fix: pnpm support should work on macOS and Linux

Currently we are unable to build applications on macOS and Linux when pnpm is set as package manager. The problem seems to be caused by the way pnpm produces files in node_modules and the way webpack expects them. However, the issue is resolved in case we do not pass `--preserve-symlinks` option to Node.js when starting the webpack process. According to docs (https://pnpm.js.org/en/faq) the preserve-symlinks does not work very well and pnpm does not require it.
So, to resolve the issue, skip the `--preserve-symlinks` option when pnpm is used. To achieve this, introduce a new method in the packageManager that returns the package manager used for the current process.

Author: rosen-vladimirov

lib/constants.ts

@@ -415,3 +415,9 @@ export enum LoggerConfigData {
 }
 
 export const EMIT_APPENDER_EVENT_NAME = "logData";
+
+export enum PackageManagers {
+	npm = "npm",
+	pnpm = "pnpm",
+	yarn = "yarn"
+}

lib/declarations.d.ts

@@ -76,6 +76,12 @@ interface INodePackageManager {
 }
 
 interface IPackageManager extends INodePackageManager {
+	/**
+	 * Gets the name of the package manager used for the current process.
+	 * It can be read from the user settings or by passing -- option.
+	 */
+	getPackageManagerName(): Promise<string>;
+
 	/**
 	 * Gets the version corresponding to the tag for the package
 	 * @param {string} packageName The name of the package.

lib/package-manager.ts

@@ -1,8 +1,10 @@
 
 import { cache, exported, invokeInit } from './common/decorators';
 import { performanceLog } from "./common/decorators";
+import { PackageManagers } from './constants';
 export class PackageManager implements IPackageManager {
 	private packageManager: INodePackageManager;
+	private _packageManagerName: string;
 
 	constructor(
 		private $errors: IErrors,
@@ -19,6 +21,11 @@ export class PackageManager implements IPackageManager {
 		this.packageManager = await this._determinePackageManager();
 	}
 
+	@invokeInit()
+	public async getPackageManagerName(): Promise<string> {
+		return this._packageManagerName;
+	}
+
 	@exported("packageManager")
 	@performanceLog()
 	@invokeInit()
@@ -97,11 +104,14 @@ export class PackageManager implements IPackageManager {
 			this.$errors.fail(`Unable to read package manager config from user settings ${err}`);
 		}
 
-		if (pm === 'yarn' || this.$options.yarn) {
+		if (pm === PackageManagers.yarn || this.$options.yarn) {
+			this._packageManagerName = PackageManagers.yarn;
 			return this.$yarn;
-		} else  if (pm === 'pnpm' || this.$options.pnpm) {
+		} else if (pm === PackageManagers.pnpm || this.$options.pnpm) {
+			this._packageManagerName = PackageManagers.pnpm;
 			return this.$pnpm;
 		} else {
+			this._packageManagerName = PackageManagers.npm;
 			return this.$npm;
 		}
 	}

lib/services/webpack/webpack-compiler-service.ts

@@ -3,7 +3,7 @@ import * as child_process from "child_process";
 import * as semver from "semver";
 import { EventEmitter } from "events";
 import { performanceLog } from "../../common/decorators";
-import { WEBPACK_COMPILATION_COMPLETE, WEBPACK_PLUGIN_NAME } from "../../constants";
+import { WEBPACK_COMPILATION_COMPLETE, WEBPACK_PLUGIN_NAME, PackageManagers } from "../../constants";
 
 export class WebpackCompilerService extends EventEmitter implements IWebpackCompilerService {
 	private webpackProcesses: IDictionary<child_process.ChildProcess> = {};
@@ -18,6 +18,7 @@ export class WebpackCompilerService extends EventEmitter implements IWebpackComp
 		private $logger: ILogger,
 		private $mobileHelper: Mobile.IMobileHelper,
 		private $cleanupService: ICleanupService,
+		private $packageManager: IPackageManager,
 		private $packageInstallationManager: IPackageInstallationManager
 	) { super(); }
 
@@ -155,6 +156,15 @@ export class WebpackCompilerService extends EventEmitter implements IWebpackComp
 		}
 	}
 
+	private async shouldUsePreserveSymlinksOption(projectData: IProjectData): Promise<boolean> {
+		// pnpm does not require symlink (https://github.com/nodejs/node-eps/issues/46#issuecomment-277373566)
+		// and it also does not work in some cases.
+		// Check https://github.com/NativeScript/nativescript-cli/issues/5259 for more information
+		const currentPackageManager = await this.$packageManager.getPackageManagerName();
+		const res = currentPackageManager !== PackageManagers.pnpm;
+		return res;
+	}
+
 	@performanceLog()
 	private async startWebpackProcess(platformData: IPlatformData, projectData: IProjectData, prepareData: IPrepareData): Promise<child_process.ChildProcess> {
 		if (!this.$fs.exists(projectData.webpackConfigPath)) {
@@ -164,18 +174,22 @@ export class WebpackCompilerService extends EventEmitter implements IWebpackComp
 		const envData = this.buildEnvData(platformData.platformNameLowerCase, projectData, prepareData);
 		const envParams = await this.buildEnvCommandLineParams(envData, platformData, projectData, prepareData);
 		const additionalNodeArgs = semver.major(process.version) <= 8 ? ["--harmony"] : [];
+
+		if (await this.shouldUsePreserveSymlinksOption(projectData)) {
+			additionalNodeArgs.push("--preserve-symlinks");
+		}
+
+		if (process.arch === "x64") {
+			additionalNodeArgs.unshift("--max_old_space_size=4096");
+		}
+
 		const args = [
 			...additionalNodeArgs,
-			"--preserve-symlinks",
 			path.join(projectData.projectDir, "node_modules", "webpack", "bin", "webpack.js"),
 			`--config=${projectData.webpackConfigPath}`,
 			...envParams
 		];
 
-		if (process.arch === "x64") {
-			args.unshift("--max_old_space_size=4096");
-		}
-
 		if (prepareData.watch) {
 			args.push("--watch");
 		}

test/services/webpack/webpack-compiler-service.ts

@@ -13,6 +13,9 @@ function getAllEmittedFiles(hash: string) {
 
 function createTestInjector(): IInjector {
 	const testInjector = new Yok();
+	testInjector.register("packageManager", {
+		getPackageManagerName: async () => "npm"
+	});
 	testInjector.register("webpackCompilerService", WebpackCompilerService);
 	testInjector.register("childProcess", {});
 	testInjector.register("hooksService", {});