Add clang-tidy support.

Currently, we run only a very small subset of checks (the static analysis checks).

For PRs clang-tidy reports only if the regression is triggered by one of the
modified lines.

There is a cron-job mode which is unused and it could be enabled (through travis)
in future. If enabled now, it reports multitude of issues (reports stop at 10K
lines of log due to travis limit).

.travis.yml

@@ -12,6 +12,9 @@ addons: &addons
 cache:
   apt: true
   ccache: true
+#  directories:
+#    - $BUILD_DEPS
+
 
 # Do not build our sync branch.
 branches:
@@ -22,38 +25,112 @@ matrix:
   # Abort all builds on a single failing matrix entry.
   fast_finish: true
 
+  exclude:
+    # Note: Workaround travis-ci/travis-ci#4681
+    # Exclude default job which lacks our included environment variables.
+    - os: linux
+
   include:
     # There seems to be a hard limit to how many machines a Travis build will
     # across all platforms. By interleaving OS X, the hope is to get in the
     # queue faster while not blocking Linux builds from occuring.
     - os: linux
+      env: TOOL=clang-format
       addons:
         apt:
           sources: *sources
           packages: ['clang-format-3.9']
       compiler: clang
 
+    - os: linux
+      env: TOOL=clang-tidy
+      addons:
+        apt:
+          sources: *sources
+          packages: ['clang-3.9', 'clang-tidy-3.9', 'libstdc++-6-dev']
+      compiler: clang
+
+install:
+  - export BUILD_DEPS="${TRAVIS_BUILD_DIR}/deps"
+  - mkdir ${BUILD_DEPS} && cd ${BUILD_DEPS}
+  - |
+    if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
+      CMAKE_URL="https://cmake.org/files/v3.6/cmake-3.6.0-Linux-x86_64.tar.gz"
+      mkdir cmake && travis_retry wget --no-check-certificate --quiet -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake
+      export PATH=${BUILD_DEPS}/cmake/bin:${PATH}
+    fi
+
+
+    # Go to the Root directory
+  - cd ..
+
 script:
+- echo "Copying and generating header files." && echo -en travis_fold:start:install.headers"
+- |
+  # We need to put in place all relevant headers before running clang-tidy.
+  if [[ $TOOL == 'clang-tidy' ]] && \
+       [[ "$TRAVIS_EVENT_TYPE" = "cron" ]] || [[ "$TRAVIS_PULL_REQUEST" != "false" ]] ; then
+
+    mkdir ../build
+    cd ../build
+    export CC=clang-3.9
+    export CXX=clang++-3.9
+    cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -Dall=On -Dx11=Off ../root
+    # We need to prebuild a minimal set of targets which are responsible for header copy
+    # or generation.
+    make -j4 move_headers intrinsics_gen ClangCommentCommandList ClangCommentCommandInfo \
+             ClangCommentHTMLNamedCharacterReferences ClangCommentHTMLTagsProperties     \
+             ClangCommentNodes ClangAttrImpl ClangStmtNodes ClangAttrClasses             \
+             ClangAttrDump ClangCommentHTMLTags ClangDeclNodes ClangAttrVisitor          \
+             ClangDiagnosticCommon ClangARMNeon ClangDiagnosticIndexName                 \
+             ClangDiagnosticParse ClangDiagnosticComment ClangDiagnosticFrontend         \
+             ClangDiagnosticGroups ClangDiagnosticSerialization ClangDiagnosticLex       \
+             ClangDiagnosticSema ClangAttrList ClangAttrHasAttributeImpl                 \
+             ClangDiagnosticAST ClangDiagnosticDriver ClangDiagnosticAnalysis            \
+             ClangDriverOptions ClangAttrParserStringSwitches ClangAttrParsedAttrList    \
+             ClangAttrTemplateInstantiate ClangAttrSpellingListIndex                     \
+             ClangAttrParsedAttrImpl ClangAttrParsedAttrKinds
+  fi
+- echo -en 'travis_fold:end:install.headers\\r'
+
 - |
   if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then
-    BASE_COMMIT=$(git rev-parse $TRAVIS_BRANCH)
-    echo "Running clang-format-3.9 against branch $TRAVIS_BRANCH, with hash $BASE_COMMIT"
-    COMMIT_FILES=$(git diff --name-only $BASE_COMMIT | grep -i -v LinkDef)
-    RESULT_OUTPUT="$(git-clang-format-3.9 --commit $BASE_COMMIT --diff --binary `which clang-format-3.9` $COMMIT_FILES)"
+    if [[ $TOOL == 'clang-format' ]]; then
+      BASE_COMMIT=$(git rev-parse $TRAVIS_BRANCH)
+      echo "Running clang-format-3.9 against branch $TRAVIS_BRANCH, with hash $BASE_COMMIT"
+      COMMIT_FILES=$(git diff --name-only $BASE_COMMIT | grep -i -v LinkDef)
+      RESULT_OUTPUT="$(git-clang-format-3.9 --commit $BASE_COMMIT --diff --binary `which clang-format-3.9` $COMMIT_FILES)"
 
