trying to install clang

.travis.yml

@@ -45,6 +45,18 @@ matrix:
       env: COMPILER=g++-5
 
     # from https://github.com/travis-ci/travis-ci/issues/6120
+    - os: linux
+      env:
+        - LLVM_VERSION=3.8.0
+        - LLVM_ARCHIVE_PATH=$HOME/clang+llvm.tar.xz
+        - COMPILER=clang++
+        - CXXFLAGS=-lc++
+      before_install:
+       - wget http://llvm.org/releases/$LLVM_VERSION/clang+llvm-$LLVM_VERSION-x86_64-linux-gnu-ubuntu-14.04.tar.xz -O $LLVM_ARCHIVE_PATH
+       - mkdir $HOME/clang-$LLVM_VERSION
+       - tar xf $LLVM_ARCHIVE_PATH -C $HOME/clang-$LLVM_VERSION --strip-components 1
+       - cd $HOME/clang-$LLVM_VERSION ; sudo cp -R * /usr/local/
+
     - os: linux
       env:
         - LLVM_VERSION=3.8.0