feat: fallback arm64 to x64 architecture for win32 platform (#131)

* feat: fallback arm64 to x64 architecture for win32 platform

closes https://github.com/oven-sh/setup-bun/issues/130

* [autofix.ci] apply automated fixes

* ci: test on windows-11-arm runner

* refactor: move logic to getEffectiveArch func

* [autofix.ci] apply automated fixes

* feat: add warning message for windows arm64 fallback to x64

* [autofix.ci] apply automated fixes

* feat: don't mention arch in warning msg aboout fallback

* [autofix.ci] apply automated fixes

* debug time

* [autofix.ci] apply automated fixes

* feat: force baseline for win32 arm fallback to x64

* [autofix.ci] apply automated fixes

* ci: dont use windows-11-arm on setup bun from download url

* fix

* [autofix.ci] apply automated fixes

* fix

* [autofix.ci] apply automated fixes

* fix

* [autofix.ci] apply automated fixes

* fix

* [autofix.ci] apply automated fixes

* fix

* [autofix.ci] apply automated fixes

* apply changes

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* [autofix.ci] apply automated fixes

* docs: clarify

* [autofix.ci] apply automated fixes

* test: add unit tests for getAvx2 Windows ARM64 fallback logic (#154)

* Initial plan

* Add unit tests for getAvx2 function

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* Consolidate duplicate test assertions in getAvx2 tests

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* Fix whitespace formatting in test file

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* test: add unit tests for getArchitecture and getAvx2 Windows ARM64 fallback logic (#153)

* Initial plan

* Add unit tests for getArchitecture function

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* Remove unused import in utils.spec.ts

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Merge pr-131 and resolve test file conflicts

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>
Co-authored-by: Jozef Steinhübl <generalkubo@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>

.github/workflows/test.yml

@@ -50,6 +50,7 @@ jobs:
           - ubuntu-latest
           - macos-latest
           - windows-latest
+          - windows-11-arm
         bun-version:
           - latest
           - canary
@@ -98,6 +99,7 @@ jobs:
           - ubuntu-latest
           - macos-latest
           - windows-latest
+          - windows-11-arm
 
         file:
           - name: package.json (packageManager bun@1.1.0)

src/download-url.ts

@@ -1,6 +1,6 @@
 import { compareVersions, satisfies, validate } from "compare-versions";
 import { Input } from "./action";
-import { getArchitecture, getPlatform, request } from "./utils";
+import { getArchitecture, getAvx2, getPlatform, request } from "./utils";
 
 export async function getDownloadUrl(options: Input): Promise<string> {
   const { customUrl } = options;
@@ -50,8 +50,14 @@ async function getSemverDownloadUrl(options: Input): Promise<string> {
 
   const eversion = encodeURIComponent(tag ?? version);
   const eos = encodeURIComponent(os ?? getPlatform());
-  const earch = encodeURIComponent(arch ?? getArchitecture());
+  const earch = encodeURIComponent(
-  const eavx2 = encodeURIComponent(avx2 === false ? "-baseline" : "");
+    getArchitecture(os ?? getPlatform(), arch ?? process.arch),
+  );
+  const eavx2 = encodeURIComponent(
+    getAvx2(os ?? getPlatform(), arch ?? process.arch, avx2) === false
+      ? "-baseline"
+      : "",
+  );
   const eprofile = encodeURIComponent(profile === true ? "-profile" : "");
 
   const { href } = new URL(

src/utils.ts

@@ -42,13 +42,33 @@ export function getPlatform(): string {
   return platform;
 }
 
-export function getArchitecture(): string {
+export function getArchitecture(os: string, arch: string): string {
-  const arch = process.arch;
+  if (os === "windows" && (arch === "aarch64" || arch === "arm64")) {
-  if (arch === "arm64") return "aarch64";
+    warning(
+      [
+        "⚠️ Bun does not provide native arm64 builds for Windows.",
+        "Using x64 baseline build which will run through Microsoft's x64 emulation layer.",
+        "This may result in reduced performance and potential compatibility issues.",
+        "💡 For best performance, consider using x64 Windows runners or other platforms with native support.",
+      ].join("\n"),
+    );
 
+    return "x64";
+  }
+
+  if (arch === "arm64") return "aarch64";
   return arch;
 }
 
