[ci] [R-package] use R 4.2.1 in Windows CI jobs (fixes #4881)

.ci/test_r_package_windows.ps1

@@ -54,11 +54,13 @@ Remove-From-Path ".*PostgreSQL.*"
 Remove-From-Path ".*\\R\\.*"
 Remove-From-Path ".*R Client.*"
 Remove-From-Path ".*rtools40.*"
+Remove-From-Path ".*rtools42.*"
 Remove-From-Path ".*shells.*"
 Remove-From-Path ".*Strawberry.*"
 Remove-From-Path ".*tools.*"
 
 Remove-Item C:\rtools40 -Force -Recurse -ErrorAction Ignore
+Remove-Item C:\rtools42 -Force -Recurse -ErrorAction Ignore
 
 # Get details needed for installing R components
 #
@@ -74,11 +76,11 @@ if ($env:R_MAJOR_VERSION -eq "3") {
   $env:RTOOLS_EXE_FILE = "rtools35-x86_64.exe"
   $env:R_WINDOWS_VERSION = "3.6.3"
 } elseif ($env:R_MAJOR_VERSION -eq "4") {
-  $RTOOLS_INSTALL_PATH = "C:\rtools40"
+  $RTOOLS_INSTALL_PATH = "C:\rtools42"
   $env:RTOOLS_BIN = "$RTOOLS_INSTALL_PATH\usr\bin"
-  $env:RTOOLS_MINGW_BIN = "$RTOOLS_INSTALL_PATH\mingw64\bin"
-  $env:RTOOLS_EXE_FILE = "rtools40v2-x86_64.exe"
-  $env:R_WINDOWS_VERSION = "4.1.3"
+  $env:RTOOLS_MINGW_BIN = "$RTOOLS_INSTALL_PATH\x86_64-w64-mingw32.static.posix\bin"
+  $env:RTOOLS_EXE_FILE = "rtools42-5253-5107.exe"
+  $env:R_WINDOWS_VERSION = "4.2.1"
 } else {
   Write-Output "[ERROR] Unrecognized R version: $env:R_VERSION"
   Check-Output $false
@@ -147,7 +149,7 @@ Write-Output "Building R package"
 # R CMD check is not used for MSVC builds
 if ($env:COMPILER -ne "MSVC") {
 
-  $PKG_FILE_NAME = "lightgbm_*.tar.gz"
+  $PKG_FILE_NAME = "lightgbm_$env:LGB_VER.tar.gz"
   $LOG_FILE_NAME = "lightgbm.Rcheck/00check.log"
 
   if ($env:R_BUILD_TYPE -eq "cmake") {

.github/workflows/r_package.yml

@@ -82,7 +82,7 @@ jobs:
             task: r-package
             compiler: MINGW
             toolchain: MSYS
-            r_version: 4.1
+            r_version: 4.2
             build_type: cmake
           # Visual Studio 2019
           - os: windows-2019
@@ -96,7 +96,7 @@ jobs:
             task: r-package
             compiler: MSVC
             toolchain: MSVC
-            r_version: 4.1
+            r_version: 4.2
             build_type: cmake
           ###############
           # CRAN builds #
@@ -111,7 +111,7 @@ jobs:
             task: r-package
             compiler: MINGW
             toolchain: MSYS
-            r_version: 4.1
+            r_version: 4.2
             build_type: cran
           - os: ubuntu-latest
             task: r-package
@@ -165,6 +165,7 @@ jobs:
         shell: pwsh -command ". {0}"
         run: |
           $env:BUILD_SOURCESDIRECTORY = $env:GITHUB_WORKSPACE
+          $env:LGB_VER = (Get-Content -TotalCount 1 $env:BUILD_SOURCESDIRECTORY\VERSION.txt).trim().replace('rc', '-')
           $env:TOOLCHAIN = "${{ matrix.toolchain }}"
           $env:R_VERSION = "${{ matrix.r_version }}"
           $env:R_BUILD_TYPE = "${{ matrix.build_type }}"

R-package/README.md

@@ -97,13 +97,18 @@ After installing `Rtools` and `CMake`, be sure the following paths are added to
     - If you have `Rtools` 4.0, example:
         - `C:\rtools40\mingw64\bin`
         - `C:\rtools40\usr\bin`
+    - If you have `Rtools` 4.2, example:
+        - `C:\rtools42\x86_64-w64-mingw32.static.posix\bin`
+        - `C:\rtools42\usr\bin`
 * `CMake`
     - example: `C:\Program Files\CMake\bin`
 * `R`
     - example: `C:\Program Files\R\R-3.6.1\bin`
 
 NOTE: Two `Rtools` paths are required from `Rtools` 4.0 onwards because paths and the list of included software was changed in `Rtools` 4.0.
 
+NOTE: `Rtools42` takes a very different approach to the compiler toolchain than previous releases, and how you install it changes what is required to build packages. See ["Howto: Building R 4.2 and packages on Windows"](https://cran.r-project.org/bin/windows/base/howto-R-4.2.html).
+
 #### Windows Toolchain Options
 
 A "toolchain" refers to the collection of software used to build the library. The R package can be built with three different toolchains.

R-package/configure.win

@@ -79,7 +79,8 @@ ac_inet_pton="no"
 cat > conftest.cpp <<EOL
 #include <ws2tcpip.h>
 int main() {
-  void* p = inet_pton;
+  int (*fptr)(int, const char*, void*);
+  fptr = &inet_pton;
   return 0;
 }
 EOL

R-package/tests/testthat/test_dataset.R

@@ -219,8 +219,8 @@ test_that("lgb.Dataset: Dataset should be able to construct from matrix and retu
 
 test_that("cpp errors should be raised as proper R errors", {
   testthat::skip_if(
-    Sys.getenv("COMPILER", "") == "MSVC" && as.integer(R.Version()[["major"]]) < 4L
-    , message = "Skipping on R 3.x and Visual Studio"
+    Sys.getenv("COMPILER", "") == "MSVC"
+    , message = "Skipping on Visual Studio"
   )
   data(agaricus.train, package = "lightgbm")
   train <- agaricus.train