Perform clang-tidy on both cpp and cuda source.

.clang-tidy

@@ -1,4 +1,4 @@
-Checks: 'modernize-*,-modernize-make-*,-modernize-raw-string-literal,google-*,-google-default-arguments,-clang-diagnostic-#pragma-messages,readability-identifier-naming'
+Checks: 'modernize-*,-modernize-make-*,-modernize-use-auto,-modernize-raw-string-literal,google-*,-google-default-arguments,-clang-diagnostic-#pragma-messages,readability-identifier-naming'
 CheckOptions:
   - { key: readability-identifier-naming.ClassCase,           value: CamelCase  }
   - { key: readability-identifier-naming.StructCase,          value: CamelCase  }

CMakeLists.txt

@@ -123,8 +123,6 @@ file(GLOB_RECURSE SOURCES
 # Only add main function for executable target
 list(REMOVE_ITEM SOURCES ${PROJECT_SOURCE_DIR}/src/cli_main.cc)
 
-file(GLOB_RECURSE TEST_SOURCES "tests/cpp/*.cc")
-
 file(GLOB_RECURSE CUDA_SOURCES
     src/*.cu
     src/*.cuh
@@ -140,7 +138,7 @@ if(PLUGIN_DENSE_PARSER)
 endif()
 
 # rabit
-# TODO: Create rabit cmakelists.txt
+# TODO: Use CMakeLists.txt from rabit.
 set(RABIT_SOURCES
     rabit/src/allreduce_base.cc
     rabit/src/allreduce_robust.cc
@@ -151,14 +149,19 @@ set(RABIT_EMPTY_SOURCES
     rabit/src/engine_empty.cc
     rabit/src/c_api.cc
 )
+
 if(MINGW OR R_LIB)
   # build a dummy rabit library
   add_library(rabit STATIC ${RABIT_EMPTY_SOURCES})
 else()
   add_library(rabit STATIC ${RABIT_SOURCES})
 endif()
 
-if(USE_CUDA)
+if (GENERATE_COMPILATION_DATABASE)
+  set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+endif (GENERATE_COMPILATION_DATABASE)
+
+if(USE_CUDA AND (NOT GENERATE_COMPILATION_DATABASE))
   find_package(CUDA 8.0 REQUIRED)
   cmake_minimum_required(VERSION 3.5)
 
@@ -168,7 +171,7 @@ if(USE_CUDA)
 
   if(USE_NCCL)
     find_package(Nccl REQUIRED)
-    include_directories(${NCCL_INCLUDE_DIR})
+    cuda_include_directories(${NCCL_INCLUDE_DIR})
     add_definitions(-DXGBOOST_USE_NCCL)
   endif()
 
@@ -188,6 +191,39 @@ if(USE_CUDA)
     target_link_libraries(gpuxgboost ${NCCL_LIB_NAME})
   endif()
   list(APPEND LINK_LIBRARIES gpuxgboost)
+
+elseif (USE_CUDA AND GENERATE_COMPILATION_DATABASE)
+  # Enable CUDA language to generate a compilation database.
+  cmake_minimum_required(VERSION 3.8)
+
+  find_package(CUDA 8.0 REQUIRED)
+  enable_language(CUDA)
+  set(CMAKE_CUDA_COMPILER clang++)
+  set(CUDA_SEPARABLE_COMPILATION ON)
+  if (NOT CLANG_CUDA_GENCODE)
+    set(CLANG_CUDA_GENCODE "--cuda-gpu-arch=sm_35")
+  endif (NOT CLANG_CUDA_GENCODE)
+  set(CMAKE_CUDA_FLAGS " -Wno-deprecated  ${CLANG_CUDA_GENCODE} -fPIC ${GENCODE} -std=c++11 -x cuda")
+  message(STATUS "CMAKE_CUDA_FLAGS: ${CMAKE_CUDA_FLAGS}")
+
+  add_library(gpuxgboost STATIC ${CUDA_SOURCES})
+
+  if(USE_NCCL)
+    find_package(Nccl REQUIRED)
+    target_include_directories(gpuxgboost PUBLIC ${NCCL_INCLUDE_DIR})
+    target_compile_definitions(gpuxgboost PUBLIC -DXGBOOST_USE_NCCL)
+    target_link_libraries(gpuxgboost PUBLIC ${NCCL_LIB_NAME})
+  endif()
+
+  target_compile_definitions(gpuxgboost PUBLIC -DXGBOOST_USE_CUDA)
+  # A hack for CMake to make arguments valid for clang++
+  string(REPLACE "-x cu" "-x cuda" CMAKE_CUDA_COMPILE_PTX_COMPILATION
+    ${CMAKE_CUDA_COMPILE_PTX_COMPILATION})
+  string(REPLACE "-x cu" "-x cuda" CMAKE_CUDA_COMPILE_WHOLE_COMPILATION
+    ${CMAKE_CUDA_COMPILE_WHOLE_COMPILATION})
+  string(REPLACE "-x cu" "-x cuda" CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION
+    ${CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION})
+  target_include_directories(gpuxgboost PUBLIC cub)
 endif()
 