+export function getAvx2(os: string, arch: string, avx2?: boolean): boolean {
+  // Temporary workaround for absence of arm64 builds on Windows (#130)
+  if (os === "windows" && (arch === "aarch64" || arch === "arm64")) {
+    return false;
+  }
+
+  return avx2 ?? true;
+}
+
 const FILE_VERSION_READERS = {
   "package.json": (content: string) => {
     const pkg = JSON.parse(content);

tests/utils.spec.ts

@@ -0,0 +1,124 @@
+import { afterEach, describe, expect, it, spyOn } from "bun:test";
+import { getArchitecture, getAvx2 } from "../src/utils";
+import * as core from "@actions/core";
+
+describe("getArchitecture", () => {
+  let warningSpy: ReturnType<typeof spyOn>;
+
+  afterEach(() => {
+    warningSpy?.mockRestore();
+  });
+
+  it("should return x64 for Windows with arm64 architecture", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("windows", "arm64");
+
+    expect(result).toBe("x64");
+    expect(warningSpy).toHaveBeenCalledTimes(1);
+    expect(warningSpy).toHaveBeenCalledWith(
+      expect.stringContaining(
+        "⚠️ Bun does not provide native arm64 builds for Windows."
+      )
+    );
+  });
+
+  it("should return x64 for Windows with aarch64 architecture", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("windows", "aarch64");
+
+    expect(result).toBe("x64");
+    expect(warningSpy).toHaveBeenCalledTimes(1);
+    expect(warningSpy).toHaveBeenCalledWith(
+      expect.stringContaining(
+        "⚠️ Bun does not provide native arm64 builds for Windows."
+      )
+    );
+  });
+
+  it("should return aarch64 for non-Windows platforms with arm64", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("linux", "arm64");
+
+    expect(result).toBe("aarch64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return aarch64 for macOS with arm64", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("darwin", "arm64");
+
+    expect(result).toBe("aarch64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return original arch value for x64", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("windows", "x64");
+
+    expect(result).toBe("x64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return original arch value for x86", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("linux", "x86");
+
+    expect(result).toBe("x86");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+
+  it("should return original arch value for aarch64 on Linux", () => {
+    warningSpy = spyOn(core, "warning");
+    const result = getArchitecture("linux", "aarch64");
+
+    expect(result).toBe("aarch64");
+    expect(warningSpy).not.toHaveBeenCalled();
+  });
+});
+
+describe("getAvx2", () => {
+  it("should return false when called with os: 'windows' and arch: 'arm64'", () => {
+    const result = getAvx2("windows", "arm64");
+    expect(result).toBe(false);
+  });
+
+  it("should return false when called with os: 'windows' and arch: 'aarch64'", () => {
+    const result = getAvx2("windows", "aarch64");
+    expect(result).toBe(false);
+  });
+
+  it("should return false when called with os: 'windows', arch: 'arm64', and avx2: true", () => {
+    const result = getAvx2("windows", "arm64", true);
+    expect(result).toBe(false);
+  });
+
+  it("should return false when called with os: 'windows', arch: 'aarch64', and avx2: false", () => {
+    const result = getAvx2("windows", "aarch64", false);
+    expect(result).toBe(false);
+  });
+
+  it("should return the provided avx2 value (true) when specified and not on Windows ARM64", () => {
+    expect(getAvx2("linux", "x64", true)).toBe(true);
+    expect(getAvx2("darwin", "x64", true)).toBe(true);
+    expect(getAvx2("windows", "x64", true)).toBe(true);
+  });
+
+  it("should return the provided avx2 value (false) when specified and not on Windows ARM64", () => {
+    expect(getAvx2("linux", "x64", false)).toBe(false);
+    expect(getAvx2("darwin", "x64", false)).toBe(false);
+    expect(getAvx2("windows", "x64", false)).toBe(false);
+  });
+
+  it("should return true by default when avx2 is not specified and not on Windows ARM64", () => {
+    // x64 architecture on various platforms
+    expect(getAvx2("linux", "x64")).toBe(true);
+    expect(getAvx2("darwin", "x64")).toBe(true);
+    expect(getAvx2("windows", "x64")).toBe(true);
+
+    // ARM architecture on non-Windows platforms
+    expect(getAvx2("linux", "arm64")).toBe(true);
+    expect(getAvx2("linux", "aarch64")).toBe(true);
+    expect(getAvx2("darwin", "arm64")).toBe(true);
+    expect(getAvx2("darwin", "aarch64")).toBe(true);
+  });
+});