Transform parameters after transforming generators

babel · Oct 26, 2022 · bc8915c · bc8915c
1 parent 745eacc
commit bc8915c
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Showing 8 changed files with 123 additions and 62 deletions.
diff --git a/packages/babel-compat-data/data/plugin-bugfixes.json b/packages/babel-compat-data/data/plugin-bugfixes.json
@@ -120,18 +120,6 @@
     "samsung": "13",
     "electron": "8.0"
   },
-  "transform-parameters": {
-    "chrome": "49",
-    "opera": "36",
-    "edge": "15",
-    "firefox": "53",
-    "safari": "10",
-    "node": "6",
-    "deno": "1",
-    "ios": "10",
-    "samsung": "5",
-    "electron": "0.37"
-  },
   "transform-async-to-generator": {
     "chrome": "55",
     "opera": "42",
@@ -179,5 +167,17 @@
     "ios": "10",
     "samsung": "5",
     "electron": "0.37"
+  },
+  "transform-parameters": {
+    "chrome": "49",
+    "opera": "36",
+    "edge": "15",
+    "firefox": "53",
+    "safari": "10",
+    "node": "6",
+    "deno": "1",
+    "ios": "10",
+    "samsung": "5",
+    "electron": "0.37"
   }
 }
diff --git a/packages/babel-compat-data/data/plugins.json b/packages/babel-compat-data/data/plugins.json
@@ -233,16 +233,6 @@
     "samsung": "9",
     "electron": "3.0"
   },
-  "transform-parameters": {
-    "chrome": "49",
-    "opera": "36",
-    "edge": "18",
-    "firefox": "53",
-    "node": "6",
-    "deno": "1",
-    "samsung": "5",
-    "electron": "0.37"
-  },
   "transform-async-generator-functions": {
     "chrome": "63",
     "opera": "50",
@@ -608,6 +598,16 @@
     "samsung": "5",
     "electron": "1.1"
   },
+  "transform-parameters": {
+    "chrome": "49",
+    "opera": "36",
+    "edge": "18",
+    "firefox": "53",
+    "node": "6",
+    "deno": "1",
+    "samsung": "5",
+    "electron": "0.37"
+  },
   "transform-member-expression-literals": {
     "chrome": "7",
     "opera": "12",

diff --git a/packages/babel-compat-data/scripts/data/plugin-features.js b/packages/babel-compat-data/scripts/data/plugin-features.js
@@ -9,20 +9,6 @@ const es5 = {
   "transform-reserved-words": "Miscellaneous / Unreserved words",
 };
 
-// https://github.com/babel/babel/issues/11278
-// transform-parameters should run before object-rest-spread
-const es2015Parameter = {
-  "transform-parameters": {
-    features: [
-      "default function parameters",
-      "rest parameters",
-      "destructuring, parameters / aliased defaults, arrow function",
-      "destructuring, parameters / shorthand defaults, arrow function",
-      "destructuring, parameters / duplicate identifier",
-    ],
-  },
-};
-
 const es2015 = {
   "transform-template-literals": {
     features: ["template literals"],
@@ -113,6 +99,17 @@ const es2015 = {
   "transform-regenerator": {
     features: ["generators"],
   },
+  // transform-parameters must be _after_ transform-regenertor
+  // https://github.com/babel/babel/issues/15012
+  "transform-parameters": {
+    features: [
+      "default function parameters",
+      "rest parameters",
+      "destructuring, parameters / aliased defaults, arrow function",
+      "destructuring, parameters / shorthand defaults, arrow function",
+      "destructuring, parameters / duplicate identifier",
+    ],
+  },
 };
 
 const es2016 = {
@@ -178,7 +175,6 @@ module.exports = Object.assign(
   es2021,
   es2020,
   es2019,
-  es2015Parameter,
   es2018,
   es2017,
   es2016,

diff --git a/packages/babel-plugin-transform-parameters/src/index.ts b/packages/babel-plugin-transform-parameters/src/index.ts
@@ -1,3 +1,5 @@
+import type { types as t } from "@babel/core";
+import type { NodePath } from "@babel/traverse";
 import { declare } from "@babel/helper-plugin-utils";
 import convertFunctionParams from "./params";
 import convertFunctionRest from "./rest";
@@ -15,35 +17,53 @@ export default declare((api, options: Options) => {
   // Todo(BABEL 8): Consider default it to false
   const noNewArrows = (api.assumption("noNewArrows") ?? true) as boolean;
 
