Use Yarn 2

.circleci/config.yml

@@ -1,25 +1,13 @@
 version: 2.1
 
 aliases:
-  - &restore-node-modules-cache
-    keys:
-      - v1-yarn-deps-{{ checksum "yarn.lock" }}
-      - v1-yarn-deps-
-
   - &restore-yarn-cache
-    keys:
-      - v1-1-yarn-cache-{{ checksum "yarn.lock" }}
-      - v1-1-yarn-cache-
-
-  - &save-node-modules-cache
-    paths:
-      - node_modules
-    key: v1-yarn-deps-{{ checksum "yarn.lock" }}
+    key: v2-yarn-cache-{{ checksum "yarn.lock" }}
 
   - &save-yarn-cache
     paths:
-      - ~/.cache/yarn
-    key: v1-1-yarn-cache-{{ checksum "yarn.lock" }}
+      - ~/.yarn/berry/cache
+    key: v2-yarn-cache-{{ checksum "yarn.lock" }}
 
   - &artifact_babel
     path: ~/babel/packages/babel-standalone/babel.js
@@ -56,7 +44,6 @@ jobs:
     steps:
       - checkout
       - restore_cache: *restore-yarn-cache
-      - restore_cache: *restore-node-modules-cache
         # Builds babel-standalone with the regular Babel config
         # test-ci-coverage doesn't test babel-standalone, as trying to gather coverage
       - run: IS_PUBLISH=true make -j build-standalone-ci
@@ -65,7 +52,6 @@ jobs:
       - run: yarn jest "\-standalone/test"
       - store_artifacts: *artifact_babel
       - store_artifacts: *artifact_babel_min
-      - save_cache: *save-node-modules-cache
       - save_cache: *save-yarn-cache
 
   test262:
@@ -81,7 +67,6 @@ jobs:
               git checkout -qf FETCH_HEAD
             fi
       - restore_cache: *restore-yarn-cache
-      - restore_cache: *restore-node-modules-cache
       - run:
           name: Build Babel
           command: BABEL_ENV=test make bootstrap
@@ -121,20 +106,20 @@ jobs:
             cat ~/diff.tap | $(npm bin)/tap-merge | $(npm bin)/tap-mocha-reporter xunit | tee ~/test-results/test262/results.xml
           <<: *test262_workdir
       - store_test_results: *artifact_test262_xunit
+      - save_cache: *save-yarn-cache
 
   publish-verdaccio:
     executor: node-executor
     steps:
       - checkout
       - restore_cache: *restore-yarn-cache
-      - restore_cache: *restore-node-modules-cache
-      - run: yarn install
       - run: ./scripts/integration-tests/publish-local.sh
       - persist_to_workspace:
           root: /tmp/verdaccio-workspace
           paths:
             - storage
             - htpasswd
+      - save_cache: *save-yarn-cache
 
   e2e-babel:
     executor: node-executor

.codesandbox/ci.json

@@ -1,6 +1,5 @@
 {
-  "installCommand": "codesandbox",
-  "buildCommand": false,
+  "buildCommand": "codesandbox:build",
   "sandboxes": ["7s08o", "vhm64"],
   "packages": ["packages/*"]
 }

.travis.yml

@@ -1,14 +1,16 @@
 git:
   depth: 5
 language: node_js
+
 cache:
-  yarn: true
+  npm: false
+  directories:
+    - ~/.yarn/berry/cache
 
 os: linux
 
 env:
   global:
-    - PATH=$HOME/.yarn/bin:$PATH
     - JOB=test
 
 install: skip
@@ -37,13 +39,13 @@ matrix:
         # https://travis-ci.community/t/build-doesnt-finish-after-completing-tests/288/9
         - YARN_GPG=no
       cache:
-        yarn: true
+        npm: false
         directories:
           - $HOME/AppData/Local/Temp/chocolatey
+          - $HOME/AppData/Local/Yarn/Berry/cache
     # Continue node_js matrix
     - node_js: "12"
     - node_js: "10"
-    # Node.js 6 and 8 are tested on GitHub actions
     - node_js: "node"
       env: JOB=babel-parser-flow-tests
     - node_js: "node"

.yarn-patches/@lerna/npm-publish.patch

@@ -0,0 +1,31 @@
+diff --git a/npm-publish.js b/npm-publish.js
+index ee6ad133e..6a31d1775 100644
+--- a/npm-publish.js
++++ b/npm-publish.js
+@@ -32,6 +32,15 @@ const PublishConfig = figgyPudding(
+   }
+ );
+
++function stripWorkspaceProtocolFromDeps(deps) {
++  if (!deps) return;
++  for (const [name, version] of Object.entries(deps)) {
++    if (version.startsWith("workspace:")) {
++      deps[name] = version.slice(10);
++    }
++  }
++}
++
+ function npmPublish(pkg, tarFilePath, _opts, otpCache) {
+   const { scope } = npa(pkg.name);
+   // pass only the package scope to libnpmpublish
+@@ -67,6 +76,10 @@ function npmPublish(pkg, tarFilePath, _opts, otpCache) {
+         manifest.publishConfig.tag = opts.tag;
+       }
+
++      stripWorkspaceProtocolFromDeps(manifest.dependencies);
++      stripWorkspaceProtocolFromDeps(manifest.peerDependencies);
++      stripWorkspaceProtocolFromDeps(manifest.devDependencies);
++
+       return otplease(innerOpts => publish(manifest, tarData, innerOpts), opts, otpCache).catch(err => {
+         opts.log.silly("", err);
+         opts.log.error(err.code, (err.body && err.body.error) || err.message);

.yarn-patches/@lerna/pack-directory.patch

@@ -0,0 +1,92 @@
+diff --git a/lib/pack-directory.js b/lib/pack-directory.js
+index d46069c78..2ba6bfea1 100644
+--- a/lib/pack-directory.js
++++ b/lib/pack-directory.js
+@@ -2,13 +2,13 @@
+
+ const path = require("path");
+ const figgyPudding = require("figgy-pudding");
+-const packlist = require("npm-packlist");
+ const log = require("npmlog");
+-const tar = require("tar");
+ const tempWrite = require("temp-write");
+ const getPacked = require("@lerna/get-packed");
+ const Package = require("@lerna/package");
+ const runLifecycle = require("@lerna/run-lifecycle");
++const util = require("util");
++const exec = util.promisify(require('child_process').exec);
+
+ module.exports = packDirectory;
+
+@@ -40,34 +40,23 @@ function packDirectory(_pkg, dir, _opts) {
+     chain = chain.then(() => pkg.refresh());
+   }
+
+-  chain = chain.then(() => runLifecycle(pkg, "prepack", opts));
+-  chain = chain.then(() => pkg.refresh());
+-  chain = chain.then(() => packlist({ path: pkg.contents }));
+-  chain = chain.then(files =>
+-    tar.create(
+-      {
+-        cwd: pkg.contents,
+-        prefix: "package/",
+-        portable: true,
+-        // Provide a specific date in the 1980s for the benefit of zip,
+-        // which is confounded by files dated at the Unix epoch 0.
+-        mtime: new Date("1985-10-26T08:15:00.000Z"),
+-        gzip: true,
+-      },
+-      // NOTE: node-tar does some Magic Stuff depending on prefixes for files
+-      //       specifically with @ signs, so we just neutralize that one
+-      //       and any such future "features" by prepending `./`
+-      files.map(f => `./${f}`)
+-    )
++  // We need to call "yarn pack" to remove the "workspace:" protocol from
++  // package.json before publishing
++  chain = chain.then(() => tempWrite("", getTarballName(pkg)));
++  chain = chain.then(tarFilePath =>
++    exec("yarn pack --out " + tarFilePath, { cwd: pkg.location })
++      .then(({ stdout, stderr }) => {
++        const err = stderr.toString();
++        if (err) console.log(err);
++      })
++      .then(() => tarFilePath)
+   );
+-  chain = chain.then(stream => tempWrite(stream, getTarballName(pkg)));
+   chain = chain.then(tarFilePath =>
+-    getPacked(pkg, tarFilePath).then(packed =>
+-      Promise.resolve()
+-        .then(() => runLifecycle(pkg, "postpack", opts))
+-        .then(() => packed)
+-    )
++    Promise.resolve()
++      .then(() => pkg.refresh())
++      .then(() => tarFilePath)
+   );
++  chain = chain.then(tarFilePath => getPacked(pkg, tarFilePath));
+
+   return chain;
+ }
+@@ -81,3 +70,7 @@ function getTarballName(pkg) {
+
+   return `${name}-${pkg.version}.tgz`;
+ }
++
++function tap(fn) {
++  return arg => Promise.resolve(fn(arg)).then(() => arg);
++}
+\ No newline at end of file
+diff --git a/package.json b/package.json
+index e00ac73ff..953512b2c 100644
+--- a/package.json
++++ b/package.json
+@@ -31,9 +31,7 @@
+     "@lerna/package": "3.16.0",
+     "@lerna/run-lifecycle": "3.16.2",
+     "figgy-pudding": "^3.5.1",
+-    "npm-packlist": "^1.4.4",
+     "npmlog": "^4.1.2",
+-    "tar": "^4.4.10",
+     "temp-write": "^3.4.0"
+   },
+   "gitHead": "bb048cb306b5cfcb039aa98f667cf3751cf0ad20"

.yarn-patches/@lerna/package-graph.patch

@@ -0,0 +1,24 @@
+diff --git a/index.js b/index.js
+index f860af4d2..27c4ce21d 100644
+--- a/index.js
++++ b/index.js
+@@ -57,8 +57,18 @@ class PackageGraph extends Map {
+         // Yarn decided to ignore https://github.com/npm/npm/pull/15900 and implemented "link:"
+         // As they apparently have no intention of being compatible, we have to do it for them.
+         // @see https://github.com/yarnpkg/yarn/issues/4212
+-        const spec = graphDependencies[depName].replace(/^link:/, "file:");
++        let spec = graphDependencies[depName].replace(/^link:/, "file:");
++
++        // npa doesn't support the explicit workspace: protocol, supported by
++        // pnpm and Yarn.
++        // https://github.com/lerna/lerna/pull/2450
++        const explicitWorkspace = /^workspace:/.test(spec);
++        if (explicitWorkspace) {
++          spec = spec.replace(/^workspace:/, "");
++        }
++
+         const resolved = npa.resolve(depName, spec, currentNode.location);
++        resolved.explicitWorkspace = explicitWorkspace;
+
+         if (!depNode) {
+           // it's an external dependency, store the resolution and bail

.yarn-patches/@lerna/package.patch

@@ -0,0 +1,16 @@
+diff --git a/index.js b/index.js
+index 67b997073..6e2912e9e 100644
+--- a/index.js
++++ b/index.js
+@@ -209,6 +209,11 @@ class Package {
+     if (resolved.registry || resolved.type === "directory") {
+       // a version (1.2.3) OR range (^1.2.3) OR directory (file:../foo-pkg)
+       depCollection[depName] = `${savePrefix}${depVersion}`;
++
++      // https://github.com/lerna/lerna/pull/2450
++      if (resolved.explicitWorkspace) {
++        depCollection[depName] = `workspace:${depCollection[depName]}`;
++      }
+     } else if (resolved.gitCommittish) {
+       // a git url with matching committish (#v1.2.3 or #1.2.3)
+       const [tagPrefix] = /^\D*/.exec(resolved.gitCommittish);

.yarn-patches/@lerna/version.patch

@@ -0,0 +1,17 @@
+diff --git a/command.js b/command.js
+index 4109ff1db..86349e057 100644
+--- a/command.js
++++ b/command.js
+@@ -12,6 +12,12 @@ exports.describe = "Bump version of packages changed since the last release.";
+
+ exports.builder = (yargs, composed) => {
+   const opts = {
++    // THIS IS ONLY USED BY BABEL
++    "exclude-dependents": {
++      describe: "Exclude all transitive dependents.",
++      type: "boolean"
++    },
++
+     "allow-branch": {
+       describe: "Specify which branches to allow versioning from.",
+       type: "array",

.yarn/plugins/@yarnpkg/plugin-deduplicate.cjs

@@ -0,0 +1,11 @@
+/* eslint-disable */
+module.exports = {
+name: "@yarnpkg/plugin-deduplicate",
+factory: function (require) {
+var plugin;plugin=(()=>{"use strict";var e={587:(e,t,r)=>{r.r(t),r.d(t,{default:()=>d});var o=r(594),s=r(966),a=r(42),n=r(513),i=function(e,t,r,o){var s,a=arguments.length,n=a<3?t:null===o?o=Object.getOwnPropertyDescriptor(t,r):o;if("object"==typeof Reflect&&"function"==typeof Reflect.decorate)n=Reflect.decorate(e,t,r,o);else for(var i=e.length-1;i>=0;i--)(s=e[i])&&(n=(a<3?s(n):a>3?s(t,r,n):s(t,r))||n);return a>3&&n&&Object.defineProperty(t,r,n),n};class c extends o.BaseCommand{async execute(){const e=await s.Configuration.find(this.context.cwd,this.context.plugins),{project:t}=await s.Project.find(e,this.context.cwd);await t.restoreInstallState();const r=await s.StreamReport.start({configuration:e,stdout:this.context.stdout,includeFooter:!1},async e=>{e.startTimerSync("deduplication step",()=>{!function(e,t){const r=new Map;for(const[t,o]of e.storedResolutions.entries()){const s=o,a=e.storedDescriptors.get(t).identHash,n=r.get(a);void 0===n?r.set(a,new Set([s])):r.set(a,n.add(s))}for(const o of e.storedResolutions.keys()){const a=e.storedDescriptors.get(o),i=r.get(a.identHash),c=a.range.match(/^npm:(.*)$/);if(null!==c&&(void 0!==i&&i.size>1)){const r=Array.from(i).map(t=>{const r=e.storedPackages.get(t);if(void 0===r)throw new TypeError(`Can't find package for locator hash '${t}'`);if(s.structUtils.isVirtualLocator(r)){const t=s.structUtils.devirtualizeLocator(r);return e.storedPackages.get(t.locatorHash)}return r}).filter(e=>null!==e.version&&n.satisfies(e.version,c[1])).sort((e,t)=>n.gt(e.version,t.version)?-1:1);if(r.length>1){const n=r[0].locatorHash,i=e.storedResolutions.get(o),c=e.storedPackages.get(n),d=e.storedPackages.get(i);!1===s.structUtils.areLocatorsEqual(d,c)&&(t.reportInfo(s.MessageName.UNNAMED,`${s.structUtils.stringifyDescriptor(a)} can be deduplicated from ${d.name}@${d.version} to ${c.name}@${c.version}`),e.storedResolutions.set(o,n))}}}}
+/**
+ * @license MIT
+ */(t,e)})});if(r.hasErrors())return r.exitCode();const o=await s.Cache.find(e);return(await s.StreamReport.start({configuration:e,stdout:this.context.stdout,includeLogs:!0},async e=>{await t.install({cache:o,report:e})})).exitCode()}}c.usage=a.Command.Usage({category:"Workspace-related commands",description:"Reduces dependencies with overlapping ranges to a smaller set of packages",details:"https://github.com/atlassian/yarn-deduplicate for yarn v2",examples:[]}),i([a.Command.Path("deduplicate")],c.prototype,"execute",null);const d={commands:[c]}},594:e=>{e.exports=require("@yarnpkg/cli")},966:e=>{e.exports=require("@yarnpkg/core")},42:e=>{e.exports=require("clipanion")},513:e=>{e.exports=require("semver")}},t={};function r(o){if(t[o])return t[o].exports;var s=t[o]={exports:{}};return e[o](s,s.exports,r),s.exports}return r.d=(e,t)=>{for(var o in t)r.o(t,o)&&!r.o(e,o)&&Object.defineProperty(e,o,{enumerable:!0,get:t[o]})},r.o=(e,t)=>Object.prototype.hasOwnProperty.call(e,t),r.r=e=>{"undefined"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:"Module"}),Object.defineProperty(e,"__esModule",{value:!0})},r(587)})();
+return plugin;
+}
+};

.yarnrc

@@ -0,0 +1,3 @@
+# Use Yarn 2
+# This path should always match the one in .yarnrc.yml
+yarn-path ".yarn/releases/yarn-2.1.1.cjs"

.yarnrc.yml

@@ -0,0 +1,14 @@
+enableGlobalCache: true
+
+enableTransparentWorkspaces: false
+
+nodeLinker: node-modules
+
+plugins:
+  - path: .yarn/plugins/@yarnpkg/plugin-deduplicate.cjs
+    spec: "https://raw.githubusercontent.com/eps1lon/yarn-plugin-deduplicate/latest/bin/%40yarnpkg/plugin-deduplicate.js"
+
+unsafeHttpWhitelist:
+  - localhost
+
+yarnPath: .yarn/releases/yarn-2.1.1.cjs

Gulpfile.js

@@ -140,17 +140,9 @@ function buildRollup(packages) {
               rollupNodeResolve({
                 browser: nodeResolveBrowser,
                 preferBuiltins: true,
-                //todo: When Yarn workspaces is enabled, remove `dedupe` option
+                //todo: remove when semver and source-map are bumped to latest versions
                 dedupe(importee) {
-                  return (
-                    importee.startsWith("lodash/") ||
-                    [
-                      "babel-plugin-dynamic-import-node/utils",
-                      "esutils",
-                      "semver",
-                      "source-map",
-                    ].includes(importee)
-                  );
+                  return ["semver", "source-map"].includes(importee);
                 },
               }),
               rollupCommonJs({