Add targets and browserslist* options to @babel/core (#12189)

packages/babel-core/package.json

@@ -39,13 +39,16 @@
   },
   "browser": {
     "./lib/config/files/index.js": "./lib/config/files/index-browser.js",
+    "./lib/config/resolve-targets.js": "./lib/config/resolve-targets-browser.js",
     "./lib/transform-file.js": "./lib/transform-file-browser.js",
     "./src/config/files/index.js": "./src/config/files/index-browser.js",
+    "./src/config/resolve-targets.js": "./src/config/resolve-targets-browser.js",
     "./src/transform-file.js": "./src/transform-file-browser.js"
   },
   "dependencies": {
     "@babel/code-frame": "workspace:^7.12.13",
     "@babel/generator": "workspace:^7.12.17",
+    "@babel/helper-compilation-targets": "workspace:^7.12.17",
     "@babel/helper-module-transforms": "workspace:^7.12.17",
     "@babel/helpers": "workspace:^7.12.17",
     "@babel/parser": "workspace:^7.12.17",

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

@@ -9,7 +9,7 @@ import {
   makeWeakCacheSync,
   type CacheConfigurator,
 } from "../caching";
-import makeAPI, { type PluginAPI } from "../helpers/config-api";
+import { makeConfigAPI, type ConfigAPI } from "../helpers/config-api";
 import { makeStaticFileCache } from "./utils";
 import loadCjsOrMjsDefault from "./module-types";
 import pathPatternToRegex from "../pattern-to-regex";
@@ -203,7 +203,7 @@ const readConfigJS = makeStrongCache(function* readConfigJS(
   let assertCache = false;
   if (typeof options === "function") {
     yield* []; // if we want to make it possible to use async configs
-    options = ((options: any): (api: PluginAPI) => {})(makeAPI(cache));
+    options = ((options: any): (api: ConfigAPI) => {})(makeConfigAPI(cache));
 
     assertCache = true;
   }

packages/babel-core/src/config/full.js

@@ -14,6 +14,7 @@ import {
   type PresetInstance,
 } from "./config-chain";
 import type { UnloadedDescriptor } from "./config-descriptors";
+import type { Targets } from "@babel/helper-compilation-targets";
 import traverse from "@babel/traverse";
 import {
   makeWeakCache,
@@ -27,7 +28,7 @@ import {
   type PluginItem,
 } from "./validation/options";
 import { validatePluginObject } from "./validation/plugins";
-import makeAPI from "./helpers/config-api";
+import { makePluginAPI } from "./helpers/config-api";
 
 import loadPrivatePartialConfig from "./partial";
 import type { ValidatedOptions } from "./validation/options";
@@ -39,6 +40,11 @@ type LoadedDescriptor = {
   alias: string,
 };
 
+type PluginContext = {
+  ...ConfigContext,
+  targets: Targets,
+};
+
 export type { InputOptions } from "./validation/options";
 
 export type ResolvedConfig = {
@@ -55,6 +61,7 @@ export type PluginPasses = Array<PluginPassList>;
 type SimpleContext = {
   envName: string,
   caller: CallerMetadata | void,
+  targets: Targets,
 };
 
 export default gensync<[any], ResolvedConfig | null>(function* loadFullConfig(
@@ -78,6 +85,11 @@ export default gensync<[any], ResolvedConfig | null>(function* loadFullConfig(
     throw new Error("Assertion failure - plugins and presets exist");
   }
 
+  const pluginContext: PluginContext = {
+    ...context,
+    targets: options.targets,
+  };
+
   const toDescriptor = (item: PluginItem) => {
     const desc = getItemDescriptor(item);
     if (!desc) {
@@ -112,12 +124,12 @@ export default gensync<[any], ResolvedConfig | null>(function* loadFullConfig(
             // in the previous pass.
             if (descriptor.ownPass) {
               presets.push({
-                preset: yield* loadPresetDescriptor(descriptor, context),
+                preset: yield* loadPresetDescriptor(descriptor, pluginContext),
                 pass: [],
               });
             } else {
               presets.unshift({
-                preset: yield* loadPresetDescriptor(descriptor, context),
+                preset: yield* loadPresetDescriptor(descriptor, pluginContext),
                 pass: pluginDescriptorsPass,
               });
             }
@@ -172,7 +184,7 @@ export default gensync<[any], ResolvedConfig | null>(function* loadFullConfig(
         const descriptor: UnloadedDescriptor = descs[i];
         if (descriptor.options !== false) {
           try {
-            pass.push(yield* loadPluginDescriptor(descriptor, context));
+            pass.push(yield* loadPluginDescriptor(descriptor, pluginContext));
           } catch (e) {
             if (e.code === "BABEL_UNKNOWN_PLUGIN_PROPERTY") {
               // print special message for `plugins: ["@babel/foo", { foo: "option" }]`
@@ -235,7 +247,7 @@ const loadDescriptor = makeWeakCache(function* (
 
     const api = {
       ...context,
-      ...makeAPI(cache),
+      ...makePluginAPI(cache),
     };
     try {
       item = yield* factory(api, options, dirname);
@@ -375,7 +387,7 @@ const validatePreset = (
  */
 function* loadPresetDescriptor(
   descriptor: UnloadedDescriptor,
-  context: ConfigContext,
+  context: PluginContext,
 ): Handler<ConfigChain | null> {
   const preset = instantiatePreset(yield* loadDescriptor(descriptor, context));
   validatePreset(preset, context, descriptor);

packages/babel-core/src/config/helpers/config-api.js

@@ -1,6 +1,8 @@
 // @flow
 
 import semver from "semver";
+import type { Targets } from "@babel/helper-compilation-targets";
+
 import { version as coreVersion } from "../../";
 import {
   assertSimpleType,
@@ -20,7 +22,9 @@ type EnvFunction = {
 
 type CallerFactory = ((CallerMetadata | void) => mixed) => SimpleType;
 
-export type PluginAPI = {|
+type TargetsFunction = () => Targets;
+
+export type ConfigAPI = {|
   version: string,
   cache: SimpleCacheConfigurator,
   env: EnvFunction,
@@ -29,9 +33,14 @@ export type PluginAPI = {|
   caller?: CallerFactory,
 |};
 
-export default function makeAPI(
-  cache: CacheConfigurator<{ envName: string, caller: CallerMetadata | void }>,
-): PluginAPI {
+export type PluginAPI = {|
+  ...ConfigAPI,
+  targets: TargetsFunction,
+|};
+
+export function makeConfigAPI<
+  SideChannel: { envName: string, caller: CallerMetadata | void },
+>(cache: CacheConfigurator<SideChannel>): ConfigAPI {
   const env: any = value =>
     cache.using(data => {
       if (typeof value === "undefined") return data.envName;
@@ -61,6 +70,22 @@ export default function makeAPI(
   };
 }
 
+export function makePluginAPI(
+  cache: CacheConfigurator<{
+    envName: string,
+    caller: CallerMetadata | void,
+    targets: Targets,
+  }>,
+): PluginAPI {
+  const targets = () =>
+    // We are using JSON.parse/JSON.stringify because it's only possible to cache
+    // primitive values. We can safely stringify the targets object because it
+    // only contains strings as its properties.
+    // Please make the Record and Tuple proposal happen!
+    JSON.parse(cache.using(data => JSON.stringify(data.targets)));
+  return { ...makeConfigAPI(cache), targets };
+}
+
 function assertVersion(range: string | number): void {
   if (typeof range === "number") {
     if (!Number.isInteger(range)) {

packages/babel-core/src/config/partial.js

@@ -14,6 +14,7 @@ import { getEnv } from "./helpers/environment";
 import {
   validate,
   type ValidatedOptions,
+  type NormalizedOptions,
   type RootMode,
 } from "./validation/options";
 
@@ -24,6 +25,7 @@ import {
   type ConfigFile,
   type IgnoreFile,
 } from "./files";
+import { resolveTargets } from "./resolve-targets";
 
 function* resolveRootMode(
   rootDir: string,
@@ -61,7 +63,7 @@ function* resolveRootMode(
 }
 
 type PrivPartialConfig = {
-  options: ValidatedOptions,
+  options: NormalizedOptions,
   context: ConfigContext,
   fileHandling: FileHandling,
   ignore: IgnoreFile | void,
@@ -115,30 +117,36 @@ export default function* loadPrivatePartialConfig(
   const configChain = yield* buildRootChain(args, context);
   if (!configChain) return null;
 
-  const options = {};
+  const merged: ValidatedOptions = {};
   configChain.options.forEach(opts => {
-    mergeOptions(options, opts);
+    mergeOptions((merged: any), opts);
   });
 
+  const options: NormalizedOptions = {
+    ...merged,
+    targets: resolveTargets(merged, absoluteRootDir, filename),
+
     // Tack the passes onto the object itself so that, if this object is
     // passed back to Babel a second time, it will be in the right structure
     // to not change behavior.
-  options.cloneInputAst = cloneInputAst;
-  options.babelrc = false;
-  options.configFile = false;
-  options.passPerPreset = false;
-  options.envName = context.envName;
-  options.cwd = context.cwd;
-  options.root = context.root;
-  options.filename =
-    typeof context.filename === "string" ? context.filename : undefined;
+    cloneInputAst,
+    babelrc: false,
+    configFile: false,
+    browserslistConfigFile: false,
+    passPerPreset: false,
+    envName: context.envName,
+    cwd: context.cwd,
+    root: context.root,
+    filename:
+      typeof context.filename === "string" ? context.filename : undefined,
 
-  options.plugins = configChain.plugins.map(descriptor =>
+    plugins: configChain.plugins.map(descriptor =>
       createItemFromDescriptor(descriptor),
-  );
-  options.presets = configChain.presets.map(descriptor =>
+    ),
+    presets: configChain.presets.map(descriptor =>
       createItemFromDescriptor(descriptor),
-  );
+    ),
+  };
 
   return {
     options,
@@ -201,7 +209,7 @@ class PartialConfig {
    * These properties are public, so any changes to them should be considered
    * a breaking change to Babel's API.
    */
-  options: ValidatedOptions;
+  options: NormalizedOptions;
   babelrc: string | void;
   babelignore: string | void;
   config: string | void;
@@ -209,7 +217,7 @@ class PartialConfig {
   files: Set<string>;
 
   constructor(
-    options: ValidatedOptions,
+    options: NormalizedOptions,
     babelrc: string | void,
     ignore: string | void,
     config: string | void,

packages/babel-core/src/config/resolve-targets-browser.js

@@ -0,0 +1,26 @@
+// @flow
+
+import type { ValidatedOptions } from "./validation/options";
+import getTargets, { type Targets } from "@babel/helper-compilation-targets";
+
+export function resolveTargets(
+  options: ValidatedOptions,
+  // eslint-disable-next-line no-unused-vars
+  root: string,
+  // eslint-disable-next-line no-unused-vars
+  filename: string | void,
+): Targets {
+  let { targets } = options;
+  if (typeof targets === "string" || Array.isArray(targets)) {
+    targets = { browsers: targets };
+  }
+  // $FlowIgnore it thinks that targets.esmodules doesn't exist.
+  if (targets && targets.esmodules) {
+    targets = { ...targets, esmodules: "intersect" };
+  }
+
+  return getTargets((targets: any), {
+    ignoreBrowserslistConfig: true,
+    browserslistEnv: options.browserslistEnv,
+  });
+}

packages/babel-core/src/config/resolve-targets.js

@@ -0,0 +1,39 @@
+// @flow
+
+import typeof * as browserType from "./resolve-targets-browser";
+import typeof * as nodeType from "./resolve-targets";
+
+// Kind of gross, but essentially asserting that the exports of this module are the same as the
+// exports of index-browser, since this file may be replaced at bundle time with index-browser.
+((({}: any): $Exact<browserType>): $Exact<nodeType>);
+
+import type { ValidatedOptions } from "./validation/options";
+import path from "path";
+import getTargets, { type Targets } from "@babel/helper-compilation-targets";
+
+export function resolveTargets(
+  options: ValidatedOptions,
+  root: string,
+  filename: string | void,
+): Targets {
+  let { targets } = options;
+  if (typeof targets === "string" || Array.isArray(targets)) {
+    targets = { browsers: targets };
+  }
+  // $FlowIgnore it thinks that targets.esmodules doesn't exist.
+  if (targets && targets.esmodules) {
+    targets = { ...targets, esmodules: "intersect" };
+  }
+
+  let configFile;
+  if (typeof options.browserslistConfigFile === "string") {
+    configFile = path.resolve(root, options.browserslistConfigFile);
+  }
+
+  return getTargets((targets: any), {
+    ignoreBrowserslistConfig: options.browserslistConfigFile === false,
+    configFile,
+    configPath: filename ?? root,
+    browserslistEnv: options.browserslistEnv,
+  });
+}

packages/babel-core/src/config/util.js

@@ -1,10 +1,10 @@
 // @flow
 
-import type { ValidatedOptions } from "./validation/options";
+import type { ValidatedOptions, NormalizedOptions } from "./validation/options";
 
 export function mergeOptions(
   target: ValidatedOptions,
-  source: ValidatedOptions,
+  source: ValidatedOptions | NormalizedOptions,
 ): void {
   for (const k of Object.keys(source)) {
     if (k === "parserOpts" && source.parserOpts) {

packages/babel-core/src/config/validation/option-assertions.js

@@ -1,5 +1,10 @@
 // @flow
 
+import {
+  isBrowsersQueryValid,
+  TargetNames,
+} from "@babel/helper-compilation-targets";
+
 import type {
   ConfigFileSearch,
   BabelrcSearch,
@@ -16,6 +21,7 @@ import type {
   NestingPath,
   CallerMetadata,
   RootMode,
+  TargetsListOrObject,
 } from "./options";
 
 export type { RootPath } from "./options";
@@ -373,3 +379,55 @@ function assertPluginTarget(loc: GeneralPath, value: mixed): PluginTarget {
   }
   return value;
 }
+
+export function assertTargets(
+  loc: GeneralPath,
+  value: mixed,
+): TargetsListOrObject {
+  if (isBrowsersQueryValid(value)) return (value: any);
+
+  if (typeof value !== "object" || !value || Array.isArray(value)) {
+    throw new Error(
+      `${msg(loc)} must be a string, an array of strings or an object`,
+    );
+  }
+
+  const browsersLoc = access(loc, "browsers");
+  const esmodulesLoc = access(loc, "esmodules");
+
+  assertBrowsersList(browsersLoc, value.browsers);
+  assertBoolean(esmodulesLoc, value.esmodules);
+
+  for (const key of Object.keys(value)) {
+    const val = value[key];
+    const subLoc = access(loc, key);
+
+    if (key === "esmodules") assertBoolean(subLoc, val);
+    else if (key === "browsers") assertBrowsersList(subLoc, val);
+    else if (!Object.hasOwnProperty.call(TargetNames, key)) {
+      const validTargets = Object.keys(TargetNames).join(", ");
+      throw new Error(
+        `${msg(
+          subLoc,
+        )} is not a valid target. Supported targets are ${validTargets}`,
+      );
+    } else assertBrowserVersion(subLoc, val);
+  }
+
+  return (value: any);
+}
+
+function assertBrowsersList(loc: GeneralPath, value: mixed) {
+  if (value !== undefined && !isBrowsersQueryValid(value)) {
+    throw new Error(
+      `${msg(loc)} must be undefined, a string or an array of strings`,
+    );
+  }
+}
+
+function assertBrowserVersion(loc: GeneralPath, value: mixed) {
+  if (typeof value === "number" && Math.round(value) === value) return;
+  if (typeof value === "string") return;
+
+  throw new Error(`${msg(loc)} must be a string or an integer number`);
+}

packages/babel-core/src/config/validation/options.js

@@ -1,5 +1,7 @@
 // @flow
 
+import type { InputTargets, Targets } from "@babel/helper-compilation-targets";
+
 import type { ConfigItem } from "../item";
 import Plugin from "../plugin";
 
@@ -23,6 +25,7 @@ import {
   assertSourceMaps,
   assertCompact,
   assertSourceType,
+  assertTargets,
   type ValidatorSet,
   type Validator,
   type OptionPath,
@@ -77,6 +80,16 @@ const NONPRESET_VALIDATORS: ValidatorSet = {
     $PropertyType<ValidatedOptions, "ignore">,
   >),
   only: (assertIgnoreList: Validator<$PropertyType<ValidatedOptions, "only">>),
+
+  targets: (assertTargets: Validator<
+    $PropertyType<ValidatedOptions, "targets">,
+  >),
+  browserslistConfigFile: (assertConfigFileSearch: Validator<
+    $PropertyType<ValidatedOptions, "browserslistConfigFile">,
+  >),
+  browserslistEnv: (assertString: Validator<
+    $PropertyType<ValidatedOptions, "browserslistEnv">,
+  >),
 };
 
 const COMMON_VALIDATORS: ValidatorSet = {
@@ -208,6 +221,11 @@ export type ValidatedOptions = {
   plugins?: PluginList,
   passPerPreset?: boolean,
 
+  // browserslists-related options
+  targets?: TargetsListOrObject,
+  browserslistConfigFile?: ConfigFileSearch,
+  browserslistEnv?: string,
+
   // Options for @babel/generator
   retainLines?: boolean,
   comments?: boolean,
@@ -241,6 +259,11 @@ export type ValidatedOptions = {
   generatorOpts?: {},
 };
 
+export type NormalizedOptions = {
+  ...$Diff<ValidatedOptions, { targets: any }>,
+  +targets: Targets,
+};
+
 export type CallerMetadata = {
   // If 'caller' is specified, require that the name is given for debugging
   // messages.
@@ -273,6 +296,11 @@ export type CompactOption = boolean | "auto";
 export type RootInputSourceMapOption = {} | boolean;
 export type RootMode = "root" | "upward" | "upward-optional";
 
+export type TargetsListOrObject =
+  | Targets
+  | InputTargets
+  | $PropertyType<InputTargets, "browsers">;
+
 export type OptionsSource =
   | "arguments"
   | "configfile"

packages/babel-core/test/config-chain.js

@@ -976,6 +976,7 @@ describe("buildConfigChain", function () {
     const getDefaults = () => ({
       babelrc: false,
       configFile: false,
+      browserslistConfigFile: false,
       cwd: process.cwd(),
       root: process.cwd(),
       envName: "development",
@@ -983,6 +984,7 @@ describe("buildConfigChain", function () {
       plugins: [],
       presets: [],
       cloneInputAst: true,
+      targets: {},
     });
     const realEnv = process.env.NODE_ENV;
     const realBabelEnv = process.env.BABEL_ENV;

packages/babel-core/test/fixtures/plugins/targets/plugin/input.js

@@ -0,0 +1 @@
+;

packages/babel-core/test/fixtures/plugins/targets/plugin/options.json

@@ -0,0 +1,4 @@
+{
+  "targets": ["firefox 64", "node 8"],
+  "plugins": ["./plugin"]
+}

packages/babel-core/test/fixtures/plugins/targets/plugin/output.js

@@ -0,0 +1,2 @@
+;
+"plugin: {\"firefox\":\"64.0.0\",\"node\":\"8.17.0\"}"

packages/babel-core/test/fixtures/plugins/targets/plugin/plugin.js

@@ -0,0 +1,14 @@
+module.exports = function (api) {
+  const { types: t } = api;
+
+  const targets = api.targets();
+
+  return {
+    visitor: {
+      Program(path) {
+        const output = t.stringLiteral(`plugin: ${JSON.stringify(targets)}`);
+        path.pushContainer("body", output);
+      },
+    },
+  };
+};

packages/babel-core/test/fixtures/plugins/targets/preset/input.js

@@ -0,0 +1 @@
+;

packages/babel-core/test/fixtures/plugins/targets/preset/options.json

@@ -0,0 +1,4 @@
+{
+  "targets": ["firefox 64", "node 8"],
+  "presets": ["./preset"]
+}

packages/babel-core/test/fixtures/plugins/targets/preset/output.js

@@ -0,0 +1,2 @@
+;
+"preset: {\"firefox\":\"64.0.0\",\"node\":\"8.17.0\"}"

packages/babel-core/test/fixtures/plugins/targets/preset/preset.js

@@ -0,0 +1,18 @@
+module.exports = function (api) {
+  const targets = api.targets();
+
+  return {
+    plugins: [plugin],
+  };
+
+  function plugin({ types: t }) {
+    return {
+      visitor: {
+        Program(path) {
+          const output = t.stringLiteral(`preset: ${JSON.stringify(targets)}`);
+          path.pushContainer("body", output);
+        },
+      },
+    };
+  }
+};

packages/babel-core/test/fixtures/targets/.browserslistrc

@@ -0,0 +1,4 @@
+chrome 80
+
+[browserslist-loading-test]
+chrome 70

packages/babel-core/test/fixtures/targets/.browserslistrc-firefox

@@ -0,0 +1 @@
+firefox 74

packages/babel-core/test/fixtures/targets/nested/.browserslistrc

@@ -0,0 +1 @@
+edge 14

packages/babel-core/test/targets.js

@@ -0,0 +1,150 @@
+import { loadOptions as loadOptionsOrig } from "../lib";
+import { join } from "path";
+
+function loadOptions(opts) {
+  return loadOptionsOrig({ cwd: __dirname, ...opts });
+}
+
+function withTargets(targets) {
+  return loadOptions({ targets });
+}
+
+describe("targets", () => {
+  it("throws if invalid type", () => {
+    expect(() => withTargets(2)).toThrow(
+      ".targets must be a string, an array of strings or an object",
+    );
+
+    expect(() => withTargets([2])).toThrow(
+      ".targets must be a string, an array of strings or an object",
+    );
+
+    expect(() => withTargets([{}])).toThrow(
+      ".targets must be a string, an array of strings or an object",
+    );
+
+    expect(() => withTargets([])).not.toThrow();
+    expect(() => withTargets({})).not.toThrow();
+  });
+
+  it("throws if invalid target", () => {
+    expect(() => withTargets({ uglify: "2.3" })).toThrow(
+      /\.targets\["uglify"\] is not a valid target/,
+    );
+
+    expect(() => withTargets({ foo: "bar" })).toThrow(
+      /\.targets\["foo"\] is not a valid target/,
+    );
+
+    expect(() => withTargets({ firefox: 71 })).not.toThrow();
+  });
+
+  it("throws if invalid version", () => {
+    expect(() => withTargets({ node: 10.1 /* or 10.10? */ })).toThrow(
+      `.targets["node"] must be a string or an integer number`,
+    );
+
+    expect(() => withTargets({ node: true })).toThrow(
+      `.targets["node"] must be a string or an integer number`,
+    );
+
+    expect(() => withTargets({ node: "10.1" })).not.toThrow();
+
+    expect(() => withTargets({ node: "current" })).not.toThrow();
+  });
+
+  it("esmodules", () => {
+    expect(() => withTargets({ esmodules: "7" })).toThrow(
+      `.targets["esmodules"] must be a boolean, or undefined`,
+    );
+
+    expect(() => withTargets({ esmodules: false })).not.toThrow();
+    expect(() => withTargets({ esmodules: true })).not.toThrow();
+  });
+
+  it("browsers", () => {
+    expect(() => withTargets({ browsers: 2 })).toThrow(
+      `.targets["browsers"] must be undefined, a string or an array of strings`,
+    );
+
+    expect(() => withTargets({ browsers: [2] })).toThrow(
+      `.targets["browsers"] must be undefined, a string or an array of strings`,
+    );
+
+    expect(() => withTargets({ browsers: {} })).toThrow(
+      `.targets["browsers"] must be undefined, a string or an array of strings`,
+    );
+
+    expect(() => withTargets({ browsers: [] })).not.toThrow();
+  });
+});
+
+describe("browserslist", () => {
+  it("loads .browserslistrc by default", () => {
+    expect(
+      loadOptions({
+        cwd: join(__dirname, "fixtures", "targets"),
+      }).targets,
+    ).toEqual({ chrome: "80.0.0" });
+  });
+
+  it("loads .browserslistrc relative to the input file", () => {
+    expect(
+      loadOptions({
+        cwd: join(__dirname, "fixtures", "targets"),
+        filename: "./nested/test.js",
+      }).targets,
+    ).toEqual({ edge: "14.0.0" });
+  });
+
+  describe("browserslistConfigFile", () => {
+    it("can disable config loading", () => {
+      expect(
+        loadOptions({
+          cwd: join(__dirname, "fixtures", "targets"),
+          browserslistConfigFile: false,
+        }).targets,
+      ).toEqual({});
+    });
+
+    it("can specify a custom file", () => {
+      expect(
+        loadOptions({
+          cwd: join(__dirname, "fixtures", "targets"),
+          browserslistConfigFile: "./.browserslistrc-firefox",
+        }).targets,
+      ).toEqual({ firefox: "74.0.0" });
+    });
+
+    it("is relative to the project root", () => {
+      expect(
+        loadOptions({
+          cwd: join(__dirname, "fixtures", "targets"),
+          root: "..",
+          filename: "./nested/test.js",
+          browserslistConfigFile: "./targets/.browserslistrc-firefox",
+        }).targets,
+      ).toEqual({ firefox: "74.0.0" });
+    });
+  });
+
+  describe("browserslistEnv", () => {
+    it("is forwarded to browserslist", () => {
+      expect(
+        loadOptions({
+          cwd: join(__dirname, "fixtures", "targets"),
+          browserslistEnv: "browserslist-loading-test",
+        }).targets,
+      ).toEqual({ chrome: "70.0.0" });
+    });
+  });
+
+  it("esmodules and browsers are intersected", () => {
+    expect(
+      withTargets({
+        esmodules: true,
+        browsers: "chrome >= 80, firefox >= 30",
+      }).targets,
+    ).toEqual({ chrome: "80.0.0", firefox: "60.0.0" });
+  });
+});

packages/babel-helper-compilation-targets/src/index.js

@@ -9,6 +9,7 @@ import {
   semverMin,
   isUnreleasedVersion,
   getLowestUnreleased,
+  getHighestUnreleased,
 } from "./utils";
 import { OptionValidator } from "@babel/helper-validator-option";
 import { browserNameMap } from "./targets";
@@ -21,9 +22,11 @@ export { prettifyTargets } from "./pretty";
 export { getInclusionReasons } from "./debug";
 export { default as filterItems, isRequired } from "./filter-items";
 export { unreleasedLabels } from "./targets";
+export { TargetNames };
+
+const ESM_SUPPORT = browserModulesData["es6.module"];
 
 const v = new OptionValidator(PACKAGE_JSON.name);
-const browserslistDefaults = browserslist.defaults;
 
 function validateTargetNames(targets: Targets): TargetsTuple {
   const validTargets = Object.keys(TargetNames);
@@ -39,8 +42,11 @@ function validateTargetNames(targets: Targets): TargetsTuple {
   return (targets: any);
 }
 
-export function isBrowsersQueryValid(browsers: Browsers | Targets): boolean {
-  return typeof browsers === "string" || Array.isArray(browsers);
+export function isBrowsersQueryValid(browsers: mixed): boolean %checks {
+  return (
+    typeof browsers === "string" ||
+    (Array.isArray(browsers) && browsers.every(b => typeof b === "string"))
+  );
 }
 
 function validateBrowsers(browsers: Browsers | void) {
@@ -149,55 +155,83 @@ function generateTargets(inputTargets: InputTargets): Targets {
   return ((input: any): Targets);
 }
 
-export default function getTargets(
-  inputTargets: InputTargets = {},
-  options: Object = {},
-): Targets {
-  let { browsers } = inputTargets;
-
-  // `esmodules` as a target indicates the specific set of browsers supporting ES Modules.
-  // These values OVERRIDE the `browsers` field.
-  if (inputTargets.esmodules) {
-    const supportsESModules = browserModulesData["es6.module"];
-    browsers = Object.keys(supportsESModules)
-      .map(browser => `${browser} ${supportsESModules[browser]}`)
-      .join(", ");
+function resolveTargets(queries: Browsers): Targets {
+  const resolved = browserslist(queries, { mobileToDesktop: true });
+  return getLowestVersions(resolved);
 }
 
-  // Parse browsers target via browserslist
-  const browsersquery = validateBrowsers(browsers);
+type GetTargetsOption = {
+  // This is not the path of the config file, but the path where start searching it from
+  configPath?: string,
+
+  // The path of the config file
+  configFile?: string,
+
+  // The env to pass to browserslist
+  browserslistEnv?: string,
+
+  // true to disable config loading
+  ignoreBrowserslistConfig?: boolean,
+};
+
+export default function getTargets(
+  inputTargets: InputTargets = {},
+  options: GetTargetsOption = {},
+): Targets {
+  let { browsers, esmodules } = inputTargets;
+
+  validateBrowsers(browsers);
 
   const input = generateTargets(inputTargets);
   let targets: TargetsTuple = validateTargetNames(input);
 
-  const shouldParseBrowsers = !!browsersquery;
+  const shouldParseBrowsers = !!browsers;
   const hasTargets = shouldParseBrowsers || Object.keys(targets).length > 0;
   const shouldSearchForConfig =
     !options.ignoreBrowserslistConfig && !hasTargets;
 
-  if (shouldParseBrowsers || shouldSearchForConfig) {
+  if (!browsers && shouldSearchForConfig) {
+    browsers =
+      browserslist.loadConfig({
+        config: options.configFile,
+        path: options.configPath,
+        env: options.browserslistEnv,
+      }) ??
       // If no targets are passed, we need to overwrite browserslist's defaults
       // so that we enable all transforms (acting like the now deprecated
       // preset-latest).
-    //
-    // Note, if browserslist resolves the config (ex. package.json), then usage
-    // of `defaults` in queries will be different since we don't want to break
-    // the behavior of "no targets is the same as preset-latest".
-    if (!hasTargets) {
-      browserslist.defaults = [];
+      [];
   }
 
-    const browsers = browserslist(browsersquery, {
-      path: options.configPath,
-      mobileToDesktop: true,
-      env: options.browserslistEnv,
-    });
+  // `esmodules` as a target indicates the specific set of browsers supporting ES Modules.
+  // These values OVERRIDE the `browsers` field.
+  if (esmodules && (esmodules !== "intersect" || !browsers)) {
+    browsers = Object.keys(ESM_SUPPORT)
+      .map(browser => `${browser} >= ${ESM_SUPPORT[browser]}`)
+      .join(", ");
+    esmodules = false;
+  }
+
+  if (browsers) {
+    const queryBrowsers = resolveTargets(browsers);
+
+    if (esmodules === "intersect") {
+      for (const browser of Object.keys(queryBrowsers)) {
+        const version = queryBrowsers[browser];
+
+        if (ESM_SUPPORT[browser]) {
+          queryBrowsers[browser] = getHighestUnreleased(
+            version,
+            semverify(ESM_SUPPORT[browser]),
+            browser,
+          );
+        } else {
+          delete queryBrowsers[browser];
+        }
+      }
+    }
 
-    const queryBrowsers = getLowestVersions(browsers);
     targets = Object.assign(queryBrowsers, targets);
-
-    // Reset browserslist defaults
-    browserslist.defaults = browserslistDefaults;
   }
 
   // Parse remaining targets

packages/babel-helper-compilation-targets/src/types.js

@@ -22,11 +22,17 @@ export type TargetsTuple = {|
   [target: Target]: string,
 |};
 
-export type Browsers = string | Array<string>;
+export type Browsers = string | $ReadOnlyArray<string>;
 
 export type InputTargets = {
   ...Targets,
 
   browsers?: Browsers,
-  esmodules?: boolean,
+
+  // When `true`, this completely replaces the `browsers` option.
+  // When `intersect`, this is intersected with the `browsers`
+  // option (giving the higher browsers as the result).
+  // TODO(Babel 8): Make `true` behave like `intersect` and
+  // remove `intersect`.
+  esmodules?: boolean | "intersect",
 };

packages/babel-helper-compilation-targets/src/utils.js

@@ -51,6 +51,14 @@ export function getLowestUnreleased(a: string, b: string, env: string): string {
   return semverMin(a, b);
 }
 
+export function getHighestUnreleased(
+  a: string,
+  b: string,
+  env: string,
+): string {
+  return getLowestUnreleased(a, b, env) === a ? b : a;
+}
+
 export function getLowestImplementedVersion(
   plugin: Targets,
   environment: Target,

packages/babel-helper-compilation-targets/test/__snapshots__/targets-parser.spec.js.snap

