From 2b64ccd5e36b0aea971d496096325a4cae78f607 Mon Sep 17 00:00:00 2001
From: vjymisal0 <vijay.looprai@gmail.com>
Date: Tue, 18 Aug 2026 19:02:59 +0530
Subject: [PATCH] fix(setup-r): export correct RTOOLS HOME env vars on Windows
 ARM64 and x64

On windows-11-arm runners, RTOOLS45_AARCH64_HOME (or RTOOLS44_AARCH64_HOME)
should be exported to point to the ARM64 toolchain directory rather than
leaving the ARM64 variable unset and defaulting to x86_64 paths.

Closes #1102

Signed-off-by: vjymisal0 <vijay.looprai@gmail.com>
---
 setup-r/src/installer.ts | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/setup-r/src/installer.ts b/setup-r/src/installer.ts
index a6a80faf..7e04bc31 100644
--- a/setup-r/src/installer.ts
+++ b/setup-r/src/installer.ts
@@ -557,40 +557,51 @@ async function acquireRtools(version: IRVersion) {
   let addpath = core.getInput("windows-path-include-rtools") === "true";
   core.exportVariable("_R_INSTALL_TIME_PATCHES_", "no");
   if (rtools45) {
-    if (addpath) {
-      if (ARCH == "arm64") {
+    if (ARCH == "arm64") {
+      core.exportVariable("RTOOLS45_AARCH64_HOME", "C:\\rtools45-aarch64");
+      if (addpath) {
         core.addPath(`C:\\rtools45-aarch64\\usr\\bin`);
         core.addPath(
           `C:\\rtools45-aarch64\\aarch64-w64-mingw32.static.posix\\bin`,
         );
-      } else {
+      }
+    } else {
+      core.exportVariable("RTOOLS45_HOME", "C:\\rtools45");
+      if (addpath) {
         core.addPath(`C:\\rtools45\\usr\\bin`);
         core.addPath(`C:\\rtools45\\x86_64-w64-mingw32.static.posix\\bin`);
       }
     }
   } else if (rtools44) {
-    if (addpath) {
-      if (ARCH == "arm64") {
+    if (ARCH == "arm64") {
+      core.exportVariable("RTOOLS44_AARCH64_HOME", "C:\\rtools44-aarch64");
+      if (addpath) {
         core.addPath(`C:\\rtools44-aarch64\\usr\\bin`);
         core.addPath(
           `C:\\rtools44-aarch64\\aarch64-w64-mingw32.static.posix\\bin`,
         );
-      } else {
+      }
+    } else {
+      core.exportVariable("RTOOLS44_HOME", "C:\\rtools44");
+      if (addpath) {
         core.addPath(`C:\\rtools44\\usr\\bin`);
         core.addPath(`C:\\rtools44\\x86_64-w64-mingw32.static.posix\\bin`);
       }
     }
   } else if (rtools43) {
+    core.exportVariable("RTOOLS43_HOME", "C:\\rtools43");
     if (addpath) {
       core.addPath(`C:\\rtools43\\usr\\bin`);
       core.addPath(`C:\\rtools43\\x86_64-w64-mingw32.static.posix\\bin`);
     }
   } else if (rtools42) {
+    core.exportVariable("RTOOLS42_HOME", "C:\\rtools42");
     if (addpath) {
       core.addPath(`C:\\rtools42\\usr\\bin`);
       core.addPath(`C:\\rtools42\\x86_64-w64-mingw32.static.posix\\bin`);
     }
   } else if (rtools40) {
+    core.exportVariable("RTOOLS40_HOME", "C:\\rtools40");
     if (addpath) {
       core.addPath(`C:\\rtools40\\usr\\bin`);
       // If we use Rtools40 and R 4.2.0 or later, then we need to add this