[babel 8] Remove babel 7-specific imports

babel.config.js

@@ -244,16 +244,20 @@ module.exports = function (api) {
               name: "process.env.IS_PUBLISH",
               value: bool(process.env.IS_PUBLISH),
             },
+            "flag-IS_PUBLISH",
           ],
 
-          process.env.STRIP_BABEL_8_FLAG && [
-            pluginToggleBooleanFlag,
-            {
-              name: "process.env.BABEL_8_BREAKING",
-              value: bool(process.env.BABEL_8_BREAKING),
-            },
-            "flag-BABEL_8_BREAKING",
-          ],
+          process.env.STRIP_BABEL_8_FLAG
+            ? [
+                pluginToggleBooleanFlag,
+                {
+                  name: "process.env.BABEL_8_BREAKING",
+                  attributeName: "BABEL_8_BREAKING",
+                  value: bool(process.env.BABEL_8_BREAKING),
+                },
+                "flag-BABEL_8_BREAKING",
+              ]
+            : [pluginDropBooleanImportAttribute, { name: "BABEL_8_BREAKING" }],
 
           pluginPackageJsonMacro,
 
@@ -575,7 +579,10 @@ function pluginPolyfillsOldNode({ template, types: t }) {
  * @param {import("@babel/core")} pluginAPI
  * @returns {import("@babel/core").PluginObject}
  */
-function pluginToggleBooleanFlag({ types: t }, { name, value }) {
+function pluginToggleBooleanFlag(
+  { types: t },
+  { name, attributeName = name, value }
+) {
   if (typeof value !== "boolean") throw new Error(`.value must be a boolean`);
 
   function evaluate(test) {
@@ -684,6 +691,64 @@ function pluginToggleBooleanFlag({ types: t }, { name, value }) {
           throw path.buildCodeFrameError("This check could not be stripped.");
         }
       },
+      ImportDeclaration(path) {
+        if (!path.node.attributes?.length) return;
+
+        /** @type {null | import("@babel/core").NodePath<import("@babel/core").types.ImportAttribute>} */
+        const attribute = path
+          .get("attributes")
+          .find(attr => attr.node.key.name === attributeName);
+        if (attribute == null) {
+          return;
+        }
+
+        const attributeValue = attribute.node.value.value;
+        if (attributeValue !== "true" && attributeValue !== "false") {
+          throw new path.buildCodeFrameError(
+            `${attributeName} attribute must be "true" or "false"`
+          );
+        }
+
+        if (attributeValue !== String(value)) {
+          path.remove();
+        } else {
+          attribute.remove();
+          if (path.node.attributes.length === 0) {
+            path.node.attributes = null;
+          }
+        }
+      },
+    },
+  };
+}
+
+/**
+ * @param {import("@babel/core")} pluginAPI
+ * @returns {import("@babel/core").PluginObject}
+ */
+function pluginDropBooleanImportAttribute(_babel, { name }) {
+  return {
+    visitor: {
+      ImportDeclaration(path) {
+        if (!path.node.attributes?.length) return;
+
+        const attribute = path
+          .get("attributes")
+          .find(attr => attr.node.key.name === name);
+        if (attribute == null) return;
+
+        const attributeValue = attribute.node.value.value;
+        if (attributeValue !== "true" && attributeValue !== "false") {
+          throw new path.buildCodeFrameError(
+            `${name} attribute must be "true" or "false"`
+          );
+        }
+
+        attribute.remove();
+        if (path.node.attributes.length === 0) {
+          path.node.attributes = null;
+        }
+      },
     },
   };
 }
@@ -916,6 +981,12 @@ function pluginImportMetaUrl({ types: t, template }) {
 
             // Let's just remove this declaration to unshadow the "global" cjs require.
             path.remove();
+            path.scope.crawl();
+
+            const createRequireBinding = path.scope.getBinding("createRequire");
+            if (!createRequireBinding.referenced) {
+              createRequireBinding.path.remove();
+            }
           },
 
           // import.meta.url

packages/babel-core/src/index.ts

@@ -92,8 +92,8 @@ export const DEFAULT_EXTENSIONS = Object.freeze([
   ".cjs",
 ] as const);
 
-import Module from "module";
-import * as thisFile from "./index.ts";
+import Module from "module" with { USE_ESM: "true", IS_STANDALONE: "false" };
+import * as thisFile from "./index.ts" with { USE_ESM: "true", IS_STANDALONE: "false" };
 if (USE_ESM && !IS_STANDALONE) {
   // Pass this module to the CJS proxy, so that it can be synchronously accessed.
   const cjsProxy = Module.createRequire(import.meta.url)("../cjs-proxy.cjs");

packages/babel-core/src/transformation/file/babel-7-helpers.cjs

@@ -1,4 +1,10 @@
 // TODO(Babel 8): Remove this file
 
-exports.getModuleName = () =>
-  require("@babel/helper-module-transforms").getModuleName;
+if (!process.env.BABEL_8_BREAKING) {
+  exports.getModuleName = () =>
+    require("@babel/helper-module-transforms").getModuleName;
+} else if (process.env.IS_PUBLISH) {
+  throw new Error(
+    "Internal Babel error: This file should only be loaded in Babel 7",
+  );
+}

packages/babel-core/src/transformation/file/file.ts

@@ -10,7 +10,7 @@ import semver from "semver";
 import type { NormalizedFile } from "../normalize-file.ts";
 
 // @ts-expect-error This file is `any`
-import * as babel7 from "./babel-7-helpers.cjs";
+import babel7 from "./babel-7-helpers.cjs" with { BABEL_8_BREAKING: "false" };
 
 const errorVisitor: Visitor<{ loc: t.SourceLocation | null }> = {
   enter(path, state) {

packages/babel-helper-create-class-features-plugin/src/decorators-2018-09.ts

@@ -1,20 +1,16 @@
 // TODO(Babel 8): Remove this file
+if (process.env.BABEL_8_BREAKING && process.env.IS_PUBLISH) {
+  throw new Error(
+    "Internal Babel error: This file should only be loaded in Babel 7",
+  );
+}
 
 import { types as t, template } from "@babel/core";
 import type { File, NodePath } from "@babel/core";
 import ReplaceSupers from "@babel/helper-replace-supers";
 
 type Decoratable = Extract<t.Node, { decorators?: t.Decorator[] | null }>;
 
-export function hasOwnDecorators(node: t.Class | t.ClassBody["body"][number]) {
-  // @ts-expect-error: 'decorators' not in TSIndexSignature
-  return !!node.decorators?.length;
-}
-
-export function hasDecorators(node: t.Class) {
-  return hasOwnDecorators(node) || node.body.body.some(hasOwnDecorators);
-}
-
 function prop(key: string, value?: t.Expression) {
   if (!value) return null;
   return t.objectProperty(t.identifier(key), value);

packages/babel-helper-create-class-features-plugin/src/decorators.ts

@@ -9,6 +9,15 @@ import {
 } from "./fields.ts";
 import { memoiseComputedKey } from "./misc.ts";
 
+export function hasOwnDecorators(node: t.Class | t.ClassBody["body"][number]) {
+  // @ts-expect-error: 'decorators' not in TSIndexSignature
+  return !!node.decorators?.length;
+}
+
+export function hasDecorators(node: t.Class) {
+  return hasOwnDecorators(node) || node.body.body.some(hasOwnDecorators);
+}
+
 // We inline this package
 // eslint-disable-next-line import/no-extraneous-dependencies
 import * as charCodes from "charcodes";

packages/babel-helper-create-class-features-plugin/src/features.ts

@@ -1,6 +1,6 @@
 import type { File, types as t } from "@babel/core";
 import type { NodePath } from "@babel/core";
-import { hasOwnDecorators } from "./decorators-2018-09.ts";
+import { hasOwnDecorators } from "./decorators.ts";
 
 export const FEATURES = Object.freeze({
   //classes: 1 << 0,

packages/babel-helper-create-class-features-plugin/src/index.ts

@@ -1,7 +1,5 @@
 import { types as t } from "@babel/core";
 import type { PluginAPI, PluginObject, NodePath } from "@babel/core";
-import createDecoratorTransform from "./decorators.ts";
-import type { DecoratorVersionKind } from "./decorators.ts";
 
 import semver from "semver";
 
