[PATCH] D125683: [runtimes] Replace LIBCXX_ENABLE_STATIC_ABI_LIBRARY & friends by a new LIBCXX_CXX_ABI choice

[Petr Hosek via Phabricator via cfe-commits]

phosek added inline comments.


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Comment at: clang/cmake/caches/Fuchsia-stage2.cmake:124
     set(RUNTIMES_${target}_LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
-    set(RUNTIMES_${target}_LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
     set(RUNTIMES_${target}_LIBCXX_ABI_VERSION 2 CACHE STRING "")
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ldionne wrote:
> phosek wrote:
> > ldionne wrote:
> > > Note that I am removing these options here because I don't think they are required -- since we specify `LIBCXXABI_ENABLE_SHARED=OFF`, there is no shared libc++abi to link against, so we should already be linking against `libc++abi.a` regardless of this change.
> > This option was set to merge `libc++abi.a` into `libc++.a` so to achieve the same effect, presumably we would need to set `-DLIBCXX_CXX_ABI=libcxxabi-objects`?
> I agree this is suspicious, but why is there no `LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY` specified here then? I can add `-DLIBCXX_CXX_ABI=libcxxabi-objects`, I just want to make sure we both understand what's going on.
This is intentional. We are merging `libc++abi.a` into `libc++.a` but we ship `libc++abi.so` and `libc++.so` as separate (and use the generated linker script to pull in `libc++abi.so` when you pass `-lc++` to linker). I'd be fine merging `libc++abi.so` into `libc++.so` as well, but we'll need to figure out a transition plan since there are several places in our build right now that expect `libc++abi.so` to exist. We cannot land this change as is because that would break the `-static-libstdc++` use case, since Clang driver only passes `-lc++` to the linker and not `-lc++abi` and there's nothing that would pull `libc++abi.a` in.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D125683/new/

https://reviews.llvm.org/D125683