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latest regenerator-runtime output is not strict mode es5 compliant #17440

@FBNitro

Description

@FBNitro

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  • Would you like to work on a fix?

How are you using Babel?

babel-loader (webpack)

Input code

index.ts

import axios from 'axios';

export const stuff = () => {
    return axios.get('something');
}

webpack.config.js is setup to transpile axios in this case

...
            module: {
            rules: [
                {
                    test: [/\.m?js$/, /\.tsx?$/],
                    use: {
                        loader: 'babel-loader',
                        options: {
                            presets: [['@babel/preset-env', { targets: 'ie 11' }]]
                        }
                    },
                    exclude: {
                        and: [/node_modules/],
                        not: [
                            /axios/
                        ]
                    }
                }
            ]
        },
...

Configuration file name

babel.config.js

Configuration

module.exports = function (api) {
    api.cache(true);

    const presets = [
        '@babel/typescript',
        '@babel/preset-react',
        ['@babel/preset-env', { useBuiltIns: 'usage', corejs: '{ version: 3.6, proposals: true }' }]
    ];

    return {
        presets
    };
};

Current and expected behavior

The generated output is not complaint with es5 in strict mode. Throws the following Syntax Error:

SyntaxError: Functions cannot be declared in a nested block in strict mode

The new react output for the regenerator runtime:

function _regenerator() { /*! regenerator-runtime -- Copyright (c) 2014-present, Facebook, Inc. -- license (MIT): https://github.com/babel/babel/blob/main/packages/babel-helpers/LICENSE */ var e, t, r = "function" == typeof Symbol ? Symbol : {}, n = r.iterator || "@@iterator", o = r.toStringTag || "@@toStringTag"; function i(r, n, o, i) { var c = n && n.prototype instanceof Generator ? n : Generator, u = Object.create(c.prototype); return _regeneratorDefine2(u, "_invoke", function (r, n, o) { var i, c, u, f = 0, p = o || [], y = !1, G = { p: 0, n: 0, v: e, a: d, f: d.bind(e, 4), d: function d(t, r) { return i = t, c = 0, u = e, G.n = r, a; } }; function d(r, n) { for (c = r, u = n, t = 0; !y && f && !o && t < p.length; t++) { var o, i = p[t], d = G.p, l = i[2]; r > 3 ? (o = l === n) && (u = i[(c = i[4]) ? 5 : (c = 3, 3)], i[4] = i[5] = e) : i[0] <= d && ((o = r < 2 && d < i[1]) ? (c = 0, G.v = n, G.n = i[1]) : d < l && (o = r < 3 || i[0] > n || n > l) && (i[4] = r, i[5] = n, G.n = l, c = 0)); } if (o || r > 1) return a; throw y = !0, n; } return function (o, p, l) { if (f > 1) throw TypeError("Generator is already running"); for (y && 1 === p && d(p, l), c = p, u = l; (t = c < 2 ? e : u) || !y;) { i || (c ? c < 3 ? (c > 1 && (G.n = -1), d(c, u)) : G.n = u : G.v = u); try { if (f = 2, i) { if (c || (o = "next"), t = i[o]) { if (!(t = t.call(i, u))) throw TypeError("iterator result is not an object"); if (!t.done) return t; u = t.value, c < 2 && (c = 0); } else 1 === c && (t = i.return) && t.call(i), c < 2 && (u = TypeError("The iterator does not provide a '" + o + "' method"), c = 1); i = e; } else if ((t = (y = G.n < 0) ? u : r.call(n, G)) !== a) break; } catch (t) { i = e, c = 1, u = t; } finally { f = 1; } } return { value: t, done: y }; }; }(r, o, i), !0), u; } var a = {}; function Generator() {} function GeneratorFunction() {} function GeneratorFunctionPrototype() {} t = Object.getPrototypeOf; var c = [][n] ? t(t([][n]())) : (_regeneratorDefine2(t = {}, n, function () { return this; }), t), u = GeneratorFunctionPrototype.prototype = Generator.prototype = Object.create(c); function f(e) { return Object.setPrototypeOf ? Object.setPrototypeOf(e, GeneratorFunctionPrototype) : (e.__proto__ = GeneratorFunctionPrototype, _regeneratorDefine2(e, o, "GeneratorFunction")), e.prototype = Object.create(u), e; } return GeneratorFunction.prototype = GeneratorFunctionPrototype, _regeneratorDefine2(u, "constructor", GeneratorFunctionPrototype), _regeneratorDefine2(GeneratorFunctionPrototype, "constructor", GeneratorFunction), GeneratorFunction.displayName = "GeneratorFunction", _regeneratorDefine2(GeneratorFunctionPrototype, o, "GeneratorFunction"), _regeneratorDefine2(u), _regeneratorDefine2(u, o, "Generator"), _regeneratorDefine2(u, n, function () { return this; }), _regeneratorDefine2(u, "toString", function () { return "[object Generator]"; }), (_regenerator = function _regenerator() { return { w: i, m: f }; })(); }
function _regeneratorDefine2(e, r, n, t) { var i = Object.defineProperty; try { i({}, "", {}); } catch (e) { i = 0; } _regeneratorDefine2 = function _regeneratorDefine(e, r, n, t) { if (r) i ? i(e, r, { value: n, enumerable: !t, configurable: !t, writable: !t }) : e[r] = n;else { function o(r, n) { _regeneratorDefine2(e, r, function (e) { return this._invoke(r, n, e); }); } o("next", 0), o("throw", 1), o("return", 2); } }, _regeneratorDefine2(e, r, n, t); }

