[llvm-dev] libcxx build error.

[Tim Northover via llvm-dev]

On 26 September 2015 at 18:45, Srikanth Bemineni via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Is libcxx supported on gcc 4.4.7 which comes with CentOS 6.6. Are LLVM
> releases very much constrained to the gcc version specified in the software
> requirements ?

It's probably quite a stretch to say that LLVM 3.4 is still supported
in any sense. We're not going to release another point fix for it, so
you're going to be relying on anyone who happens to have a vague
memory from that era (I don't). As for whether it compiles on CentOS
6, apparently not.

Generally we write to the C++ standard, with hacks reluctantly added
for popular compilers at any given release's time. Releases of CentOS
and RHEL in long-term support are not usually viewed favourably (they
tend to be ridiculously ancient).

> I followed the patch mentioned in this link
> http://comments.gmane.org/gmane.comp.compilers.clang.scm/87139

Thanks for reporting that on the list (honestly), it could be useful
for others coming along after you at least.

> /home/bemineni/llvm/llvm-3.4.2/projects/libcxx/include/tuple:461: error:
> ‘std::__1::__tuple_impl<std::__1::__tuple_indices<_Indx ...>, _Tp
> ...>::__tuple_impl(std::__1::__tuple_impl<std::__1::__tuple_indices<_Indx
> ...>, _Tp ...>&&)’ cannot be defaulted

This looks like something that's not guarded by
_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS (after your patch) but should be.
This one seems fairly easy to fix, but judging by "grep '= default' |
wc" vs "grep LIBCPP_... | wc" you might be in for a tedious afternoon
if you want to fix all instances. If you're lucky, GCC 4.4 will
support *most* instances of "= default".

Cheers.

Tim.