[R] Remove dependency on gendef for Visual Studio builds (fixes #5608)

CMakeLists.txt

@@ -226,11 +226,12 @@ add_dependencies(xgboost runxgboost)
 
 #-- Installing XGBoost
 if (R_LIB)
+  include(cmake/RPackageInstallTargetSetup.cmake)
   set_target_properties(xgboost PROPERTIES PREFIX "")
   if (APPLE)
     set_target_properties(xgboost PROPERTIES SUFFIX ".so")
   endif (APPLE)
-  setup_rpackage_install_target(xgboost ${CMAKE_CURRENT_BINARY_DIR})
+  setup_rpackage_install_target(xgboost "${CMAKE_CURRENT_BINARY_DIR}/R-package-install")
   set(CMAKE_INSTALL_PREFIX "${CMAKE_CURRENT_BINARY_DIR}/dummy_inst")
 endif (R_LIB)
 if (MINGW)

R-package/CMakeLists.txt

@@ -36,3 +36,6 @@ set(LINKED_LIBRARIES_PRIVATE ${LINKED_LIBRARIES_PRIVATE} ${LIBR_CORE_LIBRARY} PA
 if (USE_OPENMP)
   target_link_libraries(xgboost-r PRIVATE OpenMP::OpenMP_CXX)
 endif ()
+
+set(LIBR_HOME "${LIBR_HOME}" PARENT_SCOPE)
+set(LIBR_EXECUTABLE "${LIBR_EXECUTABLE}" PARENT_SCOPE)

cmake/RPackageInstall.cmake.in

@@ -0,0 +1,34 @@
+# Commands to install the R package as a CMake install target
+
+function(check_call)
+  set(cmd COMMAND)
+  cmake_parse_arguments(
+    PARSE_ARGV 0
+    CALL_ARG "" "" "${cmd}"
+  )
+  string(REPLACE ";" " " commands "${CALL_ARG_COMMAND}")
+  message("Command: ${commands}")
+  execute_process(COMMAND ${CALL_ARG_COMMAND}
+                  OUTPUT_VARIABLE _out
+				  ERROR_VARIABLE _err
+				  RESULT_VARIABLE _res)
+  if(NOT "${_res}" EQUAL "0")
+    message(FATAL_ERROR "out: ${_out}, err: ${_err}, res: ${_res}")
+  endif()
+endfunction()
+
+# Important paths
+set(build_dir "@build_dir@")
+set(LIBR_EXECUTABLE "@LIBR_EXECUTABLE@")
+
+# Back up cmake_install.cmake
+file(WRITE "${build_dir}/R-package/src/Makevars" "all:")
+file(WRITE "${build_dir}/R-package/src/Makevars.win" "all:")
+
+# Install dependencies
+set(XGB_DEPS_SCRIPT
+    "deps = setdiff(c('data.table', 'magrittr', 'stringi'), rownames(installed.packages())); if(length(deps)>0) install.packages(deps, repo = 'https://cloud.r-project.org/')")
+check_call(COMMAND "${LIBR_EXECUTABLE}" -q -e "${XGB_DEPS_SCRIPT}")
+
+# Install the XGBoost R package
+check_call(COMMAND "${LIBR_EXECUTABLE}" CMD INSTALL --no-multiarch --build "${build_dir}/R-package")

cmake/RPackageInstallTargetSetup.cmake

@@ -0,0 +1,16 @@
+# Assembles the R-package files in build_dir;
+# if necessary, installs the main R package dependencies;
+# runs R CMD INSTALL.
+function(setup_rpackage_install_target rlib_target build_dir)
+  configure_file(${PROJECT_SOURCE_DIR}/cmake/RPackageInstall.cmake.in ${PROJECT_BINARY_DIR}/RPackageInstall.cmake @ONLY)
+  install(
+    DIRECTORY "${xgboost_SOURCE_DIR}/R-package"
+    DESTINATION "${build_dir}"
+    REGEX "src/*" EXCLUDE
+    REGEX "R-package/configure" EXCLUDE
+  )
+  install(TARGETS ${rlib_target}
+    LIBRARY DESTINATION "${build_dir}/R-package/src/"
+    RUNTIME DESTINATION "${build_dir}/R-package/src/")
+  install(SCRIPT ${PROJECT_BINARY_DIR}/RPackageInstall.cmake)
+endfunction()

