theraven added inline comments.
================
Comment at: include/__mutex_base:246
@@ -266,3 +245,3 @@
-class _LIBCPP_TYPE_VIS condition_variable
+class _LIBCPP_TYPE_VIS condition_variable : private
__libcxx_support::condition_variable
{
----------------
espositofulvio wrote:
> theraven wrote:
> > espositofulvio wrote:
> > > theraven wrote:
> > > > Does this change the ABI for a mutex on *NIX platforms? We can't
> > > > change the class layout for existing platforms (though we can indirect
> > > > things via typedefs).
> > > My hunch is that it doesn't, std::condition_variable has no data member
> > > now and the first base class (__libcxx_support::condition_variable)
> > > contains only pthread_cond_t which will be effectively laid out at the
> > > starting address of the object, as it was previously for
> > > std::condition_variable,. I will check this out later in the evening
> > > though.
> > I *think* that it's correct, but it's worth compiling a program that has
> > one compilation unit using the old header and another using the new one and
> > check that it's able to interoperate correctly.
> >
> > Also check whether this depends on the implementation of the condition
> > variable. On FreeBSD, the pthread types are all pointers (currently -
> > we're going to have some painful ABI breakage at some point when we move
> > them to being something that can live in shared memory). In glibc, they're
> > structures. I don't think that you'll end up with different padding in the
> > ABI from wrapping them in a class, but it's worth checking.
> > it's worth compiling a program that has one compilation unit using the old
> > header and another using the new one and check that it's able to
> > interoperate correctly
>
> Unfortunately this isn't going to work, some simbols are now defined in
> __libcxx_support and not in std (they are just made available through using),
> so an object file that includes the old header won't link against the new
> library (unreferenced symbols). The alternative is to create inline
> forwarding methods.
>
>
>
That's going to need some more refactoring then. Breaking the public ABI of
libc++ would be a show-stopper.
Repository:
rL LLVM
http://reviews.llvm.org/D11781
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