 
@@ -203,21 +239,20 @@ endif()
 
 add_library(objxgboost OBJECT ${SOURCES})
 
-
 # building shared library for R package
 if(R_LIB)
   find_package(LibR REQUIRED)
 
   list(APPEND LINK_LIBRARIES "${LIBR_CORE_LIBRARY}")
   MESSAGE(STATUS "LIBR_CORE_LIBRARY " ${LIBR_CORE_LIBRARY})
 
-  include_directories(
+  # Shared library target for the R package
+  add_library(xgboost SHARED $<TARGET_OBJECTS:objxgboost>)
+  include_directories(xgboost
     "${LIBR_INCLUDE_DIRS}"
     "${PROJECT_SOURCE_DIR}"
   )
 
-  # Shared library target for the R package
-  add_library(xgboost SHARED $<TARGET_OBJECTS:objxgboost>)
   target_link_libraries(xgboost ${LINK_LIBRARIES})
   # R uses no lib prefix in shared library names of its packages
   set_target_properties(xgboost PROPERTIES PREFIX "")
@@ -229,7 +264,7 @@ if(R_LIB)
   # use a dummy location for any other remaining installs
   set(CMAKE_INSTALL_PREFIX "${CMAKE_CURRENT_BINARY_DIR}/dummy_inst")
 
-# main targets: shared library & exe
+  # main targets: shared library & exe
 else()
   # Executable
   add_executable(runxgboost $<TARGET_OBJECTS:objxgboost> src/cli_main.cc)
@@ -252,20 +287,20 @@ else()
   add_dependencies(xgboost runxgboost)
 endif()
 
-
 # JVM
 if(JVM_BINDINGS)
     find_package(JNI QUIET REQUIRED)
 
-    include_directories(${JNI_INCLUDE_DIRS} jvm-packages/xgboost4j/src/native)
-
     add_library(xgboost4j SHARED
-        $<TARGET_OBJECTS:objxgboost>
-        jvm-packages/xgboost4j/src/native/xgboost4j.cpp)
-    set_output_directory(xgboost4j ${PROJECT_SOURCE_DIR}/lib)
+      $<TARGET_OBJECTS:objxgboost>
+      jvm-packages/xgboost4j/src/native/xgboost4j.cpp)
+    target_include_directories(xgboost4j
+      PRIVATE ${JNI_INCLUDE_DIRS}
+      PRIVATE jvm-packages/xgboost4j/src/native)
     target_link_libraries(xgboost4j
-        ${LINK_LIBRARIES}
-        ${JAVA_JVM_LIBRARY})
+      ${LINK_LIBRARIES}
+      ${JAVA_JVM_LIBRARY})
+    set_output_directory(xgboost4j ${PROJECT_SOURCE_DIR}/lib)
 endif()
 
 
@@ -274,18 +309,31 @@ if(GOOGLE_TEST)
   enable_testing()
   find_package(GTest REQUIRED)
 
+  file(GLOB_RECURSE TEST_SOURCES "tests/cpp/*.cc")
   auto_source_group("${TEST_SOURCES}")
-  include_directories(${GTEST_INCLUDE_DIRS})
 
-  if(USE_CUDA)
+  if(USE_CUDA AND (NOT GENERATE_COMPILATION_DATABASE))
     file(GLOB_RECURSE CUDA_TEST_SOURCES "tests/cpp/*.cu")
+    cuda_include_directories(${GTEST_INCLUDE_DIRS})
     cuda_compile(CUDA_TEST_OBJS ${CUDA_TEST_SOURCES})
+  elseif (USE_CUDA AND GENERATE_COMPILATION_DATABASE)
+    file(GLOB_RECURSE CUDA_TEST_SOURCES "tests/cpp/*.cu")
   else()
     set(CUDA_TEST_OBJS "")
   endif()
 
-  add_executable(testxgboost ${TEST_SOURCES} ${CUDA_TEST_OBJS} $<TARGET_OBJECTS:objxgboost>)
+  if (USE_CUDA AND GENERATE_COMPILATION_DATABASE)
+    add_executable(testxgboost ${TEST_SOURCES} ${CUDA_TEST_SOURCES}
+      $<TARGET_OBJECTS:objxgboost>)
+    target_include_directories(testxgboost PRIVATE cub)
+  else ()
+    add_executable(testxgboost ${TEST_SOURCES} ${CUDA_TEST_OBJS}
+      $<TARGET_OBJECTS:objxgboost>)
+  endif ()
+
   set_output_directory(testxgboost ${PROJECT_SOURCE_DIR})
+  target_include_directories(testxgboost
+    PRIVATE ${GTEST_INCLUDE_DIRS})
   target_link_libraries(testxgboost ${GTEST_LIBRARIES} ${LINK_LIBRARIES})
 
   add_test(TestXGBoost testxgboost)

Jenkinsfile

@@ -53,7 +53,7 @@ pipeline {
                     parallel (buildMatrix.findAll{it['enabled']}.collectEntries{ c ->
                         def buildName = utils.getBuildName(c)
                         utils.buildFactory(buildName, c, false, this.&buildPlatformCmake)
-                    })
+                    } + [ "clang-tidy" : { buildClangTidyJob() } ])
                 }
             }
         }
@@ -106,3 +106,22 @@ def buildPlatformCmake(buildName, conf, nodeReq, dockerTarget) {
         }
     }
 }
+
+/**
+ * Run a clang-tidy job on a GPU machine
+ */
+def buildClangTidyJob() {
+    def nodeReq = "linux && gpu && unrestricted"
+    node(nodeReq) {
+        unstash name: 'srcs'
+        echo "Running clang-tidy job..."
+        // Invoke command inside docker
+        // Install Google Test and Python yaml
+        dockerTarget = "clang_tidy"
+        dockerArgs = "--build-arg CUDA_VERSION=9.2"
+        sh """
+        ${dockerRun} ${dockerTarget} ${dockerArgs} tests/ci_build/clang_tidy.sh
+        """
+      }
+  }
+

doc/contribute.rst

@@ -19,6 +19,7 @@ Everyone is more than welcome to contribute. It is a way to make the project bet
 * `Documents`_
 * `Testcases`_
 * `Sanitizers`_
+* `clang-tidy`_
 * `Examples`_
 * `Core Library`_
 * `Python Package`_
@@ -169,6 +170,31 @@ environment variable:
 
 For details, please consult `official documentation <https://github.com/google/sanitizers/wiki>`_ for sanitizers.
 
+**********
+clang-tidy
+**********
+To run clang-tidy on both C++ and CUDA source code,  run the following command
+from the top level source tree:
+
+  .. code-black:: bash
+    cd /path/to/xgboost/
+    python3 tests/ci_build/tidy.py --gtest-path=/path/to/google-test
+
+The script requires the full path of Google Test library via the ``--gtest-path`` argument.
+
+Also, the script accepts two optional integer arguments, namely ``--cpp`` and ``--cuda``.
+By default they are both set to 1.  If you want to exclude CUDA source from
+linting, use:
+
+  .. code-black:: bash
+    cd /path/to/xgboost/
+    python3 tests/ci_build/tidy.py --cuda=0
+
+Similarly, if you want to exclude C++ source from linting:
+
+  .. code-black:: bash
+    cd /path/to/xgboost/
+    python3 tests/ci_build/tidy.py --cpp=0
 
 ********
 Examples

tests/ci_build/Dockerfile.clang_tidy

@@ -0,0 +1,45 @@
+ARG CUDA_VERSION
+FROM nvidia/cuda:$CUDA_VERSION-devel-ubuntu18.04
+
+# Environment
+ENV DEBIAN_FRONTEND noninteractive
+
+# Install all basic requirements
+RUN \
+    apt-get update && \
+    apt-get install -y tar unzip wget git build-essential cmake python3 python3-pip llvm-7 clang-tidy-7 clang-7
+
+# Set default clang-tidy version
+RUN \
+    update-alternatives --install /usr/bin/clang-tidy clang-tidy /usr/bin/clang-tidy-7 100 && \
+    update-alternatives --install /usr/bin/clang clang /usr/bin/clang-7 100
+
+# NCCL2 (License: https://docs.nvidia.com/deeplearning/sdk/nccl-sla/index.html)
+RUN \
+    export CUDA_SHORT=`echo $CUDA_VERSION | egrep -o '[0-9]+\.[0-9]'` && \
+    if [ "${CUDA_SHORT}" != "10.0" ]; then \
+    wget https://developer.download.nvidia.com/compute/redist/nccl/v2.2/nccl_2.2.13-1%2Bcuda${CUDA_SHORT}_x86_64.txz && \
+    tar xf "nccl_2.2.13-1+cuda${CUDA_SHORT}_x86_64.txz" && \
+    cp nccl_2.2.13-1+cuda${CUDA_SHORT}_x86_64/include/nccl.h /usr/include && \
+    cp nccl_2.2.13-1+cuda${CUDA_SHORT}_x86_64/lib/* /usr/lib && \
+    rm -f nccl_2.2.13-1+cuda${CUDA_SHORT}_x86_64.txz && \
+    rm -r nccl_2.2.13-1+cuda${CUDA_SHORT}_x86_64; fi
+
+# Install Python packages
+RUN \
+    pip3 install pyyaml
+
+ENV GOSU_VERSION 1.10
+
+# Install lightweight sudo (not bound to TTY)
+RUN set -ex; \
+    wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-amd64" && \
+    chmod +x /usr/local/bin/gosu && \
+    gosu nobody true
+
+# Default entry-point to use if running locally
+# It will preserve attributes of created files
+COPY entrypoint.sh /scripts/
+
+WORKDIR /workspace
+ENTRYPOINT ["/scripts/entrypoint.sh"]

tests/ci_build/clang_tidy.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+rm -rf gtest googletest-release-1.7.0
+wget -nc https://github.com/google/googletest/archive/release-1.7.0.zip
+unzip -n release-1.7.0.zip
+mv googletest-release-1.7.0 gtest && cd gtest
+cmake . && make
+mkdir lib && mv libgtest.a lib
+cd ..
+rm -rf release-1.7.0.zip*
+
+python3 tests/ci_build/tidy.py --gtest-path=${PWD}/gtest