[cfe-dev] Building clang 5 (for coroutines)

[Tim Northover via cfe-dev]

> This one fails, so the problem is in building the library. The errors look
> to me like things that are in the library itself are missing. I've included
> the full list below this time, and you can see, way down at the bottom, the
> errors are in linking libc++.so.1.0

The actual errors are pretty uninspiring (same as before: libstdc++
not being used). The compile command that's actually failing would be
useful. You can get that by running "make VERBOSE=1".

My best suspicion at the moment is that whatever docker is, it's
providing a weird toolchain that only links statically, which means
that the order of libraries matters more during the link phase and
libstdc++ might be too early. But we need to know exactly what's being
compiled to work out where to change the CMake scripts so it works.

I saw a similar case the other week from someone with a strange Red
Hat toolchain.

Cheers.

Tim.