Upgrade clang

.travis.yml

@@ -6,11 +6,13 @@ sudo: false
 addons:
   apt:
     sources:
+      - sourceline: "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.9 main"
+        key_url: "http://apt.llvm.org/llvm-snapshot.gpg.key"
       - ubuntu-toolchain-r-test
     packages:
       - cmake-data
       - cmake
-      - clang-3.8
+      - clang-3.9
       - libc++-dev
       - gcc-5
       - g++-5
@@ -20,7 +22,7 @@ compiler:
   - gcc
 
 install:
-    - if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.8 -stdlib=libc++" CC="clang-3.8"; fi
+    - if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.9 -stdlib=libc++" CC="clang-3.9"; fi
     - if [ "$CXX" = "g++" ]; then export CXX="g++-5" CC="gcc-5"; fi
 
 script: mkdir build && cd build && cmake .. && make && ./tests