@@ -1,5 +1,26 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`getTargets esmodules can be intersected with a .browserslistrc file 1`] = `
+Object {
+  "chrome": "70.0.0",
+  "firefox": "60.0.0",
+}
+`;
+
+exports[`getTargets esmodules can be intersected with the browsers option 1`] = `
+Object {
+  "chrome": "70.0.0",
+  "firefox": "60.0.0",
+}
+`;
+
+exports[`getTargets esmodules explicit browser versions have the precedence over 'esmodules' 1`] = `
+Object {
+  "chrome": "20.0.0",
+  "firefox": "70.0.0",
+}
+`;
+
 exports[`getTargets esmodules returns browser supporting modules and keyed browser overrides 1`] = `
 Object {
   "android": "61.0.0",

packages/babel-helper-compilation-targets/test/fixtures/.browserslistrc

@@ -0,0 +1,2 @@
+chrome >= 70
+firefox >= 30

packages/babel-helper-compilation-targets/test/targets-parser.spec.js

@@ -1,4 +1,5 @@
 import browserslist from "browserslist";
+import { join } from "path";
 import getTargets from "..";
 
 describe("getTargets", () => {
@@ -233,6 +234,48 @@ describe("getTargets", () => {
         }),
       ).toMatchSnapshot();
     });
+
+    it("can be intersected with the browsers option", () => {
+      expect(
+        getTargets({
+          esmodules: "intersect",
+          browsers: ["chrome >= 70", "firefox >= 30"],
+        }),
+      ).toMatchSnapshot();
+    });
+
+    it("can be intersected with a .browserslistrc file", () => {
+      expect(
+        getTargets(
+          {
+            esmodules: "intersect",
+          },
+          { configPath: join(__dirname, "fixtures", "foo.js") },
+        ),
+      ).toMatchSnapshot();
+    });
+
+    it("explicit browser versions have the precedence over 'esmodules'", () => {
+      expect(
+        getTargets({
+          browsers: "chrome 5, firefox 5",
+          esmodules: "intersect",
+          chrome: 20,
+          firefox: 70,
+        }),
+      ).toMatchSnapshot();
+    });
+
+    it("'intersect' behaves like 'true' if no browsers are specified", () => {
+      expect(
+        getTargets(
+          { esmodules: "intersect" },
+          { ignoreBrowserslistConfig: true },
+        ),
+      ).toEqual(
+        getTargets({ esmodules: true }, { ignoreBrowserslistConfig: true }),
+      );
+    });
   });
 
   describe("node", () => {

packages/babel-helper-plugin-utils/src/index.js

@@ -1,19 +1,33 @@
 export function declare(builder) {
   return (api, options, dirname) => {
-    if (!api.assertVersion) {
-      // Inject a custom version of 'assertVersion' for Babel 6 and early
-      // versions of Babel 7's beta that didn't have it.
-      api = Object.assign(copyApiObject(api), {
-        assertVersion(range) {
-          throwVersionError(range, api.version);
-        },
-      });
+    let clonedApi;
+
+    for (const name of Object.keys(apiPolyfills)) {
+      if (api[name]) continue;
+
+      // TODO: Use ??= when flow lets us to do so
+      clonedApi = clonedApi ?? copyApiObject(api);
+      clonedApi[name] = apiPolyfills[name](clonedApi);
     }
 
-    return builder(api, options || {}, dirname);
+    return builder(clonedApi ?? api, options || {}, dirname);
   };
 }
 
+const apiPolyfills = {
+  // Not supported by Babel 7 and early versions of Babel 7 beta.
+  // It's important that this is polyfilled for older Babel versions
+  // since it's needed to report the version mismatch.
+  assertVersion: api => range => {
+    throwVersionError(range, api.version);
+  },
+  // This is supported starting from Babel 7.13
+  // TODO(Babel 8): Remove this polyfill
+  targets: () => () => {
+    return {};
+  },
+};
+
 function copyApiObject(api) {
   // Babel >= 7 <= beta.41 passed the API as a new object that had
   // babel/core as the prototype. While slightly faster, it also

packages/babel-preset-env/src/index.js

@@ -206,6 +206,26 @@ export const getPolyfillPlugins = ({
   return polyfillPlugins;
 };
 
+function getLocalTargets(
+  optionsTargets,
+  ignoreBrowserslistConfig,
+  configPath,
+  browserslistEnv,
+) {
+  if (optionsTargets?.esmodules && optionsTargets.browsers) {
+    console.warn(`
+@babel/preset-env: esmodules and browsers targets have been specified together.
+\`browsers\` target, \`${optionsTargets.browsers.toString()}\` will be ignored.
+`);
+  }
+
+  return getTargets(
+    // $FlowIgnore optionsTargets doesn't have an "uglify" property anymore
+    (optionsTargets: InputTargets),
+    { ignoreBrowserslistConfig, configPath, browserslistEnv },
+  );
+}
+
 function supportsStaticESM(caller) {
   return !!caller?.supportsStaticESM;
 }
@@ -225,6 +245,8 @@ function supportsTopLevelAwait(caller) {
 export default declare((api, opts) => {
   api.assertVersion(7);
 
+  const babelTargets = api.targets();
+
   const {
     bugfixes,
     configPath,
@@ -243,6 +265,16 @@ export default declare((api, opts) => {
     browserslistEnv,
   } = normalizeOptions(opts);
 
