Building llvm 6 under Linux Alpine - build

Question

I am trying to build llvm 6 on a Linux Alpine Docker container.
Here is what I have done, following these instructions:
apk add build-base
apk add python
apk add zlib
svn co http://llvm.org/svn/llvm-project/llvm/tags/RELEASE_600/final/ llvm
svn co http://llvm.org/svn/llvm-project/cfe/tags/RELEASE_600/final/ clang
svn co http://llvm.org/svn/llvm-project/libcxx/tags/RELEASE_600/final/ libcxx
(all svn calls in the appropriate folders, obviously)
Then I make my build folder and do cmake -G "Unix Makefiles" ../llvm
However, when I get to make, after a bit it dies with the following:
[ 11%] Building CXX object projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/algorithm.cpp.o
In file included from /root/llvm/projects/libcxx/include/ostream:140:0,
from /root/llvm/projects/libcxx/include/istream:163,
from /root/llvm/projects/libcxx/include/random:1646,
from /root/llvm/projects/libcxx/src/algorithm.cpp:11:
/root/llvm/projects/libcxx/include/locale: In function '_Tp std::__1::__num_get_signed_integral(const char*, const char*, std::__1::ios_base::iostate&, int)':
/root/llvm/projects/libcxx/include/locale:739:76: error: there are no arguments to 'strtoll_l' that depend on a template parameter, so a declaration of 'strtoll_l' must be available [-fpermissive]
long long __ll = strtoll_l(__a, &__p2, __base, _LIBCPP_GET_C_LOCALE);
^
/root/llvm/projects/libcxx/include/locale:739:76: note: (if you use '-fpermissive', G++ will accept your code, but allowing the use of an undeclared name is deprecated)
/root/llvm/projects/libcxx/include/locale: In function '_Tp std::__1::__num_get_unsigned_integral(const char*, const char*, std::__1::ios_base::iostate&, int)':
/root/llvm/projects/libcxx/include/locale:779:86: error: there are no arguments to 'strtoull_l' that depend on a template parameter, so a declaration of 'strtoull_l' must be available [-fpermissive]
unsigned long long __ll = strtoull_l(__a, &__p2, __base, _LIBCPP_GET_C_LOCALE);
^
At global scope:
cc1plus: warning: unrecognized command line option '-Wno-noexcept-type'
make[2]: *** [projects/libcxx/lib/CMakeFiles/cxx_objects.dir/build.make:63: projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/algorithm.cpp.o] Error 1
Am I missing something, like a dependency? Or is this a known bug that needs fixing? What am I supposed to do to get a working, recent llvm + clang + libc++ on Linux Alpine?

Answer 1

At time of writing, there is an open pull request to add llvm6 to aports. Because it involves a lot of patches and tweaks, it seems building from source on alpine is not easy to figure out.
So, we have every reason to believe that there will soon be an official llvm6 package, but until one appears, you can use the APKBUILD from that PR to build llvm from source yourself.
Install Dependencies
abuild is the utility Alpine uses to compile its packages.
apk add alpine-sdk
abuild will install most of the dependencies you need automatically, but it diffutils is missing from the dependency list in the PR.
apk add diffutils
Stop being root
abuild refuses to run as root, so if you haven't already, create a user account. I'm using the username apk:
adduser apk
adduser apk abuild
su - apk
abuild-keygen -a
Clone the PR and compile
git clone --depth=1 -b pr-llvm-6 https://github.com/xentec/aports
cd aports/main/llvm6
abuild -r
The abuild -r will take a very long time indeed, so if you're following along, now might be a good time to take your lunch break.
Install the resulting package
If everything succeeded, abuild will have placed a bunch of .apk files in $HOME/packages/main. Assuming again that the user account is named apk and its home folder is /home/apk, then, as root
cp /home/apk/.abuild/*.rsa.pub /etc/apk/keys
apk add /home/apk/packages/main/$(uname -m)/*.apk
With thanks and credit to the author of the PR: https://github.com/xentec
EDIT: Dockerfile Snippet
Since your question mentions Docker, here's a RUN command you can insert:
# Temporary workaround for there not being an llvm6 apk yet
# Open PR for llvm6 package: https://github.com/alpinelinux/aports/pull/3583
# See https://stackoverflow.com/questions/50258121/building-llvm-6-under-linux-alpine
RUN export BUILD_DEPS='alpine-sdk git diffutils' \
&& apk update \
&& apk add $BUILD_DEPS \
&& adduser -D apk \
&& adduser apk abuild \
&& sudo -iu apk abuild-keygen -a \
&& sudo -iu apk git clone --depth=1 -b pr-llvm-6 https://github.com/xentec/aports \
&& sudo -iu apk sh -xec 'cd aports/main/llvm6; abuild -r' \
&& cp /home/apk/.abuild/*.rsa.pub /etc/apk/keys \
&& apk add /home/apk/packages/main/$(uname -m)/*.apk \
&& deluser --remove-home apk \
&& rm -rf /var/cache/apk/APKINDEX* \
&& apk del --no-cache $BUILD_DEPS

Answer 2

I used Dan's code and pushed it to DockerHub.
Since it takes a while to build locally, a pre-built image might be useful for some :)
py36-alpine-llvm6(DockerHub)