Revert "Improve output when wrapping functions" (#15979)

* Add a test

* Revert "Improve output when wrapping functions (e.g. `async` functions) (#15922)"

This reverts commit b9a2244.

* Update snapshot

Author: jjonescz

packages/babel-helper-remap-async-to-generator/src/index.ts

@@ -1,3 +1,5 @@
+/* @noflow */
+
 import type { NodePath } from "@babel/traverse";
 import wrapFunction from "@babel/helper-wrap-function";
 import annotateAsPure from "@babel/helper-annotate-as-pure";
@@ -63,7 +65,7 @@ export default function (
     path.parentPath.isObjectProperty() ||
     path.parentPath.isClassProperty();
 
-  if (!isProperty && !isIIFE && path.isCallExpression()) {
+  if (!isProperty && !isIIFE && path.isExpression()) {
     annotateAsPure(path);
   }
 

packages/babel-helper-wrap-function/src/index.ts

@@ -10,18 +10,56 @@ import {
   isRestElement,
   returnStatement,
   isCallExpression,
-  cloneNode,
-  toExpression,
 } from "@babel/types";
 import type * as t from "@babel/types";
 
-const buildWrapper = template.statement(`
-  function NAME(PARAMS) {
-    return (REF = REF || FUNCTION).apply(this, arguments);
+type ExpressionWrapperBuilder<ExtraBody extends t.Node[]> = (
+  replacements?: Parameters<ReturnType<typeof template.expression>>[0],
+) => t.CallExpression & {
+  callee: t.FunctionExpression & {
+    body: {
+      body: [
+        t.VariableDeclaration & {
+          declarations: [
+            { init: t.FunctionExpression | t.ArrowFunctionExpression },
+          ];
+        },
+        ...ExtraBody,
+      ];
+    };
+  };
+};
+
+const buildAnonymousExpressionWrapper = template.expression(`
+  (function () {
+    var REF = FUNCTION;
+    return function NAME(PARAMS) {
+      return REF.apply(this, arguments);
+    };
+  })()
+`) as ExpressionWrapperBuilder<
+  [t.ReturnStatement & { argument: t.FunctionExpression }]
+>;
+
+const buildNamedExpressionWrapper = template.expression(`
+  (function () {
+    var REF = FUNCTION;
+    function NAME(PARAMS) {
+      return REF.apply(this, arguments);
+    }
+    return NAME;
+  })()
+`) as ExpressionWrapperBuilder<
+  [t.FunctionDeclaration, t.ReturnStatement & { argument: t.Identifier }]
+>;
+
+const buildDeclarationWrapper = template.statements(`
+  function NAME(PARAMS) { return REF.apply(this, arguments); }
+  function REF() {
+    REF = FUNCTION;
+    return REF.apply(this, arguments);
   }
-`) as (
-  replacements: Parameters<ReturnType<typeof template.expression>>[0],
-) => t.FunctionDeclaration;
+`);
 
 function classOrObjectMethod(
   path: NodePath<t.ClassMethod | t.ClassPrivateMethod | t.ObjectMethod>,
@@ -102,32 +140,40 @@ function plainFunction(
     params.push(path.scope.generateUidIdentifier("x"));
   }
 
-  const ref = path.scope.generateUidIdentifier(
-    functionId ? functionId.name : "ref",
-  );
-
-  let wrapper: t.Function = buildWrapper({
-    NAME: functionId,
-    REF: ref,
+  const wrapperArgs = {
+    NAME: functionId || null,
+    REF: path.scope.generateUidIdentifier(functionId ? functionId.name : "ref"),
     FUNCTION: built,
     PARAMS: params,
-  });
-
-  if (!isDeclaration) {
-    wrapper = toExpression(wrapper);
-    nameFunction({
-      node: wrapper,
-      parent: (path as NodePath<t.FunctionExpression>).parent,
-      scope: path.scope,
-    });
-  }
+  };
 
-  if (isDeclaration || wrapper.id || (!ignoreFunctionLength && params.length)) {
-    path.replaceWith(wrapper);
-    path.parentPath.scope.push({ id: cloneNode(ref) });
+  if (isDeclaration) {
+    const container = buildDeclarationWrapper(wrapperArgs);
+    path.replaceWith(container[0]);
+    path.insertAfter(container[1]);
   } else {
-    // we can omit this wrapper as the conditions it protects for do not apply
-    path.replaceWith(built);
+    let container;
+
+    if (functionId) {
+      container = buildNamedExpressionWrapper(wrapperArgs);
+    } else {
+      container = buildAnonymousExpressionWrapper(wrapperArgs);
+
+      const returnFn = container.callee.body.body[1].argument;
+      nameFunction({
+        node: returnFn,
+        parent: (path as NodePath<t.FunctionExpression>).parent,
+        scope: path.scope,
+      });
+      functionId = returnFn.id;
+    }
+
+    if (functionId || (!ignoreFunctionLength && params.length)) {
+      path.replaceWith(container);
+    } else {
+      // we can omit this wrapper as the conditions it protects for do not apply
+      path.replaceWith(built);
+    }
   }
 }
 

