Move hoistVariables to Scope.prototype (#16644)

babel · Jul 17, 2024 · 52b21ef · 52b21ef
1 parent 054be45
commit 52b21ef
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Showing 14 changed files with 113 additions and 216 deletions.
diff --git a/packages/babel-helper-hoist-variables/.npmignore b/packages/babel-helper-hoist-variables/.npmignore
diff --git a/packages/babel-helper-hoist-variables/README.md b/packages/babel-helper-hoist-variables/README.md
diff --git a/packages/babel-helper-hoist-variables/package.json b/packages/babel-helper-hoist-variables/package.json
diff --git a/packages/babel-helper-hoist-variables/src/index.ts b/packages/babel-helper-hoist-variables/src/index.ts
diff --git a/packages/babel-helper-plugin-utils/tsconfig.json b/packages/babel-helper-plugin-utils/tsconfig.json
@@ -13,7 +13,6 @@
     "../../packages/babel-helper-compilation-targets/src/**/*.ts",
     "../../packages/babel-helper-fixtures/src/**/*.ts",
     "../../packages/babel-helper-function-name/src/**/*.ts",
-    "../../packages/babel-helper-hoist-variables/src/**/*.ts",
     "../../packages/babel-helper-module-imports/src/**/*.ts",
     "../../packages/babel-helper-module-transforms/src/**/*.ts",
     "../../packages/babel-helper-plugin-test-runner/src/**/*.ts",

diff --git a/packages/babel-plugin-proposal-async-do-expressions/package.json b/packages/babel-plugin-proposal-async-do-expressions/package.json
@@ -23,18 +23,16 @@
     "babel-plugin"
   ],
   "dependencies": {
-    "@babel/helper-hoist-variables": "workspace:^",
     "@babel/helper-plugin-utils": "workspace:^",
-    "@babel/plugin-syntax-async-do-expressions": "workspace:^"
+    "@babel/plugin-syntax-async-do-expressions": "workspace:^",
+    "@babel/traverse": "condition:BABEL_8_BREAKING ? : workspace:^"
   },
   "peerDependencies": {
     "@babel/core": "^7.13.0"
   },
   "devDependencies": {
     "@babel/core": "workspace:^",
-    "@babel/helper-plugin-test-runner": "workspace:^",
-    "@babel/traverse": "workspace:^",
-    "@babel/types": "workspace:^"
+    "@babel/helper-plugin-test-runner": "workspace:^"
   },
   "homepage": "https://babel.dev/docs/en/next/babel-plugin-proposal-async-do-expressions",
   "engines": {

diff --git a/packages/babel-plugin-proposal-async-do-expressions/src/index.ts b/packages/babel-plugin-proposal-async-do-expressions/src/index.ts
@@ -1,7 +1,5 @@
 import { declare } from "@babel/helper-plugin-utils";
 import syntaxAsyncDoExpressions from "@babel/plugin-syntax-async-do-expressions";
-import hoistVariables from "@babel/helper-hoist-variables";
-import type { types as t } from "@babel/core";
 
 export default declare(({ types: t, assertVersion }) => {
   assertVersion(REQUIRED_VERSION("^7.13.0"));
@@ -16,18 +14,17 @@ export default declare(({ types: t, assertVersion }) => {
             // non-async do expressions are handled by proposal-do-expressions
             return;
           }
-          const { scope } = path;
           // Hoist variable declaration to containing function scope
           // `async do { var x = 1; x }` -> `var x; (async() => { x = 1; return x })()`
-          hoistVariables(
-            path,
-            (id: t.Identifier) => {
-              scope.push({ id: t.cloneNode(id) });
-            },
-            "var",
-          );
-          const bodyPath = path.get("body");
+          if (!process.env.BABEL_8_BREAKING && !USE_ESM && !IS_STANDALONE) {
+            // polyfill when being run by an older Babel version
+            path.scope.hoistVariables ??=
+              // eslint-disable-next-line no-restricted-globals
+              require("@babel/traverse").Scope.prototype.hoistVariables;
+          }
+          path.scope.hoistVariables();
 
+          const bodyPath = path.get("body");
           // add implicit returns to all ending expression statements
           const completionRecords = bodyPath.getCompletionRecords();
 

diff --git a/packages/babel-plugin-transform-modules-systemjs/package.json b/packages/babel-plugin-transform-modules-systemjs/package.json
@@ -13,10 +13,10 @@
   },
   "main": "./lib/index.js",
   "dependencies": {
-    "@babel/helper-hoist-variables": "workspace:^",
     "@babel/helper-module-transforms": "workspace:^",
     "@babel/helper-plugin-utils": "workspace:^",
-    "@babel/helper-validator-identifier": "workspace:^"
+    "@babel/helper-validator-identifier": "workspace:^",
+    "@babel/traverse": "condition:BABEL_8_BREAKING ? : workspace:^"
   },
   "keywords": [
     "babel-plugin"

diff --git a/packages/babel-plugin-transform-modules-systemjs/src/index.ts b/packages/babel-plugin-transform-modules-systemjs/src/index.ts
@@ -1,5 +1,4 @@
 import { declare } from "@babel/helper-plugin-utils";
-import hoistVariables from "@babel/helper-hoist-variables";
 import { template, types as t } from "@babel/core";
 import type { PluginPass, NodePath, Scope, Visitor } from "@babel/core";
 import {
@@ -629,12 +628,19 @@ export default declare<PluginState>((api, options: Options) => {
           // @ts-expect-error todo(flow->ts): do not reuse variables
           if (moduleName) moduleName = t.stringLiteral(moduleName);
 
