Update pnpm version detection logic (#11445)

The code we use to detect the version of `pnpm` based on lockfiles is hard to follow. It doesn't pick and executable, it instead of *sometimes* overrides the `PATH` for these utilities with a prepended alternate path. 

This means that there is no one single place where we definitively specify which version of `pnpm` that is used, so much as *hope* that the `PATH` has the correct version on it. I don't know that we *can* specify an executable outside of the build container, and it's unclear, since this is a package, whether this utility is used outside of a build container setting.

In this pull request I cleaned up the code and updated the logic to include the `pnpm 7` and `pnpm 8` changes requested, with no changes yet to implement `pnpm 9`.

It's possible that we want to rewrite this detection logic from scratch to avoid this roundabout way of "finding" the executable, but I haven't done that here.

.changeset/cold-boxes-tan.md

@@ -0,0 +1,6 @@
+---
+'@vercel/build-utils': minor
+---
+
+Update pnpm version detection logic
+Add support for pnpm 9

packages/build-utils/src/fs/run-user-scripts.ts

@@ -546,8 +546,7 @@ export function getEnvForPackageManager({
     detectedLockfile,
     detectedPackageManager,
     path: newPath,
-    yarnNodeLinker,
-  } = getPathForPackageManager({
+  } = getPathOverrideForPackageManager({
     cliType,
     lockfileVersion,
     nodeVersion,
@@ -558,36 +557,172 @@ export function getEnvForPackageManager({
     ...env,
   };
 
-  if (newPath) {
+  const alreadyInPath = (newPath: string) => {
+    const oldPath = env.PATH ?? '';
+    return oldPath.split(path.delimiter).includes(newPath);
+  };
+
+  if (newPath && !alreadyInPath(newPath)) {
     // Ensure that the binaries of the detected package manager are at the
     // beginning of the `$PATH`.
     const oldPath = env.PATH + '';
     newEnv.PATH = `${newPath}${path.delimiter}${oldPath}`;
-  }
-
-  if (yarnNodeLinker) {
-    newEnv.YARN_NODE_LINKER = yarnNodeLinker;
-  }
 
-  if (detectedLockfile && detectedPackageManager) {
-    // For pnpm we also show the version of the lockfile we found
-    const versionString =
-      cliType === 'pnpm' ? `version ${lockfileVersion} ` : '';
+    if (detectedLockfile && detectedPackageManager) {
+      // For pnpm we also show the version of the lockfile we found
+      const versionString =
+        cliType === 'pnpm' ? `version ${lockfileVersion} ` : '';
 
-    console.log(
-      `Detected \`${detectedLockfile}\` ${versionString}generated by ${detectedPackageManager}`
-    );
-
-    if (cliType === 'bun') {
-      console.warn(
-        'Warning: Bun is used as a package manager at build time only, not at runtime with Functions'
+      console.log(
+        `Detected \`${detectedLockfile}\` ${versionString}generated by ${detectedPackageManager}`
       );
+
+      if (cliType === 'bun') {
+        console.warn(
+          'Warning: Bun is used as a package manager at build time only, not at runtime with Functions'
+        );
+      }
     }
   }
 
+  if (cliType === 'yarn' && !env.YARN_NODE_LINKER) {
+    newEnv.YARN_NODE_LINKER = 'node-modules';
+  }
+
   return newEnv;
 }
 