-    if [ "$RESULT_OUTPUT" == "no modified files to format" ] \
-      || [ "$RESULT_OUTPUT" == "clang-format did not modify any files" ] ; then
-
-      echo "clang-format passed."
-      exit 0
-    else
-      echo "clang-format failed."
-      echo "To reproduce it locally please run"
-      echo -e "\tgit checkout $TRAVIS_BRANCH"
-      echo -e "\tgit-clang-format --commit $BASE_COMMIT --diff --binary $(which clang-format)"
-      echo "$RESULT_OUTPUT"
-      exit 1
+      if [ "$RESULT_OUTPUT" == "no modified files to format" ] \
+        || [ "$RESULT_OUTPUT" == "clang-format did not modify any files" ] ; then
+
+        echo "clang-format passed."
+        exit 0
+      else
+        echo "clang-format failed."
+        echo "To reproduce it locally please run"
+        echo -e "\tgit checkout $TRAVIS_BRANCH"
+        echo -e "\tgit-clang-format --commit $BASE_COMMIT --diff --binary $(which clang-format)"
+        echo "$RESULT_OUTPUT"
+        exit 1
+      fi
+    elif [[ $TOOL == 'clang-tidy' ]]; then
+      echo "Running clang-tidy-3.9 only against the changes in branch $TRAVIS_BRANCH."
+      echo "Command: git diff -U0 $TRAVIS_BRANCH..master | clang-tidy-diff-3.9.py -p1 -clang-tidy-binary \$(which clang-tidy-3.9) -checks=-*,clang-analyzer-*"
+
+      cd ../root/
+      # Workaround for travis issue: travis-ci/travis-ci#6069
+      git remote set-branches --add origin master
+      git fetch
+      git diff -U0 origin/master | clang-tidy-diff-3.9.py -p1 -clang-tidy-binary $(which clang-tidy-3.9) -checks=-*,clang-analyzer-*
     fi
+  elif [[ "$TRAVIS_EVENT_TYPE" = "cron" ]] && [[ $TOOL == 'clang-tidy' ]]; then
+    # We need to ignore our vendor drops.
+    FILES_REGEX='^.*root\/(?!interpreter\/|core\/clib)'
+
+    echo "Running clang-tidy-3.9 against branch $TRAVIS_BRANCH."
+    echo "run-clang-tidy-3.9.py -j4 -clang-tidy-binary $(which clang-tidy-3.9) -checks=-*,clang-analyzer-* $FILES_REGEX"
+    run-clang-tidy-3.9.py -j4 -clang-tidy-binary $(which clang-tidy-3.9) -checks=-*,clang-analyzer-* $FILES_REGEX
   fi
 
 on_failure: