[cfe-dev] [RFC][libcxx] Fixing "-stdlib=libc++ -lc++abi" on Linux -- Exporting libc++abi through libc++.so.

[Renato Golin via cfe-dev]

On 12 October 2015 at 12:19, David Chisnall via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
> If you can not modify the linkage of libstdc++ on your target platform, then the best solution is to use libstdc++ itself as the ABI library.

Do you mean only libsupc++ or the whole libstdc++?

Back to Erik's proposal, the clang driver had some similar logic to
Compiler-RT that was added and removed by me given the solutions and
complications I found.

>From compiler-rt, on GNU systems, I added libgcc_s or libgcc_eh
automatically, so one could use "--rtlib=compiler-rt" and get
everything working out of the box. But that breaks out when you want
to use libunwind, in the exact same way Erik's proposal will break if
it includes either libsupc++ or libc++abi.

Not controlling the base architecture is a problem, given that all
your dynamic objects already link and use whatever the platform gives
you. This takes us back to the drawing board.

What do we want from our high level libraries?

* Independent, good quality libraries? In which case testing
compatibility with other base libraries is unnecessary and all we test
are statically linked (or controlled dynamically linked) environments.

* Inter-operational, sometimes redundant libraries? In which case we
assume the target always has libgcc / libsupc++ and only ever replace
compiler-rt and libc++, not the other two.

I believe both solutions have huge problems, but I can't see the few
of us actually supporting *well* both use cases at the same time.

Ideas?

cheers,
--renato