you can drop the above script into jshint.com, and there will be an error saying: "Function declarations should not be placed in blocks. Use a function expression or move the statement to the top of the outer function." which I believe is the same issue I see in the browser.

The old output for regenerator-runtime (which did not error):

function _regeneratorRuntime() { "use strict"; /*! regenerator-runtime -- Copyright (c) 2014-present, Facebook, Inc. -- license (MIT): https://github.com/facebook/regenerator/blob/main/LICENSE */ _regeneratorRuntime = function _regeneratorRuntime() { return e; }; var t, e = {}, r = Object.prototype, n = r.hasOwnProperty, o = Object.defineProperty || function (t, e, r) { t[e] = r.value; }, i = "function" == typeof Symbol ? Symbol : {}, a = i.iterator || "@@iterator", c = i.asyncIterator || "@@asyncIterator", u = i.toStringTag || "@@toStringTag"; function define(t, e, r) { return Object.defineProperty(t, e, { value: r, enumerable: !0, configurable: !0, writable: !0 }), t[e]; } try { define({}, ""); } catch (t) { define = function define(t, e, r) { return t[e] = r; }; } function wrap(t, e, r, n) { var i = e && e.prototype instanceof Generator ? e : Generator, a = Object.create(i.prototype), c = new Context(n || []); return o(a, "_invoke", { value: makeInvokeMethod(t, r, c) }), a; } function tryCatch(t, e, r) { try { return { type: "normal", arg: t.call(e, r) }; } catch (t) { return { type: "throw", arg: t }; } } e.wrap = wrap; var h = "suspendedStart", l = "suspendedYield", f = "executing", s = "completed", y = {}; function Generator() {} function GeneratorFunction() {} function GeneratorFunctionPrototype() {} var p = {}; define(p, a, function () { return this; }); var d = Object.getPrototypeOf, v = d && d(d(values([]))); v && v !== r && n.call(v, a) && (p = v); var g = GeneratorFunctionPrototype.prototype = Generator.prototype = Object.create(p); function defineIteratorMethods(t) { ["next", "throw", "return"].forEach(function (e) { define(t, e, function (t) { return this._invoke(e, t); }); }); } function AsyncIterator(t, e) { function invoke(r, o, i, a) { var c = tryCatch(t[r], t, o); if ("throw" !== c.type) { var u = c.arg, h = u.value; return h && "object" == _typeof(h) && n.call(h, "__await") ? e.resolve(h.__await).then(function (t) { invoke("next", t, i, a); }, function (t) { invoke("throw", t, i, a); }) : e.resolve(h).then(function (t) { u.value = t, i(u); }, function (t) { return invoke("throw", t, i, a); }); } a(c.arg); } var r; o(this, "_invoke", { value: function value(t, n) { function callInvokeWithMethodAndArg() { return new e(function (e, r) { invoke(t, n, e, r); }); } return r = r ? r.then(callInvokeWithMethodAndArg, callInvokeWithMethodAndArg) : callInvokeWithMethodAndArg(); } }); } function makeInvokeMethod(e, r, n) { var o = h; return function (i, a) { if (o === f) throw Error("Generator is already running"); if (o === s) { if ("throw" === i) throw a; return { value: t, done: !0 }; } for (n.method = i, n.arg = a;;) { var c = n.delegate; if (c) { var u = maybeInvokeDelegate(c, n); if (u) { if (u === y) continue; return u; } } if ("next" === n.method) n.sent = n._sent = n.arg;else if ("throw" === n.method) { if (o === h) throw o = s, n.arg; n.dispatchException(n.arg); } else "return" === n.method && n.abrupt("return", n.arg); o = f; var p = tryCatch(e, r, n); if ("normal" === p.type) { if (o = n.done ? s : l, p.arg === y) continue; return { value: p.arg, done: n.done }; } "throw" === p.type && (o = s, n.method = "throw", n.arg = p.arg); } }; } function maybeInvokeDelegate(e, r) { var n = r.method, o = e.iterator[n]; if (o === t) return r.delegate = null, "throw" === n && e.iterator.return && (r.method = "return", r.arg = t, maybeInvokeDelegate(e, r), "throw" === r.method) || "return" !== n && (r.method = "throw", r.arg = new TypeError("The iterator does not provide a '" + n + "' method")), y; var i = tryCatch(o, e.iterator, r.arg); if ("throw" === i.type) return r.method = "throw", r.arg = i.arg, r.delegate = null, y; var a = i.arg; return a ? a.done ? (r[e.resultName] = a.value, r.next = e.nextLoc, "return" !