+  let targets = babelTargets;
+
+  if (
+    // If any browserslist-related option is specified, fallback to the old
+    // behavior of not using the targets specified in the top-level options.
+    opts.targets ||
+    opts.configPath ||
+    opts.browserslistEnv ||
+    opts.ignoreBrowserslistConfig
+  ) {
     if (!process.env.BABEL_8_BREAKING) {
       // eslint-disable-next-line no-var
       var hasUglifyTarget = false;
@@ -258,20 +290,13 @@ option \`forceAllTransforms: true\` instead.
       }
     }
 
-  if (optionsTargets?.esmodules && optionsTargets.browsers) {
-    console.warn(`
-@babel/preset-env: esmodules and browsers targets have been specified together.
-\`browsers\` target, \`${optionsTargets.browsers.toString()}\` will be ignored.
-`);
-  }
-
-  const targets = getTargets(
-    // $FlowIgnore optionsTargets doesn't have an "uglify" property anymore
-    (optionsTargets: InputTargets),
-    { ignoreBrowserslistConfig, configPath, browserslistEnv },
+    targets = getLocalTargets(
+      optionsTargets,
+      ignoreBrowserslistConfig,
+      configPath,
+      browserslistEnv,
     );
-  const include = transformIncludesAndExcludes(optionsInclude);
-  const exclude = transformIncludesAndExcludes(optionsExclude);
+  }
 
   const transformTargets = (
     process.env.BABEL_8_BREAKING
@@ -281,6 +306,9 @@ option \`forceAllTransforms: true\` instead.
     ? {}
     : targets;
 
+  const include = transformIncludesAndExcludes(optionsInclude);
+  const exclude = transformIncludesAndExcludes(optionsExclude);
+
   const compatData = getPluginList(shippedProposals, bugfixes);
   const shouldSkipExportNamespaceFrom =
     (modules === "auto" && api.caller?.(supportsExportNamespaceFrom)) ||

packages/babel-preset-env/test/fixtures/debug/top-level-targets-shadowed/input.mjs

@@ -0,0 +1 @@
+foo?.bar;

packages/babel-preset-env/test/fixtures/debug/top-level-targets-shadowed/options.json

@@ -0,0 +1,8 @@
+{
+  "validateLogs": true,
+  "ignoreOutput": true,
+  "targets": "chrome 80",
+  "presets": [
+    ["env", { "debug": true, "targets": "chrome 60" }]
+  ]
+}

packages/babel-preset-env/test/fixtures/debug/top-level-targets-shadowed/stdout.txt

@@ -0,0 +1,26 @@
+@babel/preset-env: `DEBUG` option
+
+Using targets:
+{
+  "chrome": "60"
+}
+
+Using modules transform: auto
+
+Using plugins:
+  proposal-numeric-separator { "chrome":"60" }
+  proposal-logical-assignment-operators { "chrome":"60" }
+  proposal-nullish-coalescing-operator { "chrome":"60" }
+  proposal-optional-chaining { "chrome":"60" }
+  proposal-json-strings { "chrome":"60" }
+  proposal-optional-catch-binding { "chrome":"60" }
+  proposal-async-generator-functions { "chrome":"60" }
+  syntax-object-rest-spread { "chrome":"60" }
+  transform-dotall-regex { "chrome":"60" }
+  proposal-unicode-property-regex { "chrome":"60" }
+  transform-named-capturing-groups-regex { "chrome":"60" }
+  proposal-export-namespace-from { "chrome":"60" }
+  transform-modules-commonjs { "chrome":"60" }
+  proposal-dynamic-import { "chrome":"60" }
+
+Using polyfills: No polyfills were added, since the `useBuiltIns` option was not set.

packages/babel-preset-env/test/fixtures/debug/top-level-targets/input.mjs

@@ -0,0 +1 @@
+foo?.bar;

packages/babel-preset-env/test/fixtures/debug/top-level-targets/options.json

@@ -0,0 +1,8 @@
+{
+  "validateLogs": true,
+  "ignoreOutput": true,
+  "targets": "chrome 80",
+  "presets": [
+    ["env", { "debug": true }]
+  ]
+}

packages/babel-preset-env/test/fixtures/debug/top-level-targets/stdout.txt

@@ -0,0 +1,23 @@
+@babel/preset-env: `DEBUG` option
+
+Using targets:
+{
+  "chrome": "80"
+}
+
+Using modules transform: auto
+
+Using plugins:
+  syntax-numeric-separator { "chrome":"80" }
+  proposal-logical-assignment-operators { "chrome":"80" }
+  syntax-nullish-coalescing-operator { "chrome":"80" }
+  syntax-optional-chaining { "chrome":"80" }
+  syntax-json-strings { "chrome":"80" }
+  syntax-optional-catch-binding { "chrome":"80" }
+  syntax-async-generators { "chrome":"80" }
+  syntax-object-rest-spread { "chrome":"80" }
+  transform-modules-commonjs { "chrome":"80" }
+  proposal-dynamic-import { "chrome":"80" }
+  proposal-export-namespace-from {}
+
+Using polyfills: No polyfills were added, since the `useBuiltIns` option was not set.

yarn.lock

@@ -131,6 +131,7 @@ __metadata:
   dependencies:
     "@babel/code-frame": "workspace:^7.12.13"
     "@babel/generator": "workspace:^7.12.17"
+    "@babel/helper-compilation-targets": "workspace:^7.12.17"
     "@babel/helper-module-transforms": "workspace:^7.12.17"
     "@babel/helper-transform-fixture-test-runner": "workspace:*"
     "@babel/helpers": "workspace:^7.12.17"