@@ -13,7 +11,9 @@ import {
   buildCheckInRHS,
 } from "./fields.ts";
 import type { PropPath } from "./fields.ts";
-import { buildDecoratedClass, hasDecorators } from "./decorators-2018-09.ts";
+import createDecoratorTransform, { hasDecorators } from "./decorators.ts";
+import type { DecoratorVersionKind } from "./decorators.ts";
+import { buildDecoratedClass } from "./decorators-2018-09.ts" with { BABEL_8_BREAKING: "false" };
 import { injectInitialization, extractComputedKeys } from "./misc.ts";
 import {
   enableFeature,

packages/babel-plugin-transform-for-of/src/index.ts

@@ -1,7 +1,7 @@
 import { declare } from "@babel/helper-plugin-utils";
 import { template, types as t, type NodePath } from "@babel/core";
 
-import transformWithoutHelper from "./no-helper-implementation.ts";
+import transformWithoutHelper from "./no-helper-implementation.ts" with { BABEL_8_BREAKING: "false" };
 import { skipTransparentExprWrapperNodes } from "@babel/helper-skip-transparent-expression-wrappers";
 
 export interface Options {

packages/babel-plugin-transform-for-of/src/no-helper-implementation.ts

@@ -1,3 +1,9 @@
+if (process.env.BABEL_8_BREAKING && process.env.IS_PUBLISH) {
+  throw new Error(
+    "Internal Babel error: This file should only be loaded in Babel 7",
+  );
+}
+
 import { template, types as t } from "@babel/core";
 import type { PluginPass, NodePath } from "@babel/core";
 

packages/babel-plugin-transform-runtime/src/index.ts

@@ -6,7 +6,7 @@ import { hasMinVersion } from "./helpers.ts";
 import getRuntimePath, { resolveFSPath } from "./get-runtime-path/index.ts";
 
 // TODO(Babel 8): Remove this
-import babel7 from "./babel-7/index.cjs";
+import babel7 from "./babel-7/index.cjs" with { BABEL_8_BREAKING: "false" };
 
 export interface Options {
   absoluteRuntime?: boolean;

packages/babel-preset-env/src/available-plugins.ts

@@ -1,6 +1,7 @@
 /* eslint sort-keys: "error" */
 
-import otherBabel7Plugins from "./babel-7-available-plugins.cjs";
+import syntaxImportAssertions from "@babel/plugin-syntax-import-assertions" with { BABEL_8_BREAKING: "false" };
+import syntaxImportAttributes from "@babel/plugin-syntax-import-assertions" with { BABEL_8_BREAKING: "false" };
 
 import transformAsyncGeneratorFunctions from "@babel/plugin-transform-async-generator-functions";
 import transformAsyncToGenerator from "@babel/plugin-transform-async-to-generator";
@@ -185,6 +186,11 @@ if (!process.env.BABEL_8_BREAKING) {
     "syntax-private-property-in-object": syntax("privateIn"),
     "syntax-top-level-await": syntax("topLevelAwait"),
 
+    // These plugins have more logic than just enabling/disabling a feature
+    // eslint-disable-next-line sort-keys
+    "syntax-import-assertions": () => syntaxImportAssertions,
+    "syntax-import-attributes": () => syntaxImportAttributes,
+
     // These are CJS plugins that depend on a package from the monorepo, so it
     // breaks using ESM. Given that ESM builds are new enough to have this
     // syntax enabled by default, we can safely skip enabling it.
@@ -193,24 +199,6 @@ if (!process.env.BABEL_8_BREAKING) {
       USE_ESM || IS_STANDALONE
         ? () => () => ({})
         : () => require("@babel/plugin-syntax-unicode-sets-regex"),
-
-    // We need to keep these plugins because they do not simply enable a
-    // feature, but can affect the AST shape (.attributes vs .assertions).
-    // TLA is only used for local development with ESM, since we cannot
-    // require() monorepo files in that case.
-    // eslint-disable-next-line sort-keys
-    "syntax-import-assertions":
-      USE_ESM && !IS_STANDALONE
-        ? await import("@babel/plugin-syntax-import-assertions").then(
-            m => () => m.default,
-          )
-        : otherBabel7Plugins["syntax-import-assertions"],
-    "syntax-import-attributes":
-      USE_ESM && !IS_STANDALONE
-        ? await import("@babel/plugin-syntax-import-attributes").then(
-            m => () => m.default,
-          )
-        : otherBabel7Plugins["syntax-import-attributes"],
   };
 