+  function transformParameters(path: NodePath<t.Function>) {
+    if (
+      path.isArrowFunctionExpression() &&
+      path
+        .get("params")
+        .some(param => param.isRestElement() || param.isAssignmentPattern())
+    ) {
+      // default/rest visitors require access to `arguments`, so it cannot be an arrow
+      path.arrowFunctionToExpression({ noNewArrows });
+
+      // In some cases arrowFunctionToExpression replaces the function with a wrapper.
+      // Return early; the wrapped function will be visited later in the AST traversal.
+      if (!path.isFunctionExpression()) return false;
+    }
+
+    const convertedRest = convertFunctionRest(path);
+    const convertedParams = convertFunctionParams(path, ignoreFunctionLength);
+
+    if (convertedRest || convertedParams) {
+      // Manually reprocess this scope to ensure that the moved params are updated.
+      path.scope.crawl();
+      return true;
+    }
+    return false;
+  }
+
+  const isAsyncOrGenerator = ({ node }: NodePath<t.Function>) =>
+    node.async || node.generator;
+
   return {
     name: "transform-parameters",
 
     visitor: {
-      Function(path) {
-        if (
-          path.isArrowFunctionExpression() &&
-          path
-            .get("params")
-            .some(param => param.isRestElement() || param.isAssignmentPattern())
-        ) {
-          // default/rest visitors require access to `arguments`, so it cannot be an arrow
-          path.arrowFunctionToExpression({ noNewArrows });
-
-          // In some cases arrowFunctionToExpression replaces the function with a wrapper.
-          // Return early; the wrapped function will be visited later in the AST traversal.
-          if (!path.isFunctionExpression()) return;
-        }
-
-        const convertedRest = convertFunctionRest(path);
-        const convertedParams = convertFunctionParams(
-          path,
-          ignoreFunctionLength,
-        );
-
-        if (convertedRest || convertedParams) {
-          // Manually reprocess this scope to ensure that the moved params are updated.
-          path.scope.crawl();
-        }
+      Function: {
+        enter(path) {
+          if (!isAsyncOrGenerator(path)) transformParameters(path);
+        },
+        // We need to transform async/generator functions in `exit`,
+        // to avoid transforming parameters before that regenerator
+        // runs: https://github.com/babel/babel/issues/15012
+        // However, we still transform classic functions in `enter`,
+        // to avoid unnecessarily requeueing them.
+        exit(path) {
+          if (isAsyncOrGenerator(path)) {
+            if (transformParameters(path)) path.requeue();
+          }
+        },
       },
     },
   };

diff --git a/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/exec.js b/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/exec.js
@@ -0,0 +1,13 @@
+function* f([]) {}
+
+expect(() => f()).toThrow();
+
+let called = false;
+let run = false;
+function* g(x = (called = true)) {
+  run = true;
+}
+
+g();
+expect(called).toBe(true);
+expect(run).toBe(false);
diff --git a/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/input.js b/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/input.js
@@ -0,0 +1,3 @@
+function* f([]) {}
+
+function* g(x = fn()) {}
diff --git a/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/options.json b/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/options.json
@@ -0,0 +1,3 @@
+{
+  "presets": ["env"]
+}
diff --git a/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/output.js b/packages/babel-preset-env/test/fixtures/plugins-integration/issue-15012/output.js
@@ -0,0 +1,26 @@
+var _marked = /*#__PURE__*/babelHelpers.regeneratorRuntime().mark(f),
+  _marked2 = /*#__PURE__*/babelHelpers.regeneratorRuntime().mark(g);
+function f(_ref) {
+  var _ref2 = babelHelpers.toArray(_ref);
+  return babelHelpers.regeneratorRuntime().wrap(function f$(_context) {
+    while (1) {
+      switch (_context.prev = _context.next) {
+        case 0:
+        case "end":
+          return _context.stop();
+      }
+    }
+  }, _marked);
+}
+function g() {
+  var x = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : fn();
+  return babelHelpers.regeneratorRuntime().wrap(function g$(_context2) {
+    while (1) {
+      switch (_context2.prev = _context2.next) {
+        case 0:
+        case "end":
+          return _context2.stop();
+      }
+    }
+  }, _marked2);
+}