[llvm-dev] Bootstrapping with in-tree libcxx

[Asiri Rathnayake via llvm-dev]

On Tue, Dec 27, 2016 at 2:45 PM, Carsten Mattner <carstenmattner at gmail.com>
wrote:

> On Tue, Dec 27, 2016 at 3:38 PM, Asiri Rathnayake
> <asiri.rathnayake at gmail.com> wrote:
> >
> >
> > On Tue, Dec 27, 2016 at 1:29 PM, Carsten Mattner via llvm-dev
> > <llvm-dev at lists.llvm.org> wrote:
> >>
> >> When I tried to build with -DLLVM_ENABLE_LIBCXX, I found out that
> >> it doesn't try to use the in-tree libcxx but looks for one built
> >> and installed in the system.
> >
> >
> > IIRC, -DLLVM_ENABLE_LIBCXX reduces to passing --stdlib=libc++ (see
> > [1]) to the compiler.
> >
> > What you can do is a two-stage build. On the first stage, build just
> > libc++ (ninja cxx cxxabi). On the second stage, re-configure with
> > -DLLVM_ENABLE_LIBCXX and build the rest of the tools. We have a
> > downstream builder that works this way to avoid a libstdc++ defect
> > on the host platform. I can't remember the exact details, can dig
> > them up if it helps.
>
> Yes please, that would be helpful as an interim workaround.
>

Hmm, I have mis-remembered. We do have a two-stage build, but probably not
what you want; stage-1 builds clang + libcxx using the host compiler (no
-DLLVM_USE_LIBCXX is passed). Then the stage-2 build uses the compiler
built on stage-1, along with the extra -DLLVM_USE_LIBCXX option.

I'll dig around a bit further, I thought this worked out of the box tbh.

/ Asiri
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