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

[Petr Hosek via llvm-dev]

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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180930/508877c0/attachment.html>