test clang 4.0.1 on travis

.travis.yml

@@ -31,7 +31,7 @@ matrix:
     - os: linux
       sudo: false
       compiler: ": clang"
-      env: JOBS=8 CXX="ccache clang++-3.9 -Qunused-arguments" CC="clang-3.9" TRIGGER=true
+      env: JOBS=8 CXX="ccache clang++-4.0 -Qunused-arguments" CC="clang-4.0" TRIGGER=true
       addons:
         apt:
           sources: [ 'ubuntu-toolchain-r-test']
@@ -39,7 +39,7 @@ matrix:
     - os: linux
       sudo: false
       compiler: ": clang-coverage"
-      env: JOBS=8 COVERAGE=true CXX="ccache clang++-3.9 -Qunused-arguments" CC="clang-3.9"
+      env: JOBS=8 COVERAGE=true CXX="ccache clang++-4.0 -Qunused-arguments" CC="clang-4.0"
       addons:
         apt:
           sources: [ 'ubuntu-toolchain-r-test']
@@ -82,12 +82,12 @@ before_script:
  - source bootstrap.sh
  - |
    if [[ $(uname -s) == 'Linux' ]]; then
-     mason install clang++ 3.9.1
-     export PATH=$(mason prefix clang++ 3.9.1)/bin:${PATH}
-     mason install llvm-cov 3.9.1
-     export PATH=$(mason prefix llvm-cov 3.9.1)/bin:${PATH}
+     mason install clang++ 4.0.1
+     export PATH=$(mason prefix clang++ 4.0.1)/bin:${PATH}
+     mason install llvm-cov 4.0.1
+     export PATH=$(mason prefix llvm-cov 4.0.1)/bin:${PATH}
      which llvm-cov
-     export LLVM_COV="$(mason prefix llvm-cov 3.9.1)/bin/llvm-cov"
+     export LLVM_COV="$(mason prefix llvm-cov 4.0.1)/bin/llvm-cov"
    fi
  - ccache --version
  - ccache -p || true

bootstrap.sh

@@ -11,7 +11,7 @@ todo
 - shrink icu data
 '
 
-MASON_VERSION="v0.11.1"
+MASON_VERSION="v0.14.2"
 
 function setup_mason() {
     if [[ ! -d ./.mason ]]; then