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/integration/async-to-generator/output.js

@@ -1,6 +1,8 @@
-var _fn;
 function fn() {
-  return (_fn = _fn || babelHelpers.asyncToGenerator(function* () {
+  return _fn.apply(this, arguments);
+}
+function _fn() {
+  _fn = babelHelpers.asyncToGenerator(function* () {
     yield 0;
     try {
       var _stack = [];
@@ -12,5 +14,6 @@ function fn() {
     } finally {
       yield babelHelpers.dispose(_stack, _error, _hasError);
     }
-  })).apply(this, arguments);
+  });
+  return _fn.apply(this, arguments);
 }

packages/babel-plugin-proposal-function-sent/test/fixtures/function-sent/basic/output.js

@@ -1,7 +1,10 @@
-var _gen;
 function gen() {
-  return (_gen = _gen || babelHelpers.skipFirstGeneratorNext(function* () {
+  return _gen.apply(this, arguments);
+}
+function _gen() {
+  _gen = babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     let sent = _functionSent;
-  })).apply(this, arguments);
+  });
+  return _gen.apply(this, arguments);
 }

packages/babel-plugin-proposal-function-sent/test/fixtures/generator-kinds/async-generator/output.js

@@ -1,7 +1,10 @@
-var _foo;
 function foo() {
-  return (_foo = _foo || babelHelpers.wrapAsyncGenerator(babelHelpers.skipFirstGeneratorNext(function* () {
+  return _foo.apply(this, arguments);
+}
+function _foo() {
+  _foo = babelHelpers.wrapAsyncGenerator(babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     _functionSent = yield babelHelpers.awaitAsyncGenerator(_functionSent);
-  }))).apply(this, arguments);
+  }));
+  return _foo.apply(this, arguments);
 }

packages/babel-plugin-proposal-function-sent/test/fixtures/generator-kinds/export-default-anonymous/output.mjs

@@ -1,7 +1,10 @@
-var _ref;
 export default function () {
-  return (_ref = _ref || babelHelpers.skipFirstGeneratorNext(function* () {
+  return _ref.apply(this, arguments);
+}
+function _ref() {
+  _ref = babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     return _functionSent;
-  })).apply(this, arguments);
+  });
+  return _ref.apply(this, arguments);
 }

packages/babel-plugin-proposal-function-sent/test/fixtures/generator-kinds/export-default-named/output.mjs

@@ -1,7 +1,10 @@
-var _gen;
 export default function gen() {
-  return (_gen = _gen || babelHelpers.skipFirstGeneratorNext(function* () {
+  return _gen.apply(this, arguments);
+}
+function _gen() {
+  _gen = babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     return _functionSent;
-  })).apply(this, arguments);
+  });
+  return _gen.apply(this, arguments);
 }

packages/babel-plugin-proposal-function-sent/test/fixtures/generator-kinds/export/output.mjs

@@ -1,7 +1,10 @@
-var _gen;
 export function gen() {
-  return (_gen = _gen || babelHelpers.skipFirstGeneratorNext(function* () {
+  return _gen.apply(this, arguments);
+}
+function _gen() {
+  _gen = babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     return _functionSent;
-  })).apply(this, arguments);
+  });
+  return _gen.apply(this, arguments);
 }

packages/babel-plugin-proposal-function-sent/test/fixtures/generator-kinds/expression-named/output.js

@@ -1,7 +1,10 @@
-var _gen;
-const foo = function gen() {
-  return (_gen = _gen || babelHelpers.skipFirstGeneratorNext(function* () {
+const foo = function () {
+  var _gen = babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     return _functionSent;
-  })).apply(this, arguments);
-};
+  });
+  function gen() {
+    return _gen.apply(this, arguments);
+  }
+  return gen;
+}();

packages/babel-plugin-proposal-function-sent/test/fixtures/generator-kinds/statement/output.js

@@ -1,7 +1,10 @@
-var _gen;
 function gen() {
-  return (_gen = _gen || babelHelpers.skipFirstGeneratorNext(function* () {
+  return _gen.apply(this, arguments);
+}
+function _gen() {
+  _gen = babelHelpers.skipFirstGeneratorNext(function* () {
     let _functionSent = yield;
     return _functionSent;
-  })).apply(this, arguments);
+  });
+  return _gen.apply(this, arguments);
 }