+type DetectedPnpmVersion =
+  | 'not found'
+  | 'pnpm 7'
+  | 'pnpm 8'
+  | 'pnpm 9'
+  | 'corepack_enabled';
+
+function detectPnpmVersion(
+  lockfileVersion: number | undefined,
+  corepackEnabled: boolean
+): DetectedPnpmVersion {
+  switch (true) {
+    case corepackEnabled:
+      return 'corepack_enabled';
+    case lockfileVersion === undefined:
+      return 'not found';
+    case lockfileVersion === 5.3 || lockfileVersion === 5.4:
+      return 'pnpm 7';
+    case lockfileVersion === 6.0 || lockfileVersion === 6.1:
+      return 'pnpm 8';
+    case lockfileVersion === 7.0 || lockfileVersion === 9.0:
+      return 'pnpm 9';
+    default:
+      return 'not found';
+  }
+}
+
+function shouldUseNpm7(
+  lockfileVersion: number | undefined,
+  nodeVersion: NodeVersion | undefined
+): boolean {
+  if (lockfileVersion === undefined) return false;
+  return lockfileVersion >= 2 && (nodeVersion?.major || 0) < 16;
+}
+
+/**
+ * Helper to get the binary paths that link to the used package manager.
+ * Note: Make sure it doesn't contain any `console.log` calls.
+ */
+export function getPathOverrideForPackageManager({
+  cliType,
+  lockfileVersion,
+  nodeVersion,
+  env,
+}: {
+  cliType: CliType;
+  lockfileVersion: number | undefined;
+  nodeVersion: NodeVersion | undefined;
+  env: { [x: string]: string | undefined };
+}): {
+  /**
+   * Which lockfile was detected.
+   */
+  detectedLockfile: string | undefined;
+  /**
+   * Detected package manager that generated the found lockfile.
+   */
+  detectedPackageManager: string | undefined;
+  /**
+   * Value of $PATH that includes the binaries for the detected package manager.
+   * Undefined if no $PATH are necessary.
+   */
+  path: string | undefined;
+} {
+  const no_override = {
+    detectedLockfile: undefined,
+    detectedPackageManager: undefined,
+    path: undefined,
+  };
+
+  const corepackEnabled = env.ENABLE_EXPERIMENTAL_COREPACK === '1';
+
+  switch (cliType) {
+    case 'npm':
+      switch (true) {
+        case corepackEnabled:
+          return no_override;
+        case shouldUseNpm7(lockfileVersion, nodeVersion):
+          return {
+            path: '/node16/bin-npm7',
+            detectedLockfile: 'package-lock.json',
+            detectedPackageManager: 'npm 7+',
+          };
+        default:
+          return no_override;
+      }
+    case 'pnpm':
+      switch (detectPnpmVersion(lockfileVersion, corepackEnabled)) {
+        case 'corepack_enabled':
+          return no_override;
+        case 'pnpm 7':
+          // pnpm 7
+          return {
+            path: '/pnpm7/node_modules/.bin',
+            detectedLockfile: 'pnpm-lock.yaml',
+            detectedPackageManager: 'pnpm 7',
+          };
+        case 'pnpm 8':
+          // pnpm 8
+          return {
+            path: '/pnpm8/node_modules/.bin',
+            detectedLockfile: 'pnpm-lock.yaml',
+            detectedPackageManager: 'pnpm 8',
+          };
+        case 'pnpm 9':
+          // pnpm 9
+          return {
+            path: '/pnpm9/node_modules/.bin',
+            detectedLockfile: 'pnpm-lock.yaml',
+            detectedPackageManager: 'pnpm 9',
+          };
+        default:
+          return no_override;
+      }
+    case 'bun':
+      switch (true) {
+        case corepackEnabled:
+          return no_override;
+        default:
+          // Bun 1
+          return {
+            path: '/bun1',
+            detectedLockfile: 'bun.lockb',
+            detectedPackageManager: 'Bun',
+          };
+      }
+    case 'yarn':
+      return no_override;
+  }
+}
+
 /**
  * Helper to get the binary paths that link to the used package manager.
  * Note: Make sure it doesn't contain any `console.log` calls.
@@ -622,70 +757,31 @@ export function getPathForPackageManager({
    */
   yarnNodeLinker: string | undefined;
 } {
-  let detectedLockfile: string | undefined;
-  let detectedPackageManager: string | undefined;
-  let pathValue: string | undefined;
-  let yarnNodeLinker: string | undefined;
-  const oldPath = env.PATH + '';
-  const npm7 = '/node16/bin-npm7';
-  const pnpm7 = '/pnpm7/node_modules/.bin';
-  const pnpm8 = '/pnpm8/node_modules/.bin';
-  const bun1 = '/bun1';
-  const corepackEnabled = env.ENABLE_EXPERIMENTAL_COREPACK === '1';
-  if (cliType === 'npm') {
-    if (
-      typeof lockfileVersion === 'number' &&
-      lockfileVersion >= 2 &&
-      (nodeVersion?.major || 0) < 16 &&
-      !oldPath.includes(npm7) &&
-      !corepackEnabled
-    ) {
-      // npm 7
-      pathValue = npm7;
-      detectedLockfile = 'package-lock.json';
-      detectedPackageManager = 'npm 7+';
-    }
-  } else if (cliType === 'pnpm') {
-    if (
-      typeof lockfileVersion === 'number' &&
-      lockfileVersion === 5.4 &&
-      !oldPath.includes(pnpm7) &&
-      !corepackEnabled
-    ) {
-      // pnpm 7
-      pathValue = pnpm7;
-      detectedLockfile = 'pnpm-lock.yaml';
-      detectedPackageManager = 'pnpm 7';
-    } else if (
-      typeof lockfileVersion === 'number' &&
-      lockfileVersion >= 6 &&
-      !oldPath.includes(pnpm8) &&
-      !corepackEnabled
-    ) {
-      // pnpm 8
-      pathValue = pnpm8;
-      detectedLockfile = 'pnpm-lock.yaml';
-      detectedPackageManager = 'pnpm 8';
-    }
-  } else if (cliType === 'bun') {
-    if (!oldPath.includes(bun1) && !corepackEnabled) {
-      // Bun 1
-      pathValue = bun1;
-      detectedLockfile = 'bun.lockb';
-      detectedPackageManager = 'Bun';
-    }
-  } else {
-    // Yarn v2 PnP mode may be activated, so force "node-modules" linker style
-    if (!env.YARN_NODE_LINKER) {
-      yarnNodeLinker = 'node-modules';
-    }
-  }
-  return {
-    detectedLockfile,
-    detectedPackageManager,
-    path: pathValue,
-    yarnNodeLinker,
+  const overrides = getPathOverrideForPackageManager({
+    cliType,
+    lockfileVersion,
+    nodeVersion,
+    env,
+  });
+
+  const alreadyInPath = (newPath: string) => {
+    const oldPath = env.PATH ?? '';
+    return oldPath.split(path.delimiter).includes(newPath);
   };
+
+  switch (true) {
+    case cliType === 'yarn' && !env.YARN_NODE_LINKER:
+      return { ...overrides, yarnNodeLinker: 'node-modules' };
+    case alreadyInPath(overrides.path ?? ''):
+      return {
+        detectedLockfile: undefined,
+        detectedPackageManager: undefined,
+        path: undefined,
+        yarnNodeLinker: undefined,
+      };
+    default:
+      return { ...overrides, yarnNodeLinker: undefined };
+  }
 }
 
 export async function runCustomInstallCommand({

packages/build-utils/test/fixtures/22-pnpm/vercel.json

@@ -4,7 +4,7 @@
   "probes": [
     {
       "path": "/",
-      "mustContain": "pnpm version: 6",
+      "mustContain": "pnpm version: 7",
       "logMustContain": "pnpm run build"
     }
   ]