cmake/Utils.cmake

@@ -110,38 +110,6 @@ function(format_gencode_flags flags out)
   set(${out} "${${out}}" PARENT_SCOPE)
 endfunction(format_gencode_flags flags)
 
-# Assembles the R-package files in build_dir;
-# if necessary, installs the main R package dependencies;
-# runs R CMD INSTALL.
-function(setup_rpackage_install_target rlib_target build_dir)
-  # backup cmake_install.cmake
-  install(CODE "file(COPY \"${build_dir}/R-package/cmake_install.cmake\"
-DESTINATION \"${build_dir}/bak\")")
-
-  install(CODE "file(REMOVE_RECURSE \"${build_dir}/R-package\")")
-  install(
-    DIRECTORY "${xgboost_SOURCE_DIR}/R-package"
-    DESTINATION "${build_dir}"
-    REGEX "src/*" EXCLUDE
-    REGEX "R-package/configure" EXCLUDE
-  )
-  install(TARGETS ${rlib_target}
-    LIBRARY DESTINATION "${build_dir}/R-package/src/"
-    RUNTIME DESTINATION "${build_dir}/R-package/src/")
-  install(CODE "file(WRITE \"${build_dir}/R-package/src/Makevars\" \"all:\")")
-  install(CODE "file(WRITE \"${build_dir}/R-package/src/Makevars.win\" \"all:\")")
-  set(XGB_DEPS_SCRIPT
-    "deps = setdiff(c('data.table', 'magrittr', 'stringi'), rownames(installed.packages()));\
-    if(length(deps)>0) install.packages(deps, repo = 'https://cloud.r-project.org/')")
-  install(CODE "execute_process(COMMAND \"${LIBR_EXECUTABLE}\" \"-q\" \"-e\" \"${XGB_DEPS_SCRIPT}\")")
-  install(CODE "execute_process(COMMAND \"${LIBR_EXECUTABLE}\" CMD INSTALL\
-    \"--no-multiarch\" \"--build\" \"${build_dir}/R-package\")")
-
-  # restore cmake_install.cmake
-  install(CODE "file(RENAME \"${build_dir}/bak/cmake_install.cmake\"
- \"${build_dir}/R-package/cmake_install.cmake\")")
-endfunction(setup_rpackage_install_target)
-
 macro(enable_nvtx target)
   find_package(NVTX REQUIRED)
   target_include_directories(${target} PRIVATE "${NVTX_INCLUDE_DIR}")

cmake/modules/FindLibR.cmake

@@ -23,7 +23,7 @@
 
 # Windows users might want to change this to their R version:
 if(NOT R_VERSION)
-  set(R_VERSION "3.4.1")
+  set(R_VERSION "4.0.0")
 endif()
 if(NOT R_ARCH)
   if("${CMAKE_SIZEOF_VOID_P}" STREQUAL "4")

doc/build.rst

@@ -369,8 +369,7 @@ Installing the development version
 ----------------------------------
 
 Make sure you have installed git and a recent C++ compiler supporting C++11 (See above
-sections for requirements of building C++ core).  On Windows, Rtools must be installed,
-and its bin directory has to be added to ``PATH`` during the installation.
+sections for requirements of building C++ core).
 
 Due to the use of git-submodules, ``devtools::install_github`` can no longer be used to install the latest version of R package.
 Thus, one has to run git to check out the code first:
@@ -397,18 +396,28 @@ On Windows, CMake with Visual C++ Build Tools (or Visual Studio) can be used to
 
 While not required, this build can be faster if you install the R package ``processx`` with ``install.packages("processx")``.
 