   Object.assign(availablePlugins, legacyBabel7SyntaxPluginsLoaders);

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

@@ -24,8 +24,7 @@ import _pluginCoreJS3 from "babel-plugin-polyfill-corejs3";
 // TODO(Babel 8): Just use the default import
 const pluginCoreJS3 = _pluginCoreJS3.default || _pluginCoreJS3;
 
-// TODO(Babel 8): Remove this
-import babel7 from "./polyfills/babel-7-plugins.cjs";
+import babel7 from "./polyfills/babel-7-plugins.cjs" with { BABEL_8_BREAKING: "false" };
 
 import getTargets, {
   prettifyTargets,

packages/babel-preset-env/src/normalize-options.ts

@@ -9,8 +9,7 @@ import {
 } from "./options.ts";
 import { OptionValidator } from "@babel/helper-validator-option";
 
-// TODO(Babel 8): Remove this
-import babel7 from "./polyfills/babel-7-plugins.cjs";
+import babel7 from "./polyfills/babel-7-plugins.cjs" with { BABEL_8_BREAKING: "false" };
 
 import type {
   BuiltInsOption,

packages/babel-traverse/src/path/lib/hoister.ts

@@ -1,4 +1,4 @@
-// Remove this file in Babel 8
+// TODO: Remove this file in Babel 8
 
 import { react } from "@babel/types";
 import {

packages/babel-traverse/src/path/modification.ts

@@ -1,7 +1,6 @@
 // This file contains methods that modify the path/node in some ways.
 
 import { getCachedPaths } from "../cache.ts";
-import PathHoister from "./lib/hoister.ts";
 import NodePath from "./index.ts";
 import { _getQueueContexts, pushContext, setScope } from "./context.ts";
 import { _assertUnremoved } from "./removal.ts";
@@ -403,6 +402,7 @@ export function pushContainer<
   return path.replaceWithMultiple(verifiedNodes);
 }
 
+import PathHoister from "./lib/hoister.ts" with { BABEL_8_BREAKING: "false", USE_ESM: "false" };
 if (!process.env.BABEL_8_BREAKING && !USE_ESM) {
   /**
    * Hoist the current node to the highest scope possible and return a UID

packages/babel-types/src/converters/gatherSequenceExpressions.ts

@@ -1,5 +1,5 @@
 // TODO(Babel 8) Remove this file
-if (process.env.BABEL_8_BREAKING) {
+if (process.env.BABEL_8_BREAKING && process.env.IS_PUBLISH) {
   throw new Error(
     "Internal Babel error: This file should only be loaded in Babel 7",
   );

packages/babel-types/src/converters/toSequenceExpression.ts

@@ -1,5 +1,5 @@
 // TODO(Babel 8) Remove this file
-if (process.env.BABEL_8_BREAKING) {
+if (process.env.BABEL_8_BREAKING && process.env.IS_PUBLISH) {
   throw new Error(
     "Internal Babel error: This file should only be loaded in Babel 7",
   );

packages/babel-types/src/index.ts

@@ -109,11 +109,10 @@ export type * from "./ast-types/generated/index.ts";
 // this is used by @babel/traverse to warn about deprecated visitors
 export { default as __internal__deprecationWarning } from "./utils/deprecationWarning.ts";
 
+import toSequenceExpression from "./converters/toSequenceExpression.ts" with { BABEL_8_BREAKING: "false", USE_ESM: "false", IS_STANDALONE: "false" };
 if (!process.env.BABEL_8_BREAKING && !USE_ESM && !IS_STANDALONE) {
   // eslint-disable-next-line no-restricted-globals
-  exports.toSequenceExpression =
-    // eslint-disable-next-line no-restricted-globals
-    require("./converters/toSequenceExpression.js").default;
+  exports.toSequenceExpression = toSequenceExpression;
 }
 
 if (!process.env.BABEL_8_BREAKING && process.env.BABEL_TYPES_8_BREAKING) {