== r.method && (r.method = "next", r.arg = t), r.delegate = null, y) : a : (r.method = "throw", r.arg = new TypeError("iterator result is not an object"), r.delegate = null, y); } function pushTryEntry(t) { var e = { tryLoc: t[0] }; 1 in t && (e.catchLoc = t[1]), 2 in t && (e.finallyLoc = t[2], e.afterLoc = t[3]), this.tryEntries.push(e); } function resetTryEntry(t) { var e = t.completion || {}; e.type = "normal", delete e.arg, t.completion = e; } function Context(t) { this.tryEntries = [{ tryLoc: "root" }], t.forEach(pushTryEntry, this), this.reset(!0); } function values(e) { if (e || "" === e) { var r = e[a]; if (r) return r.call(e); if ("function" == typeof e.next) return e; if (!isNaN(e.length)) { var o = -1, i = function next() { for (; ++o < e.length;) if (n.call(e, o)) return next.value = e[o], next.done = !1, next; return next.value = t, next.done = !0, next; }; return i.next = i; } } throw new TypeError(_typeof(e) + " is not iterable"); } return GeneratorFunction.prototype = GeneratorFunctionPrototype, o(g, "constructor", { value: GeneratorFunctionPrototype, configurable: !0 }), o(GeneratorFunctionPrototype, "constructor", { value: GeneratorFunction, configurable: !0 }), GeneratorFunction.displayName = define(GeneratorFunctionPrototype, u, "GeneratorFunction"), e.isGeneratorFunction = function (t) { var e = "function" == typeof t && t.constructor; return !!e && (e === GeneratorFunction || "GeneratorFunction" === (e.displayName || e.name)); }, e.mark = function (t) { return Object.setPrototypeOf ? Object.setPrototypeOf(t, GeneratorFunctionPrototype) : (t.__proto__ = GeneratorFunctionPrototype, define(t, u, "GeneratorFunction")), t.prototype = Object.create(g), t; }, e.awrap = function (t) { return { __await: t }; }, defineIteratorMethods(AsyncIterator.prototype), define(AsyncIterator.prototype, c, function () { return this; }), e.AsyncIterator = AsyncIterator, e.async = function (t, r, n, o, i) { void 0 === i && (i = Promise); var a = new AsyncIterator(wrap(t, r, n, o), i); return e.isGeneratorFunction(r) ? a : a.next().then(function (t) { return t.done ? t.value : a.next(); }); }, defineIteratorMethods(g), define(g, u, "Generator"), define(g, a, function () { return this; }), define(g, "toString", function () { return "[object Generator]"; }), e.keys = function (t) { var e = Object(t), r = []; for (var n in e) r.push(n); return r.reverse(), function next() { for (; r.length;) { var t = r.pop(); if (t in e) return next.value = t, next.done = !1, next; } return next.done = !0, next; }; }, e.values = values, Context.prototype = { constructor: Context, reset: function reset(e) { if (this.prev = 0, this.next = 0, this.sent = this._sent = t, this.done = !1, this.delegate = null, this.method = "next", this.arg = t, this.tryEntries.forEach(resetTryEntry), !e) for (var r in this) "t" === r.charAt(0) && n.call(this, r) && !isNaN(+r.slice(1)) && (this[r] = t); }, stop: function stop() { this.done = !0; var t = this.tryEntries[0].completion; if ("throw" === t.type) throw t.arg; return this.rval; }, dispatchException: function dispatchException(e) { if (this.done) throw e; var r = this; function handle(n, o) { return a.type = "throw", a.arg = e, r.next = n, o && (r.method = "next", r.arg = t), !!o; } for (var o = this.tryEntries.length - 1; o >= 0; --o) { var i = this.tryEntries[o], a = i.completion; if ("root" === i.tryLoc) return handle("end"); if (i.tryLoc <= this.prev) { var c = n.call(i, "catchLoc"), u = n.call(i, "finallyLoc"); if (c && u) { if (this.prev < i.catchLoc) return handle(i.catchLoc, !0); if (this.prev < i.finallyLoc) return handle(i.finallyLoc); } else if (c) { if (this.prev < i.catchLoc) return handle(i.catchLoc, !0); } else { if (!u) throw Error("try statement without catch or finally"); if (this.prev < i.finallyLoc) return handle(i.finallyLoc); } } } }, abrupt: function abrupt(t, e) { for (var r = this.tryEntries.length - 1; r >= 0; --r) { var o = this.tryEntries[r]; if (o.tryLoc <= this.prev && n.call(o, "finallyLoc") && this.prev < o.finallyLoc) { var i = o; break; } } i && ("break" === t || "continue" === t) && i.tryLoc <= e && e <= i.finallyLoc && (i = null); var a = i ? i.completion : {}; return a.type = t, a.arg = e, i ? (this.method = "next", this.next = i.finallyLoc, y) : this.complete(a); }, complete: function complete(t, e) { if ("throw" === t.type) throw t.arg; return "break" === t.type || "continue" === t.type ? this.next = t.arg : "return" === t.type ? (this.rval = this.arg = t.arg, this.method = "return", this.next = "end") : "normal" === t.type && e && (this.next = e), y; }, finish: function finish(t) { for (var e = this.tryEntries.length - 1; e >= 0; --e) { var r = this.tryEntries[e]; if (r.finallyLoc === t) return this.complete(r.completion, r.afterLoc), resetTryEntry(r), y; } }, catch: function _catch(t) { for (var e = this.tryEntries.length - 1; e >= 0; --e) { var r = this.tryEntries[e]; if (r.tryLoc === t) { var n = r.completion; if ("throw" === n.type) { var o = n.arg; resetTryEntry(r); } return o; } } throw Error("illegal catch attempt"); }, delegateYield: function delegateYield(e, r, n) { return this.delegate = { iterator: values(e), resultName: r, nextLoc: n }, "next" === this.method && (this.arg = t), y; } }, e; }

