WIP: feat(type): add support for new link: dependency type

__tests__/commands/install/integration.js

@@ -61,6 +61,32 @@ test.concurrent('properly find and save build artifacts', async () => {
   });
 });
 
+test.concurrent('creates a symlink to a directory when using the link: protocol', async () => {
+  await runInstall({}, 'install-link', async (config): Promise<void> => {
+    const expectPath = path.join(config.cwd, 'node_modules', 'test-absolute');
+    expect(await fs.exists(expectPath)).toEqual(true);
+
+    const stat = await fs.stat(expectPath);
+    expect(stat.isLink()).toEqual(true);
+
+    const target = await fs.readlink(expectPath);
+    expect(target).toEqual('/some-test-path');
+  });
+});
+
+test.concurrent('resolves the symlinks relative to the package path when using the link: protocol; not the node_modules', async () => {
+  await runInstall({}, 'install-link', async (config): Promise<void> => {
+    const expectPath = path.join(config.cwd, 'node_modules', 'test-relative');
+    expect(await fs.exists(expectPath)).toEqual(true);
+
+    const stat = await fs.stat(expectPath);
+    expect(stat.isLink()).toEqual(true);
+
+    const target = await fs.readlink(expectPath);
+    expect(target).toEqual('../some-test-path');
+  });
+});
+
 test('changes the cache path when bumping the cache version', async () => {
   await runInstall({}, 'install-github', async (config): Promise<void> => {
     const inOut = new stream.PassThrough();

src/config.js

@@ -31,6 +31,7 @@ export type ConfigOptions = {
   preferOffline?: boolean,
   pruneOfflineMirror?: boolean,
   enableMetaFolder?: boolean,
+  linkFileDependencies?: boolean,
   captureHar?: boolean,
   ignoreScripts?: boolean,
   ignorePlatform?: boolean,
@@ -90,7 +91,11 @@ export default class Config {
   offline: boolean;
   preferOffline: boolean;
   pruneOfflineMirror: boolean;
+<<<<<<< HEAD
   enableMetaFolder: boolean;
+=======
+  linkFileDependencies: boolean;
+>>>>>>> Makes the link-file-dependencies configurable via the yarnrc
   disableLockfileVersions: boolean;
   ignorePlatform: boolean;
   binLinks: boolean;
@@ -262,7 +267,11 @@ export default class Config {
     this.workspacesExperimental = Boolean(this.getOption('workspaces-experimental'));
 
     this.pruneOfflineMirror = Boolean(this.getOption('yarn-offline-mirror-pruning'));
+<<<<<<< HEAD
     this.enableMetaFolder = Boolean(this.getOption('enable-meta-folder'));
+=======
+    this.linkFileDependencies = Boolean(this.getOption('yarn-link-file-dependencies'));
+>>>>>>> Makes the link-file-dependencies configurable via the yarnrc
     this.disableLockfileVersions = Boolean(this.getOption('yarn-disable-lockfile-versions'));
 
     //init & create cacheFolder, tempFolder

src/fetchers/index.js

@@ -12,4 +12,4 @@ export {TarballFetcher as tarball};
 
 export type Fetchers = BaseFetcher | CopyFetcher | GitFetcher | TarballFetcher;
 
-export type FetcherNames = 'base' | 'copy' | 'git' | 'tarball';
+export type FetcherNames = 'base' | 'copy' | 'git' | 'link' | 'tarball';

src/package-fetcher.js

@@ -1,6 +1,6 @@
 /* @flow */
 
-import type {FetchedMetadata} from './types.js';
+import type {Manifest, FetchedMetadata} from './types.js';
 import type PackageResolver from './package-resolver.js';
 import type {Fetchers} from './fetchers/index.js';
 import type {Reporter} from './reporters/index.js';
@@ -37,6 +37,13 @@ export default class PackageFetcher {
     const dest = this.config.generateHardModulePath(ref);
 
     const remote = ref.remote;
+
+    // Mock metedata for linked dependencies
+    if (remote.type === 'link') {
+      const mockPkg: Manifest = {_uid: '', name: '', version: '0.0.0'};
+      return Promise.resolve({resolved: null, hash: '', dest, package: mockPkg, cached: false});
+    }
+
     const Fetcher = fetchers[remote.type];
     if (!Fetcher) {
       throw new MessageError(this.reporter.lang('unknownFetcherFor', remote.type));

src/package-linker.js

@@ -140,15 +140,20 @@ export default class PackageLinker {
     const hardlinksEnabled = linkDuplicates && (await fs.hardlinksWork(this.config.cwd));
 
     const copiedSrcs: Map<string, string> = new Map();
-    for (const [dest, {pkg, loc: src}] of flatTree) {
+    for (const [dest, {pkg, loc}] of flatTree) {
+      const remote = pkg._remote || {type: ''};
       const ref = pkg._reference;
+      const src = remote.type === 'link' ? remote.reference : loc;
       invariant(ref, 'expected package reference');
       ref.setLocation(dest);
 
