Travis CI with Clang 3.4 and C++11 - c++

Question

Is it possible to get Travis CI working with Clang that is capable of C++11? (I want Clang, not GCC, I already have GCC 4.8 working in Travis CI.) It appears that the version that is there pre-installed is not C++11 capable. All my attempts at installing any newer version end up failing because of this:
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/bits/move.h:57:
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/type_traits:269:39: error:
use of undeclared identifier '__float128'
struct __is_floating_point_helper<__float128>
I have seen the -D__STRICT_ANSI__ trick but that clashes with other things for me.
Is it possible to get it working? See also my .travis.yml.

Answer 1

There is now a better way to do this.
sudo: false
dist: trusty
language: cpp
os:
- linux
compiler:
- gcc
- clang
install:
# /usr/bin/gcc is 4.6 always, but gcc-X.Y is available.
- if [[ $CXX = g++ ]]; then export CXX="g++-4.9" CC="gcc-4.9"; fi
# /usr/bin/clang has a conflict with gcc, so use clang-X.Y.
- if [[ $CXX = clang++ ]]; then export CXX="clang++-3.5" CC="clang-3.5"; fi
addons:
apt:
sources:
- ubuntu-toolchain-r-test
- llvm-toolchain-precise-3.5 # not sure why we needed this
packages:
- gcc-4.9
- g++-4.9
- clang-3.5
(The explicit sudo: false will let it build in Docker (for speed) even if you have a pre-docker repo, according to Travis support.)
Thanks to solarce at Travis support for noticing my error and fixing the docs.
http://docs.travis-ci.com/user/apt/
http://genbattle.bitbucket.org/blog/2016/01/17/c++-travis-ci/
https://github.com/open-source-parsers/jsoncpp/blob/master/.travis.yml (for up-to-date example)

Answer 2

Here is a part of my .travis.yml files (mostly taken from this file).
language: cpp
compiler:
- clang
- gcc
before_install:
# g++4.8.1
- if [ "$CXX" == "g++" ]; then sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test; fi
# clang 3.4
- if [ "$CXX" == "clang++" ]; then sudo add-apt-repository -y ppa:h-rayflood/llvm; fi
- sudo apt-get update -qq
install:
# g++4.8.1
- if [ "$CXX" = "g++" ]; then sudo apt-get install -qq g++-4.8; fi
- if [ "$CXX" = "g++" ]; then export CXX="g++-4.8"; fi
# clang 3.4
- if [ "$CXX" == "clang++" ]; then sudo apt-get install --allow-unauthenticated -qq clang-3.4; fi
- if [ "$CXX" == "clang++" ]; then export CXX="clang++-3.4"; fi
script:
- $CXX --version
EDIT because it can be very useful to add libc++ for travis. Up to my knowledge, there is no Linux package for libc++, so one has to compile it "by hand". Do not forget -stdlib=libc++ in CXXFLAGS while compiling with clang.
install:
# clang 3.4
- if [ "$CXX" == "clang++" ]; then sudo apt-get install --allow-unauthenticated -qq clang-3.4; fi
- if [ "$CXX" == "clang++" ]; then export CXXFLAGS="-std=c++0x -stdlib=libc++"; fi
- if [ "$CXX" == "clang++" ]; then svn co --quiet http://llvm.org/svn/llvm-project/libcxx/trunk libcxx; fi
- if [ "$CXX" == "clang++" ]; then cd libcxx/lib && bash buildit; fi
- if [ "$CXX" == "clang++" ]; then sudo cp ./libc++.so.1.0 /usr/lib/; fi
- if [ "$CXX" == "clang++" ]; then sudo mkdir /usr/include/c++/v1; fi
- if [ "$CXX" == "clang++" ]; then cd .. && sudo cp -r include/* /usr/include/c++/v1/; fi
- if [ "$CXX" == "clang++" ]; then cd /usr/lib && sudo ln -sf libc++.so.1.0 libc++.so; fi
- if [ "$CXX" == "clang++" ]; then sudo ln -sf libc++.so.1.0 libc++.so.1 && cd $cwd; fi
- if [ "$CXX" == "clang++" ]; then export CXX="clang++-3.4"; fi

Answer 3

It appears that the clang developers fixed this when you build in -std=gnu++11 mode.
Are you able to build with that flag instead of __STRICT_ANSI__?
http://llvm.org/bugs/show_bug.cgi?id=13530
http://llvm.org/viewvc/llvm-project?view=revision&revision=184476