Let travis build a clang version

.travis.yml

@@ -1,6 +1,7 @@
 language: cpp
 compiler:
  - gcc
+ - clang
 cache: apt
 before_install:
  - sudo apt-add-repository -y ppa:beineri/opt-qt521
@@ -9,7 +10,7 @@ before_install:
  - sudo apt-get update -qq
 install:
  - sudo apt-get install -y -qq cmake qt52base qt52svg qt52tools qt52x11extras
- - if [ "$CXX" = "g++" ]; then sudo apt-get install -y -qq g++-4.8; fi
+ - sudo apt-get install -y -qq g++-4.8
  - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8" CC="gcc-4.8"; fi
 before_script:
  - mkdir build

cmake/UseCXX11.cmake

@@ -4,7 +4,7 @@ endif()
 set(__USECXX11_CMAKE__ TRUE)
 
 if(APPLE)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++ -std=c++11")
 elseif(UNIX)
     # assume GCC, add C++0x/C++11 stuff
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")