Allow using msys2 instead of cygwin

Author: tobil4sk

action.yml

@@ -37,6 +37,9 @@ inputs:
     description: The prefix of the cache keys.
     required: false
     default: v1
+  windows-environment:
+    description: Whether to use `cygwin` (default) or `msys2` for windows installs.
+    required: false
   github-token:
     description: DO NOT SET THIS.
     required: false

dist/index.js

@@ -86,6 +86,23 @@ export const ALLOW_PRERELEASE_OPAM = core.getBooleanInput(
   },
 );
 
+export const WINDOWS_ENVIRONMENT: "cygwin" | "msys2" = (() => {
+  const input = core.getInput("windows-environment");
+
+  if (!(PLATFORM === "windows" || input === "")) {
+    core.error("windows-environment is only supported on windows");
+  }
+
+  if (input === "msys2" || input === "cygwin") {
+    return input;
+  }
+
+  if (input !== "") {
+    core.error("unrecognized value for windows-environment");
+  }
+  return "cygwin";
+})();
+
 export const CACHE_PREFIX = core.getInput("cache-prefix", {
   required: false,
   trimWhitespace: true,

dist/post/index.js

@@ -10,6 +10,7 @@ import {
   saveOpamCache,
 } from "./cache.js";
 import {
+  CYGWIN_ROOT,
   CYGWIN_ROOT_BIN,
   DUNE_CACHE,
   DUNE_CACHE_ROOT,
@@ -18,6 +19,7 @@ import {
   OPAM_ROOT,
   PLATFORM,
   RESOLVED_COMPILER,
+  WINDOWS_ENVIRONMENT,
 } from "./constants.js";
 import { installDune } from "./dune.js";
 import {
@@ -29,7 +31,7 @@ import {
   update,
 } from "./opam.js";
 import { retrieveOpamLocalPackages } from "./packages.js";
-import { setupCygwin } from "./windows.js";
+import { prepareMsys2, setupCygwin } from "./windows.js";
 
 export async function installer() {
   if (core.isDebug()) {
@@ -64,13 +66,24 @@ export async function installer() {
   }
   const { opamCacheHit, cygwinCacheHit } = await restoreOpamCaches();
   if (PLATFORM === "windows") {
-    await setupCygwin();
-    if (!cygwinCacheHit) {
-      await saveCygwinCache();
+    switch (WINDOWS_ENVIRONMENT) {
+      case "msys2": {
+        const msys2Root = await prepareMsys2();
+        await setupOpam(msys2Root);
+        break;
+      }
+      case "cygwin":
+        await setupCygwin();
+        if (!cygwinCacheHit) {
+          await saveCygwinCache();
+        }
+        core.addPath(CYGWIN_ROOT_BIN);
+        await setupOpam(CYGWIN_ROOT);
+        break;
     }
-    core.addPath(CYGWIN_ROOT_BIN);
+  } else {
+    await setupOpam();
   }
-  await setupOpam();
   if (!opamCacheHit) {
     await repositoryRemoveAll();
     await repositoryAddAll(OPAM_REPOSITORIES);

packages/setup-ocaml/src/constants.ts

@@ -8,7 +8,6 @@ import * as semver from "semver";
 import {
   ALLOW_PRERELEASE_OPAM,
   ARCHITECTURE,
-  CYGWIN_ROOT,
   GITHUB_TOKEN,
   OPAM_DISABLE_SANDBOXING,
   PLATFORM,
@@ -86,7 +85,7 @@ async function acquireOpam() {
   });
 }
 
-async function initializeOpam() {
+async function initializeOpam(prefix?: string) {
   await core.group("Initialise opam state", async () => {
     if (PLATFORM !== "windows") {
       try {
@@ -104,7 +103,7 @@ async function initializeOpam() {
     const extraOptions = [];
     if (PLATFORM === "windows") {
       extraOptions.push("--cygwin-local-install");
-      extraOptions.push(`--cygwin-location=${CYGWIN_ROOT}`);
+      extraOptions.push(`--cygwin-location=${prefix}`);
     }
     if (OPAM_DISABLE_SANDBOXING) {
       extraOptions.push("--disable-sandboxing");
@@ -119,9 +118,9 @@ async function initializeOpam() {
   });
 }
 
-export async function setupOpam() {
+export async function setupOpam(prefix?: string) {
   await acquireOpam();
-  await initializeOpam();
+  await initializeOpam(prefix);
 }
 
 export async function installOcaml(ocamlCompiler: string) {

packages/setup-ocaml/src/installer.ts

@@ -115,3 +115,58 @@ export async function setupCygwin() {
     await io.cp(setup, CYGWIN_ROOT);
   });
 }
+
+function getPacmanPath(msys2Root: string): string {
+  return path.join(msys2Root, "usr", "bin", "pacman");
+}
+
+async function testMsys2Installation(path: string): Promise<void> {
+  try {
+    await fs.access(path);
+  } catch {
+    throw new Error(`No msys2 installation found at: ${path}.`);
+  }
+}
+
+async function getMsys2Install(): Promise<[root: string, pacmanPath: string]> {
+  const msys2Root = process.env.MSYS2_ROOT;
+
+  // MSYS2_ROOT takes priority
+  if (msys2Root) {
+    await testMsys2Installation(msys2Root);
+    return [msys2Root, getPacmanPath(msys2Root)];
+  }
+  try {
+    // check for pacman from PATH
+    const pacmanPath = await io.which("pacman", true);
+    return [path.dirname(path.dirname(path.dirname(pacmanPath))), pacmanPath];
+  } catch {
+    // finally check the default msys directory
+    const defaultRoot = "C:\\msys64";
+    testMsys2Installation(defaultRoot);
+    return [defaultRoot, getPacmanPath(defaultRoot)];
+  }
+}
+
+export async function prepareMsys2(): Promise<string> {
+  return await core.group("Install needed Msys2 packages", async () => {
+    const [root, pacmanPath] = await getMsys2Install();
+    // core update
+    await exec(pacmanPath, ["-Syu", "--noconfirm"]);
+    // packages needed for opam
+    const packages = [
+      "curl",
+      "diffutils",
+      "m4",
+      "make",
+      "mingw-w64-i686-gcc",
+      "mingw-w64-x86_64-gcc",
+      "patch",
+      "perl",
+      "rsync",
+      "unzip",
+    ];
+    await exec(pacmanPath, ["-Syu", "--noconfirm", ...packages]);
+    return root;
+  });
+}