-          hoistVariables(path, (id, name, hasInit) => {
+          if (!process.env.BABEL_8_BREAKING && !USE_ESM && !IS_STANDALONE) {
+            // polyfill when being run by an older Babel version
+            path.scope.hoistVariables ??=
+              // eslint-disable-next-line no-restricted-globals
+              require("@babel/traverse").Scope.prototype.hoistVariables;
+          }
+
+          path.scope.hoistVariables((id, hasInit) => {
             variableIds.push(id);
-            if (!hasInit && name in exportMap) {
-              for (const exported of exportMap[name]) {
+            if (!hasInit && id.name in exportMap) {
+              for (const exported of exportMap[id.name]) {
                 exportNames.push(exported);
-                exportValues.push(scope.buildUndefinedNode());
+                exportValues.push(t.buildUndefinedNode());
               }
             }
           });

diff --git a/packages/babel-traverse/package.json b/packages/babel-traverse/package.json
@@ -19,7 +19,6 @@
     "@babel/code-frame": "workspace:^",
     "@babel/generator": "workspace:^",
     "@babel/helper-function-name": "workspace:^",
-    "@babel/helper-hoist-variables": "workspace:^",
     "@babel/parser": "workspace:^",
     "@babel/types": "workspace:^",
     "debug": "^4.3.1",

diff --git a/packages/babel-traverse/src/path/replacement.ts b/packages/babel-traverse/src/path/replacement.ts
@@ -37,7 +37,6 @@ import {
   yieldExpression,
 } from "@babel/types";
 import type * as t from "@babel/types";
-import hoistVariables from "@babel/helper-hoist-variables";
 
 /**
  * Replace a node with an array of multiple. This method performs the following steps:
@@ -261,18 +260,10 @@ export function replaceExpressionWithStatements(
   // hoist variable declaration in do block
   // `(do { var x = 1; x;})` -> `var x; (() => { x = 1; return x; })()`
   const callee = (this as ThisType).get("callee");
-  hoistVariables(
-    callee.get("body"),
-    (id: t.Identifier) => {
-      this.scope.push({ id });
-    },
-    "var",
-  );
+  callee.get("body").scope.hoistVariables(id => this.scope.push({ id }));
 
   // add implicit returns to all ending expression statements
-  const completionRecords: Array<NodePath> = (this as ThisType)
-    .get("callee")
-    .getCompletionRecords();
+  const completionRecords: Array<NodePath> = callee.getCompletionRecords();
   for (const path of completionRecords) {
     if (!path.isExpressionStatement()) continue;
 

diff --git a/packages/babel-traverse/src/scope/index.ts b/packages/babel-traverse/src/scope/index.ts
@@ -7,6 +7,7 @@ import type { BindingKind } from "./binding.ts";
 import globals from "globals";
 import {
   NOT_LOCAL_BINDING,
+  assignmentExpression,
   callExpression,
   cloneNode,
   getBindingIdentifiers,
@@ -38,6 +39,7 @@ import {
   isThisExpression,
   isUnaryExpression,
   isVariableDeclaration,
+  expressionStatement,
   matchesPattern,
   memberExpression,
   numericLiteral,
@@ -52,6 +54,7 @@ import {
   isPrivateName,
   isExportDeclaration,
   buildUndefinedNode,
+  sequenceExpression,
 } from "@babel/types";
 import * as t from "@babel/types";
 import { scope as scopeCache } from "../cache.ts";
@@ -1375,6 +1378,63 @@ class Scope {
       }
     } while ((scope = scope.parent));
   }
+
+  /**
+   * Hoist all the `var` variable to the beginning of the function/program
+   * scope where their binding will be actually defined. For exmaple,
+   *     { var x = 2 }
+   * will be transformed to
+   *     var x; { x = 2 }
+   *
+   * @param emit A custom function to emit `var` declarations, for example to
+   *   emit them in a different scope.
+   */
+  hoistVariables(
+    emit: (id: t.Identifier, hasInit: boolean) => void = id =>
+      this.push({ id }),
+  ) {
+    this.crawl();
+
+    const seen = new Set();
+    for (const name of Object.keys(this.bindings)) {
+      const binding = this.bindings[name];
+      if (!binding) continue;
+      const { path } = binding;
+      if (!path.isVariableDeclarator()) continue;
+      const { parent, parentPath } = path;
+
+      if (parent.kind !== "var" || seen.has(parent)) continue;
+      seen.add(path.parent);
+
+      let firstId;
+      const init = [];
+      for (const decl of parent.declarations) {
+        firstId ??= decl.id;
+        if (decl.init) {
+          init.push(assignmentExpression("=", decl.id, decl.init));
+        }
+
+        const ids = Object.keys(getBindingIdentifiers(decl, false, true, true));
+        for (const name of ids) {
+          emit(identifier(name), decl.init != null);
+        }
+      }
+
+      // for (var i in test)
+      if (parentPath.parentPath.isFor({ left: parent })) {
+        parentPath.replaceWith(firstId);
+      } else if (init.length === 0) {
+        parentPath.remove();
+      } else {
+        const expr = init.length === 1 ? init[0] : sequenceExpression(init);
+        if (parentPath.parentPath.isForStatement({ init: parent })) {
+          parentPath.replaceWith(expr);
+        } else {
+          parentPath.replaceWith(expressionStatement(expr));
+        }
+      }
+    }
+  }
 }
 
 type _Binding = Binding;

diff --git a/tsconfig.paths.json b/tsconfig.paths.json
@@ -53,9 +53,6 @@
       "@babel/helper-function-name": [
         "./packages/babel-helper-function-name/src"
       ],
-      "@babel/helper-hoist-variables": [
-        "./packages/babel-helper-hoist-variables/src"
-      ],
       "@babel/helper-import-to-platform-api": [
         "./packages/babel-helper-import-to-platform-api/src"
       ],