llvm dev - Nov 2019 - clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-14.04 links against libc++ instead of libstdc++

The Ubuntu 14.04 prebuilt binary on http://releases.llvm.org/download.html#9.0.0
seems to be built against libc++:

% nm -Cu libLLVMCore.a | sed -n '/ std::__1/{p;q}'
                 U std::__1::basic_string<char,
std::__1::char_traits<char>, std::__1::allocator<char>
>::find(char, unsigned long) const

Is this expected? With a brief reading of
https://llvm.org/docs/ReleaseProcess.html, I guess the prebuilt binaries were
likely built with llvm/utils/release/test-release.sh, but I cannot find any
LLVM_ENABLE_LIBCXX setting in the script.

> -----Original Message-----
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of
Fangrui Song
> via llvm-dev
...
> The Ubuntu 14.04 prebuilt binary on
> http://releases.llvm.org/download.html#9.0.0 seems to be built against
> libc++:
> 
> % nm -Cu libLLVMCore.a | sed -n '/ std::__1/{p;q}'
>                  U std::__1::basic_string<char,
std::__1::char_traits<char>,
> std::__1::allocator<char> >::find(char, unsigned long) const
> 
> Is this expected? With a brief reading of
> https://llvm.org/docs/ReleaseProcess.html, I guess the prebuilt binaries
> were likely built with llvm/utils/release/test-release.sh, but I cannot
find any
> LLVM_ENABLE_LIBCXX setting in the script.
Yes, I believe I added that to "-configure-flags" for Ubuntu 14.  I
don't specifically recall why I added it, but it's *possible* that I
would've done that if the libstdc++ and/or glibc were missing necessary
features for some of the llvm projects or test suite programs.

I can rebuild it without that extra configure flags and upload that in addition.
I guess I'd use the same triple for now and rename the tarball with some
kind of suffix to clarify.

-Brian