > There's no support to do so in CMake at the moment, but it's something
> we've already discussed within Fuchsia as it'd be also useful for sanitizer
> runtimes so I might start a (separate) discussion about adding such support.
> >
> > On Sun, Sep 30, 2018 at 2:40 PM ardi via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >>
> >> Hi!
> >>
> >> I sometimes build LLVM with a static libc++.a in MacOS, so that I use
> >> the LLVM libc++ instead of the system-wide one. However, when doing
> >> so, I always get link errors when building LLVM, because the build
> >> system links with libc++.a, but not with libc++abi.a and so there are
> >> quite a few missing symbols that the linker cannot find.
> >>
> >> My workaround (which always seems to work) is to embed libc++abi
> >> inside of libc++ (with libtool, for example), but that's a hack for
> >> being in a hurry. BTW, note that I'm talking about building LLVM
> >> itself, not my programs (when you build your programs it doesn't hurt
> >> to add  -lc++abi to your link line, but when building LLVM, how are
> >> you supposed to do it? I've searched for a cleaner solution to this,
> >> but couldn't find any.
> >>
> >> Isn't there any LLVM build option for simply telling "hey! don't
> >> forget to add -lc++abi whenever you link to libc++" ?
> >>
> >> Thanks!
> >>
> >> ardi
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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