Environment

  System:
    OS: Windows 11 10.0.22631
  Binaries:
    Node: 20.19.2 - C:\Program Files\nodejs\node.EXE
    npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
  npmPackages:
    @babel/core: ^7.28.0 => 7.28.0
    @babel/eslint-parser: ^7.28.0 => 7.28.0
    @babel/parser: ^7.28.0 => 7.28.0
    @babel/plugin-transform-class-properties: ^7.27.1 => 7.27.1
    @babel/plugin-transform-optional-chaining: ^7.27.1 => 7.27.1
    @babel/preset-env: ^7.28.0 => 7.28.0
    @babel/preset-react: ^7.27.1 => 7.27.1
    @babel/preset-typescript: ^7.27.1 => 7.27.1
    babel-loader: ^10.0.0 => 10.0.0
    webpack: ^5.100.2 => 5.100.2

Possible solution

No response

Additional context

This was working prior upgrading which had this environment:

    @babel/core: ^7.15.5 => 7.26.10
    @babel/eslint-parser: ^7.27.1 => 7.27.1
    @babel/parser: ^7.15.7 => 7.27.0
    @babel/plugin-transform-class-properties: ^7.27.1 => 7.25.9
    @babel/plugin-transform-optional-chaining: ^7.27.1 => 7.27.1
    @babel/preset-env: ^7.26.9 => 7.26.9
    @babel/preset-react: ^7.14.5 => 7.26.3
    @babel/preset-typescript: ^7.27.0 => 7.27.0

Image of the console error:
Image

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i: regressionoutdatedA closed issue/PR that is archived due to age. Recommended to make a new issue

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