[ci] fix R-package CI jobs and compatibility with OpenMP 15+ (fixes #5549, #5562) (#5563)

.ci/test_r_package_windows.ps1

@@ -132,13 +132,13 @@ Run-R-Code-Redirect-Stderr "options(install.packages.check.source = 'no'); insta
 #
 # MiKTeX always needs to be built to test a CRAN package.
 if (($env:COMPILER -eq "MINGW") -or ($env:R_BUILD_TYPE -eq "cran")) {
-    Download-File-With-Retries "https://github.com/microsoft/LightGBM/releases/download/v2.0.12/miktexsetup-4.0-x64.zip" -destfile "miktexsetup-x64.zip"
+    Download-File-With-Retries "https://github.com/microsoft/LightGBM/releases/download/v2.0.12/miktexsetup-5.2.0-x64.zip" -destfile "miktexsetup-x64.zip"
     Add-Type -AssemblyName System.IO.Compression.FileSystem
     [System.IO.Compression.ZipFile]::ExtractToDirectory("miktexsetup-x64.zip", "miktex")
     Write-Output "Setting up MiKTeX"
-    .\miktex\miktexsetup.exe --remote-package-repository="$env:CTAN_PACKAGE_ARCHIVE" --local-package-repository=./miktex/download --package-set=essential --quiet download ; Check-Output $?
+    .\miktex\miktexsetup_standalone.exe --remote-package-repository="$env:CTAN_PACKAGE_ARCHIVE" --local-package-repository=./miktex/download --package-set=essential --quiet download ; Check-Output $?
     Write-Output "Installing MiKTeX"
-    .\miktex\download\miktexsetup.exe --remote-package-repository="$env:CTAN_PACKAGE_ARCHIVE" --portable="$env:R_LIB_PATH/miktex" --quiet install ; Check-Output $?
+    .\miktex\download\miktexsetup_standalone.exe --remote-package-repository="$env:CTAN_PACKAGE_ARCHIVE" --portable="$env:R_LIB_PATH/miktex" --quiet install ; Check-Output $?
     Write-Output "Done installing MiKTeX"
 
     Run-R-Code-Redirect-Stderr "result <- processx::run(command = 'initexmf', args = c('--set-config-value', '[MPM]AutoInstall=1'), echo = TRUE, windows_verbatim_args = TRUE, error_on_status = TRUE)" ; Check-Output $?

CMakeLists.txt

@@ -142,7 +142,24 @@ if(USE_CUDA OR USE_CUDA_EXP)
 endif()
 
 if(USE_OPENMP)
-    find_package(OpenMP REQUIRED)
+    if(APPLE)
+        find_package(OpenMP)
+        if(NOT OpenMP_FOUND)
+            # libomp 15.0+ from brew is keg-only, so have to search in other locations.
+            # See https://github.com/Homebrew/homebrew-core/issues/112107#issuecomment-1278042927.
+            execute_process(COMMAND brew --prefix libomp
+                            OUTPUT_VARIABLE HOMEBREW_LIBOMP_PREFIX
+                            OUTPUT_STRIP_TRAILING_WHITESPACE)
+            set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp -I${HOMEBREW_LIBOMP_PREFIX}/include")
+            set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I${HOMEBREW_LIBOMP_PREFIX}/include")
+            set(OpenMP_C_LIB_NAMES omp)
+            set(OpenMP_CXX_LIB_NAMES omp)
+            set(OpenMP_omp_LIBRARY ${HOMEBREW_LIBOMP_PREFIX}/lib/libomp.dylib)
+            find_package(OpenMP REQUIRED)
+        endif()
+    else()
+        find_package(OpenMP REQUIRED)
+    endif()
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
 endif()
 

R-package/configure

@@ -1800,6 +1800,27 @@ if test `uname -s` = "Darwin"
 then
     OPENMP_CXXFLAGS='-Xclang -fopenmp'
     OPENMP_LIB='-lomp'
+
+    # libomp 15.0+ from brew is keg-only (i.e. not symlinked into the standard paths search by the linker),
+    # so need to search in other locations.
+    # See https://github.com/Homebrew/homebrew-core/issues/112107#issuecomment-1278042927.
+    #
+    # If Homebrew is found and libomp was installed with it, this code adds the necessary
+    # flags for the compiler to find libomp headers and for the linker to find libomp.dylib.
+    HOMEBREW_LIBOMP_PREFIX=""
+    if command -v brew &> /dev/null; then
+        ac_brew_openmp=no
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether OpenMP was installed via Homebrew" >&5
+$as_echo_n "checking whether OpenMP was installed via Homebrew... " >&6; }
+        brew --prefix libomp &>/dev/null && ac_brew_openmp=yes
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${ac_brew_openmp}" >&5
+$as_echo "${ac_brew_openmp}" >&6; }
+        if test "${ac_brew_openmp}" = yes; then
+            HOMEBREW_LIBOMP_PREFIX=`brew --prefix libomp`
+            OPENMP_CXXFLAGS="${OPENMP_CXXFLAGS} -I${HOMEBREW_LIBOMP_PREFIX}/include"
+            OPENMP_LIB="${OPENMP_LIB} -L${HOMEBREW_LIBOMP_PREFIX}/lib"
+        fi
+    fi
     ac_pkg_openmp=no
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether OpenMP will work in a package" >&5
 $as_echo_n "checking whether OpenMP will work in a package... " >&6; }

R-package/configure.ac

@@ -104,6 +104,25 @@ if test `uname -s` = "Darwin"
 then
     OPENMP_CXXFLAGS='-Xclang -fopenmp'
     OPENMP_LIB='-lomp'
+
+    # libomp 15.0+ from brew is keg-only (i.e. not symlinked into the standard paths search by the linker),
+    # so need to search in other locations.
+    # See https://github.com/Homebrew/homebrew-core/issues/112107#issuecomment-1278042927.
+    #
+    # If Homebrew is found and libomp was installed with it, this code adds the necessary
+    # flags for the compiler to find libomp headers and for the linker to find libomp.dylib.
+    HOMEBREW_LIBOMP_PREFIX=""
+    if command -v brew &> /dev/null; then
+        ac_brew_openmp=no
+        AC_MSG_CHECKING([whether OpenMP was installed via Homebrew])
+        brew --prefix libomp &>/dev/null && ac_brew_openmp=yes
+        AC_MSG_RESULT([${ac_brew_openmp}])
+        if test "${ac_brew_openmp}" = yes; then
+            HOMEBREW_LIBOMP_PREFIX=`brew --prefix libomp`
+            OPENMP_CXXFLAGS="${OPENMP_CXXFLAGS} -I${HOMEBREW_LIBOMP_PREFIX}/include"
+            OPENMP_LIB="${OPENMP_LIB} -L${HOMEBREW_LIBOMP_PREFIX}/lib"
+        fi
+    fi
     ac_pkg_openmp=no
     AC_MSG_CHECKING([whether OpenMP will work in a package])
     AC_LANG_CONFTEST(