-.. note::
-  If you are using ``Rtools`` 4.0 or later, you need to also add the ``/usr/bin/`` directory from ``Rtools`` to the ``PATH`` environment variable.
+.. note:: Setting correct PATH environment variable on Windows
 
-Starting from the XGBoost directory, type:
+  If you are using Windows, make sure to include the right directories in the PATH environment variable.
+
+  * If you are using R 4.x with RTools 4.0:
+    - ``C:\rtools40\usr\bin``
+    - ``C:\rtools40\mingw64\bin``
+  * If you are using R 3.x with RTools 3.x:
+    - ``C:\Rtools\bin``
+    - ``C:\Rtools\mingw_64\bin``
+
+Open the Command Prompt and navigate to the XGBoost directory, and then run the following commands. Make sure to specify the correct R version.
 
 .. code-block:: bash
 
+  cd C:\path\to\xgboost
   mkdir build
   cd build
-  cmake .. -G"Visual Studio 16 2019" -A x64 -DR_LIB=ON
+  cmake .. -G"Visual Studio 16 2019" -A x64 -DR_LIB=ON -DR_VERSION=4.0.0
   cmake --build . --target install --config Release
 
+
 .. _r_gpu_support:
 
 Installing R package with GPU support
@@ -428,19 +437,30 @@ On Linux, starting from the XGBoost directory type:
 When default target is used, an R package shared library would be built in the ``build`` area.
 The ``install`` target, in addition, assembles the package files with this shared library under ``build/R-package`` and runs ``R CMD INSTALL``.
 
-On Windows, CMake with Visual C++ Build Tools (or Visual Studio) has to be used to build an R package with GPU support. Rtools must also be installed (perhaps, some other MinGW distributions with ``dlltool.exe`` would work, but that is not tested).
+On Windows, CMake with Visual Studio has to be used to build an R package with GPU support. Rtools must also be installed.
+
+.. note:: Setting correct PATH environment variable on Windows
+
+  If you are using Windows, make sure to include the right directories in the PATH environment variable.
+
+  * If you are using R 4.x with RTools 4.0:
+    - ``C:\rtools40\usr\bin``
+    - ``C:\rtools40\mingw64\bin``
+  * If you are using R 3.x with RTools 3.x:
+    - ``C:\Rtools\bin``
+    - ``C:\Rtools\mingw_64\bin``
+
+Open the Command Prompt and navigate to the XGBoost directory, and then run the following commands. Make sure to specify the correct R version.
 
 .. code-block:: bash
 
+  cd C:\path\to\xgboost
   mkdir build
   cd build
-  cmake .. -G"Visual Studio 14 2015 Win64" -DUSE_CUDA=ON -DR_LIB=ON
+  cmake .. -G"Visual Studio 16 2019" -A x64 -DR_LIB=ON -DR_VERSION=4.0.0
   cmake --build . --target install --config Release
 
-When ``--target xgboost`` is used, an R package DLL would be built under ``build/Release``.
-The ``--target install``, in addition, assembles the package files with this dll under ``build/R-package`` and runs ``R CMD INSTALL``.
-
-If cmake can't find your R during the configuration step, you might provide the location of its executable to cmake like this: ``-DLIBR_EXECUTABLE="C:/Program Files/R/R-3.4.1/bin/x64/R.exe"``.
+If CMake can't find your R during the configuration step, you might provide the location of R to CMake like this: ``-DLIBR_HOME="C:\Program Files\R\R-4.0.0"``.
 
 If on Windows you get a "permission denied" error when trying to write to ...Program Files/R/... during the package installation, create a ``.Rprofile`` file in your personal home directory (if you don't already have one in there), and add a line to it which specifies the location of your R packages user library, like the following: