v7.0.0-alpha.20

Handle cycles of plugins compiling themselves and .babelrc.js files loading themselves

.babelrc.js

@@ -6,12 +6,28 @@ let envOpts = {
 
 module.exports = {
   comments: false,
+  plugins: [
+    // temp until next release
+    function() {
+      return {
+        visitor: {
+          "Function": function(path) {
+            const node = path.node;
+            for (let i = 0; i < node.params.length; i++) {
+              const param = node.params[i];
+              if (param.type === "AssignmentPattern") {
+                param.left.optional = false;
+              }
+            }
+          }
+        }
+      };
+    }
+  ],
   presets: [
-    [
-      "env", envOpts
-    ],
+    ["env", envOpts],
     "stage-0",
-    "flow",
+    "flow"
   ],
   env: {
     cov: {
@@ -21,9 +37,9 @@ module.exports = {
   }
 };
 
-if (process.env.BABEL_ENV === 'development') {
+if (process.env.BABEL_ENV === "development") {
   envOpts.targets = {
     node: "current"
   };
   envOpts.debug = true;
-};
+}

.eslintignore

@@ -7,3 +7,9 @@ packages/*/lib
 packages/*/dist
 packages/*/test/fixtures
 packages/*/test/tmp
+packages/babel-standalone/babel.js
+packages/babel-standalone/babel.min.js
+
+# Prettier tries to insert trailing commas in function calls, which Node.js
+# doesn't natively support. This causes an error when loading the Gulp tasks.
+packages/babel-standalone/src/gulpTasks.js

.flowconfig

@@ -13,6 +13,5 @@ lib/types.js
 lib/third-party-libs.js.flow
 
 [options]
-strip_root=true
 suppress_comment= \\(.\\|\n\\)*\\$FlowFixMe
 suppress_comment= \\(.\\|\n\\)*\\$FlowIssue

.github/PULL_REQUEST_TEMPLATE.md

@@ -2,20 +2,19 @@
 Before making a PR please make sure to read our contributing guidelines 
 https://github.com/babel/babel/blob/master/CONTRIBUTING.md
 
-For any issue references: Add a comma-separated list of a [closing word](https://help.github.com/articles/closing-issues-via-commit-messages/) followed by the ticket number fixed by the PR
+For any issue references: Add a comma-separated list of a [closing word](https://help.github.com/articles/closing-issues-via-commit-messages/) followed by the ticket number fixed by the PR. It should be underlined in the preview if done correctly.
 -->
 
-| Q                        | A <!--(yes/no) -->
+| Q                        | A <!--(can use an emoji 👍 ) -->
 | ------------------------ | ---
+| Fixed Issues             | `Fixes #1, Fixes #2` <!-- rm the quotes to link the issues -->
 | Patch: Bug Fix?          | 
 | Major: Breaking Change?  | 
 | Minor: New Feature?      | 
-| Deprecations?            | 
-| Spec Compliancy?         | 
 | Tests Added/Pass?        | 
-| Fixed Tickets            | `Fixes #1, Fixes #2` <!-- rm the quotes to link the issues -->
+| Spec Compliancy?         | 
 | License                  | MIT
-| Doc PR                   | <!-- if yes, add `[skip ci]` to your commit message to skip CI builds -->
-| Dependency Changes       | 
+| Doc PR                   | <!-- if yes, can add `[skip ci]` to your commit message to skip CI builds -->
+| Any Dependency Changes?  | 
 
 <!-- Describe your changes below in as much detail as possible -->

.gitignore

@@ -22,6 +22,10 @@ package-lock.json
 /packages/babel-runtime/helpers/es6/*.js
 !/packages/babel-runtime/helpers/es6/toArray.js
 /packages/babel-register/test/.babel
+/packages/babel-cli/test/tmp
+/packages/babel-node/test/tmp
 /packages/*/lib
 .nyc_output
 /babel.sublime-workspace
+packages/babel-standalone/babel.js
+packages/babel-standalone/babel.min.js

.travis.yml

@@ -12,9 +12,17 @@ node_js:
   - '4'
 
 env:
-  - JOB=test
+  global:
+    - PATH=$HOME/.yarn/bin:$PATH
+    - JOB=test
+
+before_install:
+  - curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version 0.28.1
 
 script:
+  # Babel doesn't build correctly with npm v2 (which comes bundled with Node v4)
+  # so we manually upgrade to a known working npm version.
+  - npm install --global npm@4
   - 'if [ "$JOB" = "test" ]; then make test-ci; fi'
   - 'if [ "$JOB" = "lint" ]; then make lint && make flow; fi'
 

.yarnrc

@@ -0,0 +1 @@
+workspaces-experimental true

CONTRIBUTING.md

@@ -31,6 +31,8 @@ Contributions are always welcome, no matter how large or small.
  - Check out [the Babel Plugin Handbook](https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md#babel-plugin-handbook) - core plugins are written the same way as any other plugin!
  - Check out [AST Explorer](http://astexplorer.net/#/scUfOmVOG5) to learn more about ASTs or make your own plugin in the browser
 - When you feel ready to jump into the Babel source code, a good place to start is to look for issues tagged with [help-wanted](https://github.com/babel/babel/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) and/or [beginner-friendly](https://github.com/babel/babel/issues?q=is%3Aissue+is%3Aopen+label%3A%22beginner-friendly%22).
+- Follow along with what we are working on by joining our Slack, following our annoucements on [Twitter](https://twitter.com/babeljs), and reading (or participating!) in our [meeting notes](https://github.com/babel/notes).
+- Check out our [website](http://babeljs.io/) and the [repo](https://github.com/babel/website)
 
 ## Chat
 
@@ -40,11 +42,9 @@ Feel free to check out the `#discussion`/`#development` channels on our [Slack](
 
 **Note:** Versions `< 5.1.10` can't be built.
 
-Babel is built for Node.js 4 and up but we develop using Node.js 6. Make sure you are on npm 3.
+Babel is built for Node 4 and up but we develop using Node 8 and yarn. You can check this with `node -v`.
 
-You can check this with `node -v` and `npm -v`.
-
-In addition, make sure that Yarn is installed.
+Make sure that Yarn is installed with version >= `0.28.0`.
 Installation instructions can be found here: https://yarnpkg.com/en/docs/install.
 
 ### Setup
@@ -114,12 +114,25 @@ To run tests for a specific package in [packages](https://github.com/babel/babel
 $ TEST_ONLY=babel-cli make test
 ```
 
+`TEST_ONLY` will also match substrings of the package name:
+
+```sh
+# Run tests for the babel-plugin-transform-es2015-classes package.
+$ TEST_ONLY=es2015-class make test
+```
+
 Use the `TEST_GREP` variable to run a subset of tests by name:
 
 ```sh
 $ TEST_GREP=transformation make test
 ```
 
+Substitute spaces for hyphens and forward slashes when targeting specific test names:
+
+```sh
+$ TEST_GREP="arrow functions destructuring parameters" make test
+```
+
 To enable the Node.js debugger added in v6.3.0, set the `TEST_DEBUG` environment variable:
 
 ```sh
@@ -138,15 +151,15 @@ $ ./scripts/test-cov.sh
 
 #### Troubleshooting Tests
 
-In case you're not able to reproduce an error on CI locally, it may be due to 
+In case you're not able to reproduce an error on CI locally, it may be due to
 
  - Node Version: Travis CI runs the tests against all major node versions. If your tests use JavaScript features unsupported by lower versions of node, then use [minNodeVersion option](#writing-tests) in options.json.
  - Timeout: Check the CI log and if the only errors are timeout errors and you are sure that it's not related to the changes you made, ask someone in the slack channel to trigger rebuild on the CI build and it might be resolved
- 
+
 In case you're locally getting errors which are not on the CI, it may be due to
 
  - Updates in Dependencies: Make sure you run `make bootstrap` before you run `make build` or `make watch` before you run the tests.
- 
+
 ### Writing tests
 
 Most packages in [`/packages`](https://github.com/babel/babel/tree/master/packages) have a `test` folder, however some tests might be in other packages or in [`/packages/babel-core`](https://github.com/babel/babel/tree/master/packages/babel-core/test/fixtures).
@@ -261,7 +274,7 @@ To start the debugging in Chrome DevTools, open the given URL.
 The debugger starts at the first executed line of code, which is Mocha's first line by default.
 Click _Resume script execution_ <img src="https://i.imgur.com/TmYBn9d.png" alt="Resume script execution button." width="16"> to jump to the set breakpoint.
 Note that the code shown in Chrome DevTools is compiled code and therefore differs.
- 
+
 ## Internals
 - AST spec ([babylon/ast/spec.md](https://github.com/babel/babylon/blob/master/ast/spec.md))
 - Versioning ([doc/design/versioning.md](https://github.com/babel/babel/blob/master/doc/design/versioning.md)

Makefile

@@ -8,7 +8,14 @@ export FORCE_COLOR = true
 .PHONY: build build-dist watch lint fix clean test-clean test-only test test-ci publish bootstrap
 
 build: clean
+	rm -rf packages/*/lib
 	./node_modules/.bin/gulp build
+ifneq ($(BABEL_ENV), "cov")
+	make build-standalone
+endif
+
+build-standalone:
+	./node_modules/.bin/gulp build-babel-standalone --cwd=packages/babel-standalone/
 
 build-dist: build
 	cd packages/babel-polyfill; \
@@ -22,13 +29,13 @@ watch: clean
 	BABEL_ENV=development ./node_modules/.bin/gulp watch
 
 lint:
-	./node_modules/.bin/eslint scripts packages *.js --format=codeframe
+	./node_modules/.bin/eslint scripts packages *.js --format=codeframe --rulesdir="./eslint_rules"
 
 flow:
-	./node_modules/.bin/flow check
+	./node_modules/.bin/flow check --strip-root
 
 fix:
-	./node_modules/.bin/eslint scripts packages *.js --format=codeframe --fix
+	./node_modules/.bin/eslint scripts packages *.js --format=codeframe --fix --rulesdir="./eslint_rules"
 
 clean: test-clean
 	rm -rf packages/babel-polyfill/browser*
@@ -46,6 +53,8 @@ clean-all:
 	rm -rf packages/*/lib
 	rm -rf node_modules
 	rm -rf packages/*/node_modules
+	rm -rf package-lock.json
+	rm -rf packages/*/package-lock.json
 	make clean
 
 test-only:

README.md

@@ -77,7 +77,7 @@ https://phabricator.babeljs.io/T2168 mostly corresponds to https://github.com/ba
 
 ## Want to report an issue with [babeljs.io](https://babeljs.io) (the website)?
 
-For documentation and website issues please visit the [babel/babel.github.io](https://github.com/babel/babel.github.io) repo.
+For documentation and website issues please visit the [babel/website](https://github.com/babel/website) repo.
 
 ## Want to contribute to Babel?
 
@@ -86,6 +86,7 @@ Check out our [CONTRIBUTING.md](https://github.com/babel/babel/blob/master/CONTR
 You can also start by checking out the issues with the [help-wanted](https://github.com/babel/babel/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) label.
 
 Our discussions/notes/roadmap: [babel/notes](https://github.com/babel/notes)
+Our progress on TC39 proposals: [babel/proposals](https://github.com/babel/proposals)
 
 ## Packages
 

circle.yml

@@ -1,11 +1,17 @@
+general:
+  artifacts:
+    - "packages/babel-standalone/babel.js"
+    - "packages/babel-standalone/babel.min.js"
+
 machine:
   node:
     version:
-      6
+      8
 
 dependencies:
   pre:
-    - curl -o- -L https://yarnpkg.com/install.sh | bash
+    # Version number can be removed once 0.28.x or higher is released as stable
+    - curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version 0.28.4
   cache_directories:
     - ~/.yarn-cache
   override:
@@ -14,3 +20,9 @@ dependencies:
 test:
   override:
     - make test-ci-coverage
+    # Builds babel-standalone with the regular Babel config
+    - make build
+    # test-ci-coverage doesn't test babel-standalone, as trying to gather coverage
+    # data for a JS file that's several megabytes large is bound to fail. Here,
+    # we just run the babel-standalone test separately.
+    - ./node_modules/mocha/bin/_mocha packages/babel-standalone/test/ --opts test/mocha.opts

eslint_rules/no-undefined-identifier.js

@@ -0,0 +1,46 @@
+"use strict";
+
+function argumentsIsUndefinedString(argumentsArray) {
+  return (
+    argumentsArray.length === 1 &&
+    argumentsArray[0].type === "Literal" &&
+    argumentsArray[0].value === "undefined"
+  );
+}
+
+module.exports = {
+  meta: {
+    schema: [],
+  },
+  create: function(context) {
+    if (context.getFilename().indexOf("packages/babel-plugin-") === -1) {
+      return {};
+    }
+
+    return {
+      CallExpression: function(node) {
+        const callee = node.callee;
+
+        if (
+          callee.type === "MemberExpression" &&
+          argumentsIsUndefinedString(node.arguments)
+        ) {
+          const object = callee.object,
+            property = callee.property;
+
+          if (
+            object.type === "Identifier" &&
+            object.name === "t" &&
+            property.type === "Identifier" &&
+            property.name === "identifier"
+          ) {
+            context.report(
+              node,
+              "Use path.scope.buildUndefinedNode() to create an undefined identifier directly."
+            );
+          }
+        }
+      },
+    };
+  },
+};

lerna.json

@@ -1,6 +1,6 @@
 {
   "lerna": "2.0.0-rc.4",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.20",
   "changelog": {
     "repo": "babel/babel",
     "labels": {
@@ -21,5 +21,10 @@
         "test/**"
       ]
     }
-  }
+  },
+  "packages": [
+    "packages/*"
+  ],
+  "npmClient": "yarn",
+  "useWorkspaces": true
 }

package.json

@@ -11,38 +11,39 @@
   },
   "devDependencies": {
     "async": "^1.5.0",
-    "babel-cli": "7.0.0-alpha.12",
-    "babel-core": "7.0.0-alpha.12",
-    "babel-eslint": "8.0.0-alpha.12",
-    "babel-plugin-istanbul": "^2.0.1",
-    "babel-preset-env": "2.0.0-alpha.12",
-    "babel-preset-flow": "7.0.0-alpha.12",
-    "babel-preset-stage-0": "7.0.0-alpha.12",
-    "babel-register": "7.0.0-alpha.12",
+    "babel-cli": "7.0.0-alpha.18",
+    "babel-core": "7.0.0-alpha.18",
+    "babel-eslint": "8.0.0-alpha.15",
+    "babel-plugin-istanbul": "^4.1.4",
+    "babel-preset-env": "2.0.0-alpha.18",
+    "babel-preset-flow": "7.0.0-alpha.18",
+    "babel-preset-stage-0": "7.0.0-alpha.18",
+    "babel-register": "7.0.0-alpha.18",
+    "babylon": "7.0.0-beta.18",
     "browserify": "^13.1.1",
     "bundle-collapser": "^1.2.1",
-    "chai": "^3.5.0",
-    "chalk": "^1.1.1",
+    "chai": "^4.1.0",
+    "chalk": "^2.0.0",
     "derequire": "^2.0.2",
     "eslint": "^3.14.1",
-    "eslint-config-babel": "^7.0.1",
+    "eslint-config-babel": "^7.0.2",
     "eslint-plugin-flowtype": "^2.20.0",
     "eslint-plugin-prettier": "^2.1.2",
-    "flow-bin": "^0.41.0",
+    "flow-bin": "^0.52.0",
     "gulp": "^3.9.0",
-    "gulp-babel": "babel/gulp-babel#b7-alpha",
+    "gulp-babel": "^7.0.0",
     "gulp-newer": "^1.0.0",
     "gulp-plumber": "^1.0.1",
     "gulp-util": "^3.0.7",
     "gulp-watch": "^4.3.5",
     "husky": "^0.13.2",
-    "lerna": "2.0.0-rc.4",
-    "lerna-changelog": "^0.2.0",
+    "lerna": "2.0.0",
+    "lerna-changelog": "^0.5.0",
     "lint-staged": "^3.6.1",
     "lodash": "^4.2.0",
     "mocha": "^3.0.0",
-    "nyc": "^10.0.0",
-    "output-file-sync": "^1.1.1",
+    "nyc": "^11.0.3",
+    "output-file-sync": "^2.0.0",
     "prettier": "^1.5.0",
     "rimraf": "^2.4.3",
     "semver": "^5.0.0",
@@ -51,21 +52,26 @@
   },
   "engines": {
     "node": ">= 4.x <= 8.x",
-    "npm": ">= 2.x <= 5.x"
+    "npm": ">= 2.x <= 5.x",
+    "yarn": ">=0.27.5 || >=1.0.0-20170811"
   },
   "nyc": {
     "all": true,
     "exclude": [
       "scripts/*.js",
-      "packages/*/test/**"
+      "packages/*/test/**",
+      "packages/babel-standalone/**"
     ],
     "sourceMap": false,
     "instrument": false
   },
   "lint-staged": {
     "*.js": [
-      "eslint --format=codeframe --fix",
+      "eslint --format=codeframe --fix --rulesdir='./eslint_rules'",
       "git add"
     ]
-  }
+  },
+  "workspaces": [
+    "packages/*"
+  ]
 }

packages/.eslintrc

@@ -1,5 +1,6 @@
 {
   "rules": {
-    "prettier/prettier": ["error", { "trailingComma": "all" }]
+    "prettier/prettier": ["error", { "trailingComma": "all" }],
+    "no-undefined-identifier": 2
   }
 }

packages/babel-cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "babel-cli",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.20",
   "description": "Babel command line.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -16,24 +16,24 @@
     "compiler"
   ],
   "dependencies": {
-    "babel-core": "7.0.0-alpha.15",
-    "babel-polyfill": "7.0.0-alpha.15",
-    "babel-register": "7.0.0-alpha.15",
+    "babel-core": "7.0.0-alpha.20",
+    "babel-polyfill": "7.0.0-alpha.20",
+    "babel-register": "7.0.0-alpha.20",
     "commander": "^2.8.1",
     "convert-source-map": "^1.1.0",
     "fs-readdir-recursive": "^1.0.0",
     "glob": "^7.0.0",
     "lodash": "^4.2.0",
-    "output-file-sync": "^1.1.0",
+    "output-file-sync": "^2.0.0",
     "slash": "^1.0.0",
     "source-map": "^0.5.0",
-    "v8flags": "^2.0.10"
+    "v8flags": "^3.0.0"
   },
   "optionalDependencies": {
     "chokidar": "^1.6.1"
   },
   "devDependencies": {
-    "babel-helper-fixtures": "7.0.0-alpha.15"
+    "babel-helper-fixtures": "7.0.0-alpha.20"
   },
   "bin": {
     "babel-doctor": "./bin/babel-doctor.js",

packages/babel-cli/src/babel/index.js

@@ -48,6 +48,7 @@ commander.option(
   "comma-separated list of plugin names",
   collect,
 );
+commander.option("--config-file [path]", "Path a to .babelrc file to use");
 
 // Basic file input configuration.
 commander.option("--source-type [script|module]", "");
@@ -200,6 +201,10 @@ if (errors.length) {
 //
 
 const opts = commander.opts();
+//the configFile CLI option maps to the extends option in the node API
+if (opts.configFile) {
+  opts.extends = opts.configFile;
+}
 
 // Delete options that are specific to babel-cli and shouldn't be passed to babel-core.
 delete opts.version;
@@ -210,6 +215,7 @@ delete opts.outFile;
 delete opts.outDir;
 delete opts.copyFiles;
 delete opts.quiet;
+delete opts.configFile;
 
 // Commander will default the "--no-" arguments to true, but we want to leave them undefined so that
 // babel-core can handle the default-assignment logic on its own.

packages/babel-cli/test/.othername_babelrc

@@ -0,0 +1,3 @@
+{
+  "comments": false
+}

packages/babel-cli/test/fixtures/babel/--config-file babelrc nocomment/options.json

@@ -0,0 +1,3 @@
+{
+  "args": ["--config-file", "../.othername_babelrc"]
+}

packages/babel-cli/test/fixtures/babel/--config-file babelrc nocomment/stdin.txt

@@ -0,0 +1,7 @@
+/*
+ Test comment
+ */
+
+arr.map(x => x * MULTIPLIER);
+
+// END OF FILE

packages/babel-cli/test/fixtures/babel/--config-file babelrc nocomment/stdout.txt

@@ -0,0 +1,5 @@
+"use strict";
+
+arr.map(function (x) {
+  return x * MULTIPLIER;
+});

packages/babel-code-frame/package.json

@@ -1,6 +1,6 @@
 {
   "name": "babel-code-frame",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.20",
   "description": "Generate errors that contain a code frame that point to source locations.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -8,8 +8,11 @@
   "repository": "https://github.com/babel/babel/tree/master/packages/babel-code-frame",
   "main": "lib/index.js",
   "dependencies": {
-    "chalk": "^1.1.0",
+    "chalk": "^2.0.0",
     "esutils": "^2.0.2",
     "js-tokens": "^3.0.0"
+  },
+  "devDependencies": {
+    "strip-ansi": "^4.0.0"
   }
 }

packages/babel-code-frame/test/index.js

@@ -1,5 +1,6 @@
 import assert from "assert";
 import chalk from "chalk";
+import stripAnsi from "strip-ansi";
 import codeFrame, { codeFrameColumns } from "..";
 
 describe("babel-code-frame", function() {
@@ -100,7 +101,7 @@ describe("babel-code-frame", function() {
   it("opts.highlightCode", function() {
     const rawLines = "console.log('babel')";
     const result = codeFrame(rawLines, 1, 9, { highlightCode: true });
-    const stripped = chalk.stripColor(result);
+    const stripped = stripAnsi(result);
     assert.ok(result.length > stripped.length);
     assert.equal(
       stripped,

packages/babel-core/package.json

@@ -1,6 +1,6 @@
 {
   "name": "babel-core",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.20",
   "description": "Babel compiler core.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -25,14 +25,14 @@
     "./lib/config/loading/files/index.js": "./lib/config/loading/files/index-browser.js"
   },
   "dependencies": {
-    "babel-code-frame": "7.0.0-alpha.15",
-    "babel-generator": "7.0.0-alpha.15",
-    "babel-helpers": "7.0.0-alpha.15",
-    "babel-messages": "7.0.0-alpha.15",
-    "babel-template": "7.0.0-alpha.15",
-    "babel-traverse": "7.0.0-alpha.15",
-    "babel-types": "7.0.0-alpha.15",
-    "babylon": "7.0.0-beta.15",
+    "babel-code-frame": "7.0.0-alpha.20",
+    "babel-generator": "7.0.0-alpha.20",
+    "babel-helpers": "7.0.0-alpha.20",
+    "babel-messages": "7.0.0-alpha.20",
+    "babel-template": "7.0.0-alpha.20",
+    "babel-traverse": "7.0.0-alpha.20",
+    "babel-types": "7.0.0-alpha.20",
+    "babylon": "7.0.0-beta.22",
     "convert-source-map": "^1.1.0",
     "debug": "^2.1.1",
     "json5": "^0.5.0",
@@ -42,7 +42,7 @@
     "source-map": "^0.5.0"
   },
   "devDependencies": {
-    "babel-helper-transform-fixture-test-runner": "7.0.0-alpha.15",
-    "babel-register": "7.0.0-alpha.15"
+    "babel-helper-transform-fixture-test-runner": "7.0.0-alpha.20",
+    "babel-register": "7.0.0-alpha.20"
   }
 }

packages/babel-core/src/config/build-config-chain.js

@@ -3,6 +3,9 @@
 import { getEnv } from "./helpers/environment";
 import path from "path";
 import micromatch from "micromatch";
+import buildDebug from "debug";
+
+const debug = buildDebug("babel:config:config-chain");
 
 import { findConfigs, loadConfig } from "./loading/files";
 
@@ -67,7 +70,15 @@ class ConfigChainBuilder {
         );
       }
 
-      if (this.matchesPatterns(ignore, dirname)) return true;
+      if (this.matchesPatterns(ignore, dirname)) {
+        debug(
+          "Ignored %o because it matched one of %O from %o",
+          this.filename,
+          ignore,
+          dirname,
+        );
+        return true;
+      }
     }
 
     if (only) {
@@ -77,7 +88,15 @@ class ConfigChainBuilder {
         );
       }
 
-      if (!this.matchesPatterns(only, dirname)) return true;
+      if (!this.matchesPatterns(only, dirname)) {
+        debug(
+          "Ignored %o because it failed to match one of %O from %o",
+          this.filename,
+          only,
+          dirname,
+        );
+        return true;
+      }
     }
 
     return false;

packages/babel-core/src/config/loading/files/configuration.js

@@ -1,5 +1,6 @@
 // @flow
 
+import buildDebug from "debug";
 import path from "path";
 import fs from "fs";
 import json5 from "json5";
@@ -7,6 +8,8 @@ import resolve from "resolve";
 import { getEnv } from "../../helpers/environment";
 import { makeStrongCache } from "../../caching";
 
+const debug = buildDebug("babel:config:loading:files:configuration");
+
 type ConfigFile = {
   filepath: string,
   dirname: string,
@@ -31,6 +34,7 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
       const ignore = readIgnoreConfig(ignoreLoc);
 
       if (ignore) {
+        debug("Found ignore %o from %o.", ignore.filepath, dirname);
         confs.push(ignore);
         foundIgnore = true;
       }
@@ -57,6 +61,7 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
       }, null);
 
       if (conf) {
+        debug("Found configuration %o from %o.", conf.filepath, dirname);
         confs.push(conf);
         foundConfig = true;
       }
@@ -80,6 +85,7 @@ export function loadConfig(name: string, dirname: string): ConfigFile {
     throw new Error(`Config file ${filepath} contains no configuration data`);
   }
 
+  debug("Loaded config %o from $o.", name, dirname);
   return conf;
 }
 
@@ -93,14 +99,31 @@ function readConfig(filepath) {
     : readConfigFile(filepath);
 }
 
+const LOADING_CONFIGS = new Set();
 const readConfigJS = makeStrongCache((filepath, cache) => {
   if (!fs.existsSync(filepath)) {
     cache.forever();
     return null;
   }
 
+  // The `require()` call below can make this code reentrant if a require hook like babel-register has been
+  // loaded into the system. That would cause Babel to attempt to compile the `.babelrc.js` file as it loads
+  // below. To cover this case, we auto-ignore re-entrant config processing.
+  if (LOADING_CONFIGS.has(filepath)) {
+    cache.never();
+
+    debug("Auto-ignoring usage of config %o.", filepath);
+    return {
+      filepath,
+      dirname: path.dirname(filepath),
+      options: {},
+    };
+  }
+
   let options;
   try {
+    LOADING_CONFIGS.add(filepath);
+
     // $FlowIssue
     const configModule = (require(filepath): mixed);
     options =
@@ -110,6 +133,8 @@ const readConfigJS = makeStrongCache((filepath, cache) => {
   } catch (err) {
     err.message = `${filepath}: Error while loading config - ${err.message}`;
     throw err;
+  } finally {
+    LOADING_CONFIGS.delete(filepath);
   }
 
   if (typeof options === "function") {

packages/babel-core/src/config/loading/files/plugins.js

@@ -4,9 +4,12 @@
  * This file handles all logic for converting string-based configuration references into loaded objects.
  */
 
+import buildDebug from "debug";
 import resolve from "resolve";
 import path from "path";
 
+const debug = buildDebug("babel:config:loading:files:plugins");
+
 const EXACT_RE = /^module:/;
 const BABEL_PLUGIN_PREFIX_RE = /^(?!@|module:|[^/\/]+[/\/]|babel-plugin-)/;
 const BABEL_PRESET_PREFIX_RE = /^(?!@|module:|[^/\/]+[/\/]|babel-preset-)/;
@@ -32,10 +35,10 @@ export function loadPlugin(
     throw new Error(`Plugin ${name} not found relative to ${dirname}`);
   }
 
-  return {
-    filepath,
-    value: requireModule(filepath),
-  };
+  const value = requireModule("plugin", filepath);
+  debug("Loaded plugin %o from %o.", name, dirname);
+
+  return { filepath, value };
 }
 
 export function loadPreset(
@@ -47,10 +50,11 @@ export function loadPreset(
     throw new Error(`Preset ${name} not found relative to ${dirname}`);
   }
 
-  return {
-    filepath,
-    value: requireModule(filepath),
-  };
+  const value = requireModule("preset", filepath);
+
+  debug("Loaded preset %o from %o.", name, dirname);
+
+  return { filepath, value };
 }
 
 export function loadParser(
@@ -59,7 +63,7 @@ export function loadParser(
 ): { filepath: string, value: Function } {
   const filepath = resolve.sync(name, { basedir: dirname });
 
-  const mod = requireModule(filepath);
+  const mod = requireModule("parser", filepath);
 
   if (!mod) {
     throw new Error(
@@ -71,10 +75,13 @@ export function loadParser(
       `Parser ${name} relative to ${dirname} does not export a .parse function`,
     );
   }
+  const value = mod.parse;
+
+  debug("Loaded parser %o from %o.", name, dirname);
 
   return {
     filepath,
-    value: mod.parse,
+    value,
   };
 }
 
@@ -84,7 +91,7 @@ export function loadGenerator(
 ): { filepath: string, value: Function } {
   const filepath = resolve.sync(name, { basedir: dirname });
 
-  const mod = requireModule(filepath);
+  const mod = requireModule("generator", filepath);
 
   if (!mod) {
     throw new Error(
@@ -96,10 +103,13 @@ export function loadGenerator(
       `Generator ${name} relative to ${dirname} does not export a .print function`,
     );
   }
+  const value = mod.print;
+
+  debug("Loaded generator %o from %o.", name, dirname);
 
   return {
     filepath,
-    value: mod.print,
+    value,
   };
 }
 
@@ -185,7 +195,20 @@ function resolveStandardizedName(
   }
 }
 
-function requireModule(name: string): mixed {
-  // $FlowIssue
-  return require(name);
+const LOADING_MODULES = new Set();
+function requireModule(type: string, name: string): mixed {
+  if (LOADING_MODULES.has(name)) {
+    throw new Error(
+      // eslint-disable-next-line max-len
+      `Reentrant ${type} detected trying to load "${name}". This module is not ignored and is trying to load itself while compiling itself, leading to a dependency cycle. We recommend adding it to your "ignore" list in your babelrc, or to a .babelignore.`,
+    );
+  }
+
+  try {
+    LOADING_MODULES.add(name);
+    // $FlowIssue
+    return require(name);
+  } finally {
+    LOADING_MODULES.delete(name);
+  }
 }

packages/babel-core/src/config/option-manager.js

@@ -1,5 +1,3 @@
-// @flow
-
 import * as context from "../index";
 import Plugin from "./plugin";
 import * as messages from "babel-messages";

packages/babel-core/src/transformation/file/index.js

@@ -180,9 +180,24 @@ export default class File extends Store {
 
   addImport(
     source: string,
-    imported: string,
+    imported?: string = "",
     name?: string = imported,
-  ): Object {
+  ): Object | null {
+    const prependDeclaration = (
+      specifiers: Array<BabelNodeImportSpecifier>,
+    ): void => {
+      const declar = t.importDeclaration(specifiers, t.stringLiteral(source));
+      declar._blockHoist = 3;
+
+      this.path.unshiftContainer("body", declar);
+    };
+
+    // import "module-name";
+    if (!imported) {
+      prependDeclaration([]);
+      return null;
+    }
+
     const alias = `${source}:${imported}`;
     let id = this.dynamicImportIds[alias];
 
@@ -202,10 +217,7 @@ export default class File extends Store {
         specifiers.push(t.importSpecifier(id, t.identifier(imported)));
       }
 
-      const declar = t.importDeclaration(specifiers, t.stringLiteral(source));
-      declar._blockHoist = 3;
-
-      this.path.unshiftContainer("body", declar);
+      prependDeclaration(specifiers);
     }
 
     return id;
@@ -236,7 +248,6 @@ export default class File extends Store {
 
     if (t.isFunctionExpression(ref) && !ref.id) {
       ref.body._compact = true;
-      ref._generated = true;
       ref.id = uid;
       ref.type = "FunctionDeclaration";
       this.path.unshiftContainer("body", ref);

packages/babel-core/test/fixtures/plugins/file-add-import/exec.js

@@ -0,0 +1,30 @@
+var res = transform("", {
+  plugins: [
+    function (b) {
+      return {
+        visitor: {
+          Program: function(path, state) {
+            var file = state.file;
+            file.addImport("import-star", "*", "lib");
+            file.addImport("import-default", "default", "foo");
+            file.addImport("import-alias", "bar", "baz");
+            file.addImport("import-default-alias", "quux");
+            file.addImport("import-empty", "");
+            file.addImport("import-none");
+          }
+        }
+      };
+    }
+  ]
+});
+
+var expected = multiline([
+  'import "import-none";',
+  'import "import-empty";',
+  'import { quux as _quux } from "import-default-alias";',
+  'import { bar as _baz } from "import-alias";',
+  'import _foo from "import-default";',
+  'import * as _lib from "import-star";',
+]);
+
+assert.equal(res.code, expected);

packages/babel-core/test/fixtures/transformation/misc/enforce-newline-modules-blacklist/expected.js

@@ -1,2 +1,2 @@
 export function foo() {}
-export function bar() {}
+export function bar() {}

packages/babel-core/test/fixtures/transformation/misc/regression-1155/expected.js

@@ -13,4 +13,4 @@ var Foo = function (_Bar) {
   }
 
   return Foo;
-}(Bar);
+}(Bar);

packages/babel-core/test/fixtures/transformation/misc/regression-1168/expected.js

@@ -1,4 +1,4 @@
 function test() {
   var x = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : "hi";
   return x;
-}
+}

packages/babel-core/test/fixtures/transformation/misc/regression-2765/expected.js

@@ -29,4 +29,4 @@ class Class {
     })();
   }
 
-}
+}

packages/babel-core/test/fixtures/transformation/misc/regression-2892/expected.js

@@ -7,9 +7,13 @@ Object.defineProperty(exports, "__esModule", {
 var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
 var foo = function () {
-  var _ref2 = _asyncToGenerator(regeneratorRuntime.mark(function _callee3() {
+  var _ref2 = _asyncToGenerator(
+  /*#__PURE__*/
+  regeneratorRuntime.mark(function _callee3() {
     var bar = function () {
-      var _ref3 = _asyncToGenerator(regeneratorRuntime.mark(function _callee2() {
+      var _ref3 = _asyncToGenerator(
+      /*#__PURE__*/
+      regeneratorRuntime.mark(function _callee2() {
         var baz;
         return regeneratorRuntime.wrap(function _callee2$(_context2) {
           while (1) {
@@ -58,7 +62,9 @@ var Foo = function () {
   _createClass(Foo, [{
     key: "bar",
     value: function () {
-      var _ref = _asyncToGenerator(regeneratorRuntime.mark(function _callee() {
+      var _ref = _asyncToGenerator(
+      /*#__PURE__*/
+      regeneratorRuntime.mark(function _callee() {
         var baz;
         return regeneratorRuntime.wrap(function _callee$(_context) {
           while (1) {

packages/babel-core/test/fixtures/transformation/misc/regression-4855/expected.js

@@ -1,6 +1,8 @@
 "use strict";
 
 var _values = values;
-value = _values[fieldName];
-rest = babelHelpers.objectWithoutProperties(_values, [fieldName]);
-var error = void 0;
+var _fieldName = fieldName;
+value = _values[_fieldName];
+rest = babelHelpers.objectWithoutProperties(_values, [_fieldName].map(babelHelpers.toPropertyKey));
+_values;
+var error = void 0;

packages/babel-core/test/fixtures/transformation/misc/shebang/expected.js

@@ -1,2 +1,2 @@
 #!/usr/bin/env node
-foobar();
+foobar();

packages/babel-generator/package.json

@@ -1,6 +1,6 @@
 {
   "name": "babel-generator",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.20",
   "description": "Turns an AST into code.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -11,15 +11,15 @@
     "lib"
   ],
   "dependencies": {
-    "babel-messages": "7.0.0-alpha.15",
-    "babel-types": "7.0.0-alpha.15",
-    "jsesc": "^1.3.0",
+    "babel-messages": "7.0.0-alpha.20",
+    "babel-types": "7.0.0-alpha.20",
+    "jsesc": "^2.5.1",
     "lodash": "^4.2.0",
     "source-map": "^0.5.0",
     "trim-right": "^1.0.1"
   },
   "devDependencies": {
-    "babel-helper-fixtures": "7.0.0-alpha.15",
-    "babylon": "^7.0.0-beta.15"
+    "babel-helper-fixtures": "7.0.0-alpha.20",
+    "babylon": "^7.0.0-beta.22"
   }
 }

packages/babel-generator/src/generators/classes.js

@@ -8,6 +8,18 @@ export function ClassDeclaration(node: Object, parent: Object) {
     this.printJoin(node.decorators, node);
   }
 
+  if (node.declare) {
+    // TS
+    this.word("declare");
+    this.space();
+  }
+
+  if (node.abstract) {
+    // TS
+    this.word("abstract");
+    this.space();
+  }
+
   this.word("class");
 
   if (node.id) {
@@ -59,10 +71,25 @@ export function ClassBody(node: Object) {
 export function ClassProperty(node: Object) {
   this.printJoin(node.decorators, node);
 
+  if (node.accessibility) {
+    // TS
+    this.word(node.accessibility);
+    this.space();
+  }
   if (node.static) {
     this.word("static");
     this.space();
   }
+  if (node.abstract) {
+    // TS
+    this.word("abstract");
+    this.space();
+  }
+  if (node.readonly) {
+    // TS
+    this.word("readonly");
+    this.space();
+  }
   if (node.computed) {
     this.token("[");
     this.print(node.key, node);
@@ -71,6 +98,12 @@ export function ClassProperty(node: Object) {
     this._variance(node);
     this.print(node.key, node);
   }
+
+  if (node.optional) {
+    // TS
+    this.token("?");
+  }
+
   this.print(node.typeAnnotation, node);
   if (node.value) {
     this.space();
@@ -82,12 +115,30 @@ export function ClassProperty(node: Object) {
 }
 
 export function ClassMethod(node: Object) {
+  this._classMethodHead(node);
+  this.space();
+  this.print(node.body, node);
+}
+
+export function _classMethodHead(node) {
   this.printJoin(node.decorators, node);
 
+  if (node.accessibility) {
+    // TS
+    this.word(node.accessibility);
+    this.space();
+  }
+
+  if (node.abstract) {
+    // TS
+    this.word("abstract");
+    this.space();
+  }
+
   if (node.static) {
     this.word("static");
     this.space();
   }
 
-  this._method(node);
+  this._methodHead(node);
 }

packages/babel-generator/src/generators/expressions.js

@@ -65,6 +65,8 @@ export function NewExpression(node: Object, parent: Object) {
     return;
   }
 
+  this.print(node.typeParameters, node); // TS
+
   if (node.optional) {
     this.token("?.");
   }
@@ -91,37 +93,16 @@ export function Decorator(node: Object) {
   this.newline();
 }
 
-function commaSeparatorNewline() {
-  this.token(",");
-  this.newline();
-
-  if (!this.endsWith("\n")) this.space();
-}
-
 export function CallExpression(node: Object) {
   this.print(node.callee, node);
 
+  this.print(node.typeParameters, node); // TS
+
   if (node.optional) {
     this.token("?.");
   }
   this.token("(");
-
-  const isPrettyCall = node._prettyCall;
-
-  let separator;
-  if (isPrettyCall) {
-    separator = commaSeparatorNewline;
-    this.newline();
-    this.indent();
-  }
-
-  this.printList(node.arguments, node, { separator });
-
-  if (isPrettyCall) {
-    this.newline();
-    this.dedent();
-  }
-
+  this.printList(node.arguments, node);
   this.token(")");
 }
 

packages/babel-generator/src/generators/flow.js

@@ -1,4 +1,5 @@
 import * as t from "babel-types";
+import { ExportAllDeclaration } from "./modules";
 
 export function AnyTypeAnnotation() {
   this.word("any");
@@ -41,9 +42,28 @@ export function DeclareFunction(node: Object, parent: Object) {
   this.space();
   this.print(node.id, node);
   this.print(node.id.typeAnnotation.typeAnnotation, node);
+
+  if (node.predicate) {
+    this.space();
+    this.print(node.predicate, node);
+  }
+
   this.semicolon();
 }
 
+export function InferredPredicate(/*node: Object*/) {
+  this.token("%");
+  this.word("checks");
+}
+
+export function DeclaredPredicate(node: Object) {
+  this.token("%");
+  this.word("checks");
+  this.token("(");
+  this.print(node.value, node);
+  this.token(")");
+}
+
 export function DeclareInterface(node: Object) {
   this.word("declare");
   this.space();
@@ -75,6 +95,14 @@ export function DeclareTypeAlias(node: Object) {
   this.TypeAlias(node);
 }
 
+export function DeclareOpaqueType(node: Object, parent: Object) {
+  if (!t.isDeclareExportDeclaration(parent)) {
+    this.word("declare");
+    this.space();
+  }
+  this.OpaqueType(node);
+}
+
 export function DeclareVariable(node: Object, parent: Object) {
   if (!t.isDeclareExportDeclaration(parent)) {
     this.word("declare");
@@ -100,17 +128,10 @@ export function DeclareExportDeclaration(node: Object) {
   FlowExportDeclaration.apply(this, arguments);
 }
 
-export function DeclareExportAllDeclaration(node: Object) {
+export function DeclareExportAllDeclaration(/*node: Object*/) {
   this.word("declare");
   this.space();
-  this.word("export");
-  this.space();
-  this.token("*");
-  this.space();
-  this.word("from");
-  this.space();
-  this.print(node.source, node);
-  this.semicolon();
+  ExportAllDeclaration.apply(this, arguments);
 }
 
 function FlowExportDeclaration(node: Object) {
@@ -290,38 +311,27 @@ export function TypeAlias(node: Object) {
   this.semicolon();
 }
 
-export function TypeAnnotation(node: Object) {
-  this.token(":");
+export function OpaqueType(node: Object) {
+  this.word("opaque");
   this.space();
-  if (node.optional) this.token("?");
-  this.print(node.typeAnnotation, node);
-}
-
-export function TypeParameter(node: Object) {
-  this._variance(node);
-
-  this.word(node.name);
-
-  if (node.bound) {
-    this.print(node.bound, node);
+  this.word("type");
+  this.space();
+  this.print(node.id, node);
+  this.print(node.typeParameters, node);
+  if (node.supertype) {
+    this.token(":");
+    this.space();
+    this.print(node.supertype, node);
   }
-
-  if (node.default) {
+  if (node.impltype) {
     this.space();
     this.token("=");
     this.space();
-    this.print(node.default, node);
+    this.print(node.impltype, node);
   }
+  this.semicolon();
 }
 
-export function TypeParameterInstantiation(node: Object) {
-  this.token("<");
-  this.printList(node.params, node, {});
-  this.token(">");
-}
-
-export { TypeParameterInstantiation as TypeParameterDeclaration };
-
 export function ObjectTypeAnnotation(node: Object) {
   if (node.exact) {
     this.token("{|");

packages/babel-generator/src/generators/index.js

@@ -8,3 +8,5 @@ export * from "./types";
 export * from "./flow";
 export * from "./base";
 export * from "./jsx";
+export * from "./tsFlowCommon";
+export * from "./typescript";

packages/babel-generator/src/generators/methods.js

@@ -3,20 +3,31 @@ import * as t from "babel-types";
 export function _params(node: Object) {
   this.print(node.typeParameters, node);
   this.token("(");
-  this.printList(node.params, node, {
-    iterator: node => {
-      if (node.optional) this.token("?");
-      this.print(node.typeAnnotation, node);
-    },
-  });
+  this._parameters(node.params, node);
   this.token(")");
 
-  if (node.returnType) {
-    this.print(node.returnType, node);
+  this.print(node.returnType, node);
+}
+
+export function _parameters(parameters, parent) {
+  for (let i = 0; i < parameters.length; i++) {
+    this._param(parameters[i], parent);
+
+    if (i < parameters.length - 1) {
+      this.token(",");
+      this.space();
+    }
   }
 }
 
-export function _method(node: Object) {
+export function _param(parameter, parent) {
+  this.printJoin(parameter.decorators, parameter);
+  this.print(parameter, parent);
+  if (parameter.optional) this.token("?"); // TS / flow
+  this.print(parameter.typeAnnotation, parameter); // TS / flow
+}
+
+export function _methodHead(node: Object) {
   const kind = node.kind;
   const key = node.key;
 
@@ -44,12 +55,25 @@ export function _method(node: Object) {
     this.print(key, node);
   }
 
+  if (node.optional) {
+    // TS
+    this.token("?");
+  }
+
   this._params(node);
-  this.space();
-  this.print(node.body, node);
 }
 
-export function FunctionExpression(node: Object) {
+export function _predicate(node: Object) {
+  if (node.predicate) {
+    if (!node.returnType) {
+      this.token(":");
+    }
+    this.space();
+    this.print(node.predicate, node);
+  }
+}
+
+export function _functionHead(node: Object) {
   if (node.async) {
     this.word("async");
     this.space();
@@ -57,14 +81,17 @@ export function FunctionExpression(node: Object) {
   this.word("function");
   if (node.generator) this.token("*");
 
+  this.space();
   if (node.id) {
-    this.space();
     this.print(node.id, node);
-  } else {
-    this.space();
   }
 
   this._params(node);
+  this._predicate(node);
+}
+
+export function FunctionExpression(node: Object) {
+  this._functionHead(node);
   this.space();
   this.print(node.body, node);
 }
@@ -89,6 +116,8 @@ export function ArrowFunctionExpression(node: Object) {
     this._params(node);
   }
 
+  this._predicate(node);
+
   this.space();
   this.token("=>");
   this.space();

packages/babel-generator/src/generators/modules.js

@@ -44,6 +44,10 @@ export function ExportNamespaceSpecifier(node: Object) {
 export function ExportAllDeclaration(node: Object) {
   this.word("export");
   this.space();
+  if (node.exportKind === "type") {
+    this.word("type");
+    this.space();
+  }
   this.token("*");
   this.space();
   this.word("from");

packages/babel-generator/src/generators/statements.js

@@ -123,8 +123,8 @@ function buildLabelStatement(prefix, key = "label") {
     const label = node[key];
     if (label) {
       this.space();
-
-      const terminatorState = this.startTerminatorless();
+      const isLabel = key == "label";
+      const terminatorState = this.startTerminatorless(isLabel);
       this.print(label, node);
       this.endTerminatorless(terminatorState);
     }
@@ -171,10 +171,12 @@ export function TryStatement(node: Object) {
 export function CatchClause(node: Object) {
   this.word("catch");
   this.space();
-  this.token("(");
-  this.print(node.param, node);
-  this.token(")");
-  this.space();
+  if (node.param) {
+    this.token("(");
+    this.print(node.param, node);
+    this.token(")");
+    this.space();
+  }
   this.print(node.body, node);
 }
 
@@ -234,6 +236,12 @@ function constDeclarationIndent() {
 }
 
 export function VariableDeclaration(node: Object, parent: Object) {
+  if (node.declare) {
+    // TS
+    this.word("declare");
+    this.space();
+  }
+
   this.word(node.kind);
   this.space();
 

packages/babel-generator/src/generators/tsFlowCommon.js

@@ -0,0 +1,38 @@
+export function TypeAnnotation(node) {
+  this.token(":");
+  this.space();
+  if (node.optional) this.token("?");
+  this.print(node.typeAnnotation, node);
+}
+
+export function TypeParameterInstantiation(node): void {
+  this.token("<");
+  this.printList(node.params, node, {});
+  this.token(">");
+}
+
+export { TypeParameterInstantiation as TypeParameterDeclaration };
+
+export function TypeParameter(node) {
+  this._variance(node);
+
+  this.word(node.name);
+
+  if (node.bound) {
+    this.print(node.bound, node);
+  }
+
+  if (node.constraint) {
+    this.space();
+    this.word("extends");
+    this.space();
+    this.print(node.constraint, node);
+  }
+
+  if (node.default) {
+    this.space();
+    this.token("=");
+    this.space();
+    this.print(node.default, node);
+  }
+}

packages/babel-generator/src/generators/types.js

@@ -31,7 +31,9 @@ export { ObjectExpression as ObjectPattern };
 
 export function ObjectMethod(node: Object) {
   this.printJoin(node.decorators, node);
-  this._method(node);
+  this._methodHead(node);
+  this.space();
+  this.print(node.body, node);
 }
 
 export function ObjectProperty(node: Object) {

packages/babel-generator/src/generators/typescript.js

@@ -0,0 +1,456 @@
+export function TSParameterProperty(node) {
+  if (node.accessibility) {
+    this.word(node.accessibility);
+    this.space();
+  }
+
+  if (node.readonly) {
+    this.word("readonly");
+    this.space();
+  }
+
+  this._param(node.parameter);
+}
+
+export function TSDeclareFunction(node) {
+  if (node.declare) {
+    this.word("declare");
+    this.space();
+  }
+  this._functionHead(node);
+  this.token(";");
+}
+
+export function TSDeclareMethod(node) {
+  this._classMethodHead(node);
+  this.token(";");
+}
+
+export function TSQualifiedName(node) {
+  this.print(node.left, node);
+  this.token(".");
+  this.print(node.right, node);
+}
+
+export function TSCallSignatureDeclaration(node) {
+  this.tsPrintSignatureDeclarationBase(node);
+}
+
+export function TSConstructSignatureDeclaration(node) {
+  this.word("new");
+  this.space();
+  this.tsPrintSignatureDeclarationBase(node);
+}
+
+export function TSPropertySignature(node) {
+  const { readonly, initializer } = node;
+  if (readonly) {
+    this.word("readonly");
+    this.space();
+  }
+  this.tsPrintPropertyOrMethodName(node);
+  this.print(node.typeAnnotation, node);
+  if (initializer) {
+    this.space();
+    this.token("=");
+    this.space();
+    this.print(initializer, node);
+  }
+  this.token(";");
+}
+
+export function tsPrintPropertyOrMethodName(node) {
+  if (node.computed) {
+    this.token("[");
+  }
+  this.print(node.key, node);
+  if (node.computed) {
+    this.token("]");
+  }
+  if (node.optional) {
+    this.token("?");
+  }
+}
+
+export function TSMethodSignature(node) {
+  this.tsPrintPropertyOrMethodName(node);
+  this.tsPrintSignatureDeclarationBase(node);
+  this.token(";");
+}
+
+export function TSIndexSignature(node) {
+  const { readonly } = node;
+  if (readonly) {
+    this.word("readonly");
+    this.space();
+  }
+  this.token("[");
+  this._parameters(node.parameters, node);
+  this.token("]");
+  this.print(node.typeAnnotation, node);
+  this.token(";");
+}
+
+export function TSAnyKeyword() {
+  this.word("any");
+}
+export function TSNumberKeyword() {
+  this.word("number");
+}
+export function TSObjectKeyword() {
+  this.word("object");
+}
+export function TSBooleanKeyword() {
+  this.word("boolean");
+}
+export function TSStringKeyword() {
+  this.word("string");
+}
+export function TSSymbolKeyword() {
+  this.word("symbol");
+}
+export function TSVoidKeyword() {
+  this.word("void");
+}
+export function TSUndefinedKeyword() {
+  this.word("undefined");
+}
+export function TSNullKeyword() {
+  this.word("null");
+}
+export function TSNeverKeyword() {
+  this.word("never");
+}
+
+export function TSThisType() {
+  this.word("this");
+}
+
+export function TSFunctionType(node) {
+  this.tsPrintFunctionOrConstructorType(node);
+}
+
+export function TSConstructorType(node) {
+  this.word("new");
+  this.space();
+  this.tsPrintFunctionOrConstructorType(node);
+}
+
+export function tsPrintFunctionOrConstructorType(
+  node: FunctionOrConstructorType,
+) {
+  const { typeParameters, parameters } = node;
+  this.print(typeParameters, node);
+  this.token("(");
+  this._parameters(parameters, node);
+  this.token(")");
+  this.space();
+  this.token("=>");
+  this.space();
+  this.print(node.typeAnnotation.typeAnnotation, node);
+}
+
+export function TSTypeReference(node) {
+  this.print(node.typeName, node);
+  this.print(node.typeParameters, node);
+}
+
+export function TSTypePredicate(node) {
+  this.print(node.parameterName);
+  this.space();
+  this.word("is");
+  this.space();
+  this.print(node.typeAnnotation.typeAnnotation);
+}
+
+export function TSTypeQuery(node) {
+  this.word("typeof");
+  this.space();
+  this.print(node.exprName);
+}
+
+export function TSTypeLiteral(node) {
+  this.tsPrintTypeLiteralOrInterfaceBody(node.members, node);
+}
+
+export function tsPrintTypeLiteralOrInterfaceBody(members, node) {
+  this.tsPrintBraced(members, node);
+}
+
+export function tsPrintBraced(members, node) {
+  this.token("{");
+  if (members.length) {
+    this.indent();
+    this.newline();
+    for (const member of members) {
+      this.print(member, node);
+      //this.token(sep);
+      this.newline();
+    }
+    this.dedent();
+    this.rightBrace();
+  } else {
+    this.token("}");
+  }
+}
+
+export function TSArrayType(node) {
+  this.print(node.elementType);
+  this.token("[]");
+}
+
+export function TSTupleType(node) {
+  this.token("[");
+  this.printList(node.elementTypes, node);
+  this.token("]");
+}
+
+export function TSUnionType(node) {
+  this.tsPrintUnionOrIntersectionType(node, "|");
+}
+
+export function TSIntersectionType(node) {
+  this.tsPrintUnionOrIntersectionType(node, "&");
+}
+
+export function tsPrintUnionOrIntersectionType(node, sep) {
+  this.printJoin(node.types, node, {
+    separator() {
+      this.space();
+      this.token(sep);
+      this.space();
+    },
+  });
+}
+
+export function TSParenthesizedType(node) {
+  this.token("(");
+  this.print(node.typeAnnotation, node);
+  this.token(")");
+}
+
+export function TSTypeOperator(node) {
+  this.token(node.operator);
+  this.space();
+  this.print(node.typeAnnotation, node);
+}
+
+export function TSIndexedAccessType(node) {
+  this.print(node.objectType, node);
+  this.token("[");
+  this.print(node.indexType, node);
+  this.token("]");
+}
+
+export function TSMappedType(node) {
+  const { readonly, typeParameter, optional } = node;
+  this.token("{");
+  this.space();
+  if (readonly) {
+    this.word("readonly");
+    this.space();
+  }
+
+  this.token("[");
+  this.word(typeParameter.name);
+  this.space();
+  this.word("in");
+  this.space();
+  this.print(typeParameter.constraint, typeParameter);
+  this.token("]");
+
+  if (optional) {
+    this.token("?");
+  }
+  this.token(":");
+  this.space();
+  this.print(node.typeAnnotation, node);
+  this.space();
+  this.token("}");
+}
+
+export function TSLiteralType(node) {
+  this.print(node.literal, node);
+}
+
+export function TSExpressionWithTypeArguments(node) {
+  this.print(node.expression, node);
+  this.print(node.typeParameters, node);
+}
+
+export function TSInterfaceDeclaration(node) {
+  const { declare, id, typeParameters, extends: extendz, body } = node;
+  if (declare) {
+    this.word("declare");
+    this.space();
+  }
+  this.word("interface");
+  this.space();
+  this.print(id, node);
+  this.print(typeParameters, node);
+  if (extendz) {
+    this.space();
+    this.word("extends");
+    this.space();
+    this.printList(extendz, node);
+  }
+  this.space();
+  this.print(body, node);
+}
+
+export function TSInterfaceBody(node) {
+  this.tsPrintTypeLiteralOrInterfaceBody(node.body, node);
+}
+
+export function TSTypeAliasDeclaration(node) {
+  const { declare, id, typeParameters, typeAnnotation } = node;
+  if (declare) {
+    this.word("declare");
+    this.space();
+  }
+  this.word("type");
+  this.space();
+  this.print(id, node);
+  this.print(typeParameters, node);
+  this.space();
+  this.token("=");
+  this.space();
+  this.print(typeAnnotation, node);
+  this.token(";");
+}
+
+export function TSAsExpression(node) {
+  const { expression, typeAnnotation } = node;
+  this.print(expression, node);
+  this.space();
+  this.word("as");
+  this.space();
+  this.print(typeAnnotation, node);
+}
+
+export function TSTypeAssertion(node) {
+  const { typeAnnotation, expression } = node;
+  this.token("<");
+  this.print(typeAnnotation, node);
+  this.token(">");
+  this.space();
+  this.print(expression, node);
+}
+
+export function TSEnumDeclaration(node) {
+  const { declare, const: isConst, id, members } = node;
+  if (declare) {
+    this.word("declare");
+    this.space();
+  }
+  if (isConst) {
+    this.word("const");
+    this.space();
+  }
+  this.word("enum");
+  this.space();
+  this.print(id, node);
+  this.space();
+  this.tsPrintBraced(members, node);
+}
+
+export function TSEnumMember(node) {
+  const { id, initializer } = node;
+  this.print(id, node);
+  if (initializer) {
+    this.space();
+    this.token("=");
+    this.space();
+    this.print(initializer, node);
+  }
+  this.token(",");
+}
+
+export function TSModuleDeclaration(node) {
+  const { declare, id } = node;
+
+  if (declare) {
+    this.word("declare");
+    this.space();
+  }
+
+  if (!node.global) {
+    this.word(id.type === "Identifier" ? "namespace" : "module");
+    this.space();
+  }
+  this.print(id, node);
+
+  if (!node.body) {
+    this.token(";");
+    return;
+  }
+
+  let body = node.body;
+  while (body.type === "TSModuleDeclaration") {
+    this.token(".");
+    this.print(body.id, body);
+    body = body.body;
+  }
+
+  this.space();
+  this.print(body, node);
+}
+
+export function TSModuleBlock(node) {
+  this.tsPrintBraced(node.body, node);
+}
+
+export function TSImportEqualsDeclaration(node) {
+  const { isExport, id, moduleReference } = node;
+  if (isExport) {
+    this.word("export");
+    this.space();
+  }
+  this.word("import");
+  this.space();
+  this.print(id, node);
+  this.space();
+  this.token("=");
+  this.space();
+  this.print(moduleReference, node);
+  this.token(";");
+}
+
+export function TSExternalModuleReference(node) {
+  this.token("require(");
+  this.print(node.expression, node);
+  this.token(")");
+}
+
+export function TSNonNullExpression(node) {
+  this.print(node.expression, node);
+  this.token("!");
+}
+
+export function TSExportAssignment(node) {
+  this.word("export");
+  this.space();
+  this.token("=");
+  this.space();
+  this.print(node.expression, node);
+  this.token(";");
+}
+
+export function TSNamespaceExportDeclaration(node) {
+  this.word("export");
+  this.space();
+  this.word("as");
+  this.space();
+  this.word("namespace");
+  this.space();
+  this.print(node.id, node);
+}
+
+export function tsPrintSignatureDeclarationBase(node) {
+  const { typeParameters, parameters } = node;
+  this.print(typeParameters, node);
+  this.token("(");
+  this._parameters(parameters, node);
+  this.token(")");
+  this.print(node.typeAnnotation, node);
+}

packages/babel-generator/src/node/parentheses.js

@@ -93,6 +93,14 @@ export function Binary(node: Object, parent: Object): boolean {
   return false;
 }
 
+export function TSAsExpression() {
+  return true;
+}
+
+export function TSTypeAssertion() {
+  return true;
+}
+
 export function BinaryExpression(node: Object, parent: Object): boolean {
   // let i = (1 in []);
   // for ((1 in []);;);
@@ -173,7 +181,9 @@ export function ConditionalExpression(node: Object, parent: Object): boolean {
     t.isBinary(parent) ||
     t.isConditionalExpression(parent, { test: node }) ||
     t.isAwaitExpression(parent) ||
-    t.isTaggedTemplateExpression(parent)
+    t.isTaggedTemplateExpression(parent) ||
+    t.isTSTypeAssertion(parent) ||
+    t.isTSAsExpression(parent)
   ) {
     return true;
   }

packages/babel-generator/src/printer.js

@@ -43,6 +43,7 @@ export default class Printer {
   _insideAux: boolean = false;
   _printedCommentStarts: Object = {};
   _parenPushNewlineState: ?Object = null;
+  _noLineTerminator: boolean = false;
   _printAuxAfterOnNextUserNode: boolean = false;
   _printedComments: WeakSet = new WeakSet();
   _endsWithInteger = false;
@@ -281,7 +282,7 @@ export default class Printer {
    *
    * This is to prevent breaking semantics for terminatorless separator nodes. eg:
    *
-   *    return foo;
+   *   return foo;
    *
    * returns `foo`. But if we do:
    *
@@ -291,10 +292,15 @@ export default class Printer {
    *  `undefined` will be returned and not `foo` due to the terminator.
    */
 
-  startTerminatorless(): Object {
-    return (this._parenPushNewlineState = {
-      printed: false,
-    });
+  startTerminatorless(isLabel: boolean = false): Object {
+    if (isLabel) {
+      this._noLineTerminator = true;
+      return null;
+    } else {
+      return (this._parenPushNewlineState = {
+        printed: false,
+      });
+    }
   }
 
   /**
@@ -302,7 +308,8 @@ export default class Printer {
    */
 
   endTerminatorless(state: Object) {
-    if (state.printed) {
+    this._noLineTerminator = false;
+    if (state && state.printed) {
       this.dedent();
       this.newline();
       this.token(")");
@@ -319,7 +326,6 @@ export default class Printer {
 
     const printMethod = this[node.type];
     if (!printMethod) {
-      // eslint-disable-next-line max-len
       throw new ReferenceError(
         `unknown node of type ${JSON.stringify(
           node.type,
@@ -531,13 +537,19 @@ export default class Printer {
     const isBlockComment = comment.type === "CommentBlock";
 
     // Always add a newline before a block comment
-    this.newline(this._buf.hasContent() && isBlockComment ? 1 : 0);
+    this.newline(
+      this._buf.hasContent() && !this._noLineTerminator && isBlockComment
+        ? 1
+        : 0,
+    );
 
     if (!this.endsWith("[") && !this.endsWith("{")) this.space();
 
-    let val = !isBlockComment ? `//${comment.value}\n` : `/*${comment.value}*/`;
+    let val =
+      !isBlockComment && !this._noLineTerminator
+        ? `//${comment.value}\n`
+        : `/*${comment.value}*/`;
 
-    //
     if (isBlockComment && this.format.indent.adjustMultilineComment) {
       const offset = comment.loc && comment.loc.start.column;
       if (offset) {
@@ -560,7 +572,7 @@ export default class Printer {
     });
 
     // Always add a newline after a block comment
-    this.newline(isBlockComment ? 1 : 0);
+    this.newline(isBlockComment && !this._noLineTerminator ? 1 : 0);
   }
 
   _printComments(comments?: Array<Object>) {

packages/babel-generator/test/fixtures/auto-string/double/expected.js

@@ -2,4 +2,4 @@ foo("foo");
 foo("foo\nlol");
 foo("foo\n\"lol");
 foo("foo\n\"'lol");
-foo("😂");
+foo("😂");

packages/babel-generator/test/fixtures/auto-string/jsx/options.json

@@ -0,0 +1 @@
+{ "plugins": ["jsx"] }

packages/babel-generator/test/fixtures/auto-string/single/expected.js

@@ -2,4 +2,4 @@ foo('foo');
 foo('foo\nlol');
 foo('foo\n"lol');
 foo('foo\n"\'lol');
-foo('😂');
+foo('😂');

packages/babel-generator/test/fixtures/comments/2-space-multi-comment/expected.js

@@ -3,4 +3,4 @@ function test() {
    * this is comment
    */
   var i = 20;
-}
+}

packages/babel-generator/test/fixtures/comments/block-line-comment-with-concise-format/expected.js

@@ -1,2 +1,2 @@
 { print("hello"); // comment
-}
+}

packages/babel-generator/test/fixtures/comments/block-line-comment-with-retainlines-option/expected.js

@@ -1,4 +1,4 @@
 {
   print("hello");
   // comment
-}
+}

packages/babel-generator/test/fixtures/comments/block-line-comment/expected.js

@@ -1,4 +1,4 @@
 // Leading to block
 {
   print("hello");
-}
+}

packages/babel-generator/test/fixtures/comments/comment-statement-with-retainlines-option/expected.js

@@ -2,4 +2,4 @@
 print("hello");
 
 // comment2
-print("hello2");
+print("hello2");

packages/babel-generator/test/fixtures/comments/do-while-line-comment/expected.js

@@ -1,2 +1,2 @@
 do {} // LINE
-while (true);
+while (true);

packages/babel-generator/test/fixtures/comments/empty-line-comment/expected.js

@@ -1,4 +1,4 @@
 function test() {
   // Leading to EmptyStatement
   ; // Trailing to EmptyStatement
-}
+}

packages/babel-generator/test/fixtures/comments/empty/expected.js

@@ -1 +0,0 @@
-

packages/babel-generator/test/fixtures/comments/return-no-argument/expected.js

@@ -1,3 +1,3 @@
 (function () {
   return; // comment
-})();
+})();

packages/babel-generator/test/fixtures/comments/simple-statement-comment/expected.js

@@ -1 +1 @@
-; // Trailing
+; // Trailing

packages/babel-generator/test/fixtures/comments/slash-before-leading-comment-compact/expected.js

@@ -1 +1 @@
-var foo=1/ /* leading */1;
+var foo=1/ /* leading */1;

packages/babel-generator/test/fixtures/comments/try-block-line-comment/expected.js

@@ -7,4 +7,4 @@ finally {}
 {
   try {} catch (e) {} //
   finally {}
-}
+}

packages/babel-generator/test/fixtures/comments/variable-declarator-multi-comment/expected.js

@@ -11,4 +11,4 @@ function test() {
    * Leading to VariableDeclarator
    */
   j = 20;
-}
+}

packages/babel-generator/test/fixtures/compact/assignment/expected.js

@@ -1 +1 @@
-x=1;var{y=1}=obj;
+x=1;var{y=1}=obj;

packages/babel-generator/test/fixtures/compact/binary-expressions/expected.js

@@ -1 +1 @@
-1*1;1&&1;1+ +1;x+ ++y;a+ +b*2;a+ +b*2*2*2;a- -b;1+-b;1- --b;a- -b*2;1- --t*t;
+1*1;1&&1;1+ +1;x+ ++y;a+ +b*2;a+ +b*2*2*2;a- -b;1+-b;1- --b;a- -b*2;1- --t*t;

packages/babel-generator/test/fixtures/compact/expression-statement/expected.js

@@ -1 +1 @@
-({[fieldName]:value,...rest}=values);let error;
+({[fieldName]:value,...rest}=values);let error;

packages/babel-generator/test/fixtures/compact/expression-statement/options.json

@@ -0,0 +1 @@
+{ "plugins": ["objectRestSpread"] }

packages/babel-generator/test/fixtures/compact/single-line-comment/expected.js

@@ -1,2 +1,2 @@
 // foo
-bar();
+bar();

packages/babel-generator/test/fixtures/compact/while/expected.js

@@ -1 +1 @@
-while(true)x();
+while(true)x();

packages/babel-generator/test/fixtures/edgecase/bitwise-precedence/expected.js

@@ -1,3 +1,3 @@
 x | y ^ z;
 x | y ^ z;
-(x | y) ^ z;
+(x | y) ^ z;

packages/babel-generator/test/fixtures/edgecase/floating-point/expected.js

@@ -1,2 +1,2 @@
 1.1.valueOf();
-1e+300.valueOf();
+1e+300.valueOf();

packages/babel-generator/test/fixtures/edgecase/member-expression-numeric-literals/expected.js

@@ -2,4 +2,4 @@
 2..toString();
 0x1F7.toString();
 0b111110111.toString();
-0o767.toString();
+0o767.toString();

packages/babel-generator/test/fixtures/edgecase/new-precedence/expected.js

@@ -9,4 +9,4 @@ new a().test;
 new (a().test)();
 new (a().b.c)();
 new a().b.c();
-new (a.b().c.d)();
+new (a.b().c.d)();

packages/babel-generator/test/fixtures/edgecase/one-property-with-line-terminator/expected.js

@@ -1,3 +1,3 @@
 dejavu.Class.declare({
   method2: function () {}
-});
+});

packages/babel-generator/test/fixtures/edgecase/return-with-retainlines-and-compact-option/expected.js

@@ -3,4 +3,4 @@ return(
 
 l);
 
-}
+}

packages/babel-generator/test/fixtures/edgecase/return-with-retainlines-option/expected.js

@@ -8,4 +8,4 @@ function foo() {
   return (
     1 && 2 ||
     3);
-}
+}

packages/babel-generator/test/fixtures/edgecase/unary-op/expected.js

@@ -2,4 +2,4 @@ delete delete i;
 + +i;
 !!i;
 + ++i;
-- --i;
+- --i;

packages/babel-generator/test/fixtures/edgecase/variable-declaration/expected.js

@@ -1,4 +1,4 @@
 var fact5 = function fact(n) {
   if (n <= 1) return 1;
   return n * fact(n - 1);
-}(5);
+}(5);

packages/babel-generator/test/fixtures/escapes/jsonEscape/expected.js

@@ -1 +1 @@
-"\u00A9";
+"\u00A9";

packages/babel-generator/test/fixtures/flow/array-types/expected.js

@@ -3,4 +3,4 @@ var a: ?number[];
 var a: (?number)[];
 var a: () => number[];
 var a: (() => number)[];
-var a: typeof A[];
+var a: typeof A[];

packages/babel-generator/test/fixtures/flow/boolean-literal-types/expected.js

@@ -1,2 +1,2 @@
 var foo: true;
-var bar: false;
+var bar: false;

packages/babel-generator/test/fixtures/flow/declare-exports/actual.js

@@ -22,3 +22,11 @@ declare module B {
   declare export type B = {};
   declare export interface Moon {}
 }
+
+declare module "foo" { declare export type * from "bar"; }
+declare export opaque type Foo;
+declare export opaque type Bar<T>;
+declare export opaque type Baz: Foo;
+declare export opaque type Foo<T>: Bar<T>;
+declare export opaque type Foo<T>: Bar;
+declare export opaque type Foo: Bar<T>;

packages/babel-generator/test/fixtures/flow/declare-exports/expected.js

@@ -29,4 +29,13 @@ declare export { c, d } from 'bar';
 declare module B {
   declare export type B = {};
   declare export interface Moon {}
-}
+}
+declare module "foo" {
+  declare export type * from "bar";
+}
+declare export opaque type Foo;
+declare export opaque type Bar<T>;
+declare export opaque type Baz: Foo;
+declare export opaque type Foo<T>: Bar<T>;
+declare export opaque type Foo<T>: Bar;
+declare export opaque type Foo: Bar<T>;

packages/babel-generator/test/fixtures/flow/declare-statements/actual.js

@@ -19,3 +19,7 @@ declare type B = {
 declare interface I { foo: string }
 declare interface I<T> { foo: T }
 declare module.exports: { foo: string }
+declare opaque type Foo<T>: Bar<T>;
+declare opaque type ID;
+declare opaque type num: number;
+declare opaque type NumArray;

packages/babel-generator/test/fixtures/flow/declare-statements/expected.js

@@ -38,3 +38,7 @@ declare interface I<T> {
 declare module.exports: {
   foo: string
 }
+declare opaque type Foo<T>: Bar<T>;
+declare opaque type ID;
+declare opaque type num: number;
+declare opaque type NumArray;

packages/babel-generator/test/fixtures/flow/def-site-variance/options.json

@@ -0,0 +1 @@
+{ "plugins": ["classProperties", "flow"] }

packages/babel-generator/test/fixtures/flow/null-literal-types/expected.js

@@ -1 +1 @@
-var foo: null;
+var foo: null;

packages/babel-generator/test/fixtures/flow/number-literal-types/expected.js

@@ -2,4 +2,4 @@ var a: 123;
 var a: 123.0;
 var a: 0x7B;
 var a: 0b1111011;
-var a: 0o173;
+var a: 0o173;

packages/babel-generator/test/fixtures/flow/opaque-type-alias/actual.js

@@ -0,0 +1,14 @@
+opaque type ID = string;
+opaque type Foo<T> = Bar<T>;
+opaque type Maybe<T> = _Maybe<T, *>;
+export opaque type Foo = number;
+
+opaque type union =
+ | {type: "A"}
+ | {type: "B"}
+;
+
+opaque type overloads =
+  & ((x: string) => number)
+  & ((x: number) => string)
+;

packages/babel-generator/test/fixtures/flow/opaque-type-alias/expected.js

@@ -0,0 +1,10 @@
+opaque type ID = string;
+opaque type Foo<T> = Bar<T>;
+opaque type Maybe<T> = _Maybe<T, *>;
+export opaque type Foo = number;
+opaque type union = {
+  type: "A"
+} | {
+  type: "B"
+};
+opaque type overloads = (x: string) => number & (x: number) => string;

packages/babel-generator/test/fixtures/flow/options.json

@@ -0,0 +1 @@
+{ "plugins": ["flow"] }

packages/babel-generator/test/fixtures/flow/predicates/actual.js

@@ -0,0 +1,17 @@
+declare function foo(x: mixed): boolean %checks(x !== null);
+
+declare function my_filter<T, P: $Pred<1>>(v: Array<T>, cb: P): Array<$Refine<T,P,1>>;
+
+declare function f2(x: mixed): string %checks(Array.isArray(x));
+
+function foo(x: mixed): %checks { return typeof x === "string"; }
+
+function is_string(x): boolean %checks {
+  return typeof x === "string";
+}
+
+var f = (x: mixed): %checks => typeof x === "string";
+
+const foo = (x: mixed): boolean %checks => typeof x === "string";
+
+(x): %checks => x !== null;

packages/babel-generator/test/fixtures/flow/predicates/expected.js

@@ -0,0 +1,17 @@
+declare function foo(x: mixed): boolean %checks(x !== null);
+declare function my_filter<T, P: $Pred<1>>(v: Array<T>, cb: P): Array<$Refine<T, P, 1>>;
+declare function f2(x: mixed): string %checks(Array.isArray(x));
+
+function foo(x: mixed): %checks {
+  return typeof x === "string";
+}
+
+function is_string(x): boolean %checks {
+  return typeof x === "string";
+}
+
+var f = (x: mixed): %checks => typeof x === "string";
+
+const foo = (x: mixed): boolean %checks => typeof x === "string";
+
+x: %checks => x !== null;

packages/babel-generator/test/fixtures/flow/qualified-generic-type/expected.js

@@ -1,4 +1,4 @@
 var a: A.B;
 var a: A.B.C;
 var a: A.B<T>;
-var a: typeof A.B<T>;
+var a: typeof A.B<T>;

packages/babel-generator/test/fixtures/flow/tuples/expected.js

@@ -1,4 +1,4 @@
 var a: [] = [];
 var a: [Foo<T>] = [foo];
 var a: [number] = [123];
-var a: [number, string] = [123, "duck"];
+var a: [number, string] = [123, "duck"];

packages/babel-generator/test/fixtures/flow/type-annotations/actual.js

@@ -123,3 +123,4 @@ var a: {| subtract: (x: number, ...y: Array<string>) => void |};
 var a: {| id<T>(x: T): T; |};
 function foo(numVal: number = 2) {}
 function foo(numVal?: number = 2) {}
+export type * from "foo";