Merge pull request #1066 from stan-dev/rtools45-compat

RTools45 compatibility

Author: andrjohns

.github/workflows/R-CMD-check.yaml

@@ -25,7 +25,7 @@ jobs:
         config:
           - {os: macOS-latest, r: 'devel', rtools: '', opencl: true}
           - {os: macOS-latest, r: 'release', rtools: '', opencl: true}
-          - {os: windows-latest, r: 'devel', rtools: '44'}
+          - {os: windows-latest, r: 'devel', rtools: '45'}
           - {os: windows-latest, r: 'release', rtools: '44'}
           - {os: windows-latest, r: 'oldrel', rtools: '43'}
           - {os: ubuntu-latest, r: 'devel', rtools: '', opencl: true}

R/install.R

@@ -895,8 +895,10 @@ rtools4x_version <- function() {
     rtools_ver <- "42"
   } else if (R.version$minor < "4.0") {
     rtools_ver <- "43"
-  } else {
+  } else if (R.version$minor < "5.0") {
     rtools_ver <- "44"
+  } else {
+    rtools_ver <- "45"
   }
   rtools_ver
 }