       // backwards compatibility: get build artifacts from metadata
-      const metadata = await this.config.readPackageMetadata(src);
-      for (const file of metadata.artifacts) {
-        artifactFiles.push(path.join(dest, file));
+      // does not apply to linked dependencies
+      if (remote.type !== 'link') {
+        const metadata = await this.config.readPackageMetadata(src);
+        for (const file of metadata.artifacts) {
+          artifactFiles.push(path.join(dest, file));
+        }
       }
 
       const integrityArtifacts = this.artifacts[`${pkg.name}@${pkg.version}`];
@@ -166,6 +171,7 @@ export default class PackageLinker {
         copyQueue.set(dest, {
           src,
           dest,
+          type: remote.type,
           onFresh() {
             if (ref) {
               ref.setFresh(true);

src/resolvers/exotics/file-resolver.js

@@ -2,6 +2,7 @@
 
 import type {Manifest} from '../../types.js';
 import type PackageRequest from '../../package-request.js';
+import type {RegistryNames} from '../../registries/index.js';
 import {MessageError} from '../../errors.js';
 import ExoticResolver from './exotic-resolver.js';
 import * as util from '../../util/misc.js';
@@ -30,6 +31,19 @@ export default class FileResolver extends ExoticResolver {
     if (!path.isAbsolute(loc)) {
       loc = path.join(this.config.cwd, loc);
     }
+
+    if (this.config.linkFileDependencies) {
+      const registry: RegistryNames = 'npm';
+      const manifest: Manifest = {_uid: '', name: '', version: '0.0.0', _registry: registry};
+      manifest._remote = {
+        type: 'link',
+        registry,
+        hash: null,
+        reference: loc,
+      };
+      manifest._uid = manifest.version;
+      return manifest;
+    }
     if (!await fs.exists(loc)) {
       throw new MessageError(this.reporter.lang('doesntExist', loc));
     }

src/resolvers/exotics/link-resolver.js

@@ -0,0 +1,41 @@
+/* @flow */
+
+import type {Manifest} from '../../types.js';
+import type {RegistryNames} from '../../registries/index.js';
+import type PackageRequest from '../../package-request.js';
+import ExoticResolver from './exotic-resolver.js';
+import * as util from '../../util/misc.js';
+
+const path = require('path');
+
+export default class LinkResolver extends ExoticResolver {
+  constructor(request: PackageRequest, fragment: string) {
+    super(request, fragment);
+    this.loc = util.removePrefix(fragment, 'link:');
+  }
+
+  loc: string;
+
+  static protocol = 'link';
+
+  resolve(): Promise<Manifest> {
+    let loc = this.loc;
+    if (!path.isAbsolute(loc)) {
+      loc = path.join(this.config.cwd, loc);
+    }
+
+    const registry: RegistryNames = 'npm';
+    const manifest: Manifest = {_uid: '', name: '', version: '0.0.0', _registry: registry};
+
+    manifest._remote = {
+      type: 'link',
+      registry,
+      hash: null,
+      reference: loc,
+    };
+
+    manifest._uid = manifest.version;
+
+    return Promise.resolve(manifest);
+  }
+}

src/resolvers/index.js

@@ -14,6 +14,7 @@ import ExoticGit from './exotics/git-resolver.js';
 import ExoticTarball from './exotics/tarball-resolver.js';
 import ExoticGitHub from './exotics/github-resolver.js';
 import ExoticFile from './exotics/file-resolver.js';
+import ExoticLink from './exotics/link-resolver.js';
 import ExoticGitLab from './exotics/gitlab-resolver.js';
 import ExoticGist from './exotics/gist-resolver.js';
 import ExoticBitbucket from './exotics/bitbucket-resolver.js';
@@ -23,6 +24,7 @@ export const exotics = {
   tarball: ExoticTarball,
   github: ExoticGitHub,
   file: ExoticFile,
+  link: ExoticLink,
   gitlab: ExoticGitLab,
   gist: ExoticGist,
   bitbucket: ExoticBitbucket,

src/util/fs.js

@@ -42,6 +42,7 @@ const noop = () => {};
 export type CopyQueueItem = {
   src: string,
   dest: string,
+  type?: string,
   onFresh?: ?() => void,
   onDone?: ?() => void,
 };
@@ -159,11 +160,23 @@ async function buildActionsForCopy(
 
   //
   async function build(data): Promise<void> {
-    const {src, dest} = data;
+    const {src, dest, type} = data;
     const onFresh = data.onFresh || noop;
     const onDone = data.onDone || noop;
     files.add(dest);
 
+    if (type === 'link') {
+      await mkdirp(path.dirname(dest));
+      onFresh();
+      actions.push({
+        type: 'symlink',
+        dest,
+        linkname: src,
+      });
+      onDone();
+      return;
+    }
+
     if (events.ignoreBasenames.indexOf(path.basename(src)) >= 0) {
       // ignored file
       return;