parcel: Unexpected "With `useBuiltins` option, required direct setting of `corejs` option" with default configuration

🐛 bug report

Calling parcel build <entry point> with all default configuration results in a warning from @babel/preset-env.

🎛 Configuration (.babelrc, package.json, cli command)

.babelrc: none
package.json:

{
  "name": "test",
  "version": "1.0.0",
  "license": "MIT",
  "devDependencies": {
    "parcel-bundler": "^1.12.2"
  }
}

CLI command: yarn run parcel build src/index.html

🤔 Expected Behavior

The build should complete with no errors or warnings

😯 Current Behavior

The build completes, but it emits the following warning: With `useBuiltIns` option, required direct setting of `corejs` option

💁 Possible Solution

This warning appears to come from @babel/preset-env. It seems like it might be possible to avoid by specifying corejs appropriately in transforms/babel.js

🔦 Context

I’m trying to bootstrap a project which requires no extra configuration than what Parcel comes with out of the box. It would be helpful for this warning to be resolved without having to add extra non-functional Babel configuration (several attempts at configuring correctly have failed).

💻 Code Sample

The following files with the addition of the above configuration should be enough to reproduce the issue.

src/index.html:

<!DOCTYPE html>
<html>
  <body>
    <div id="root">test</div>
    <script src="./index.js"></script>
  </body>
</html>

src/index.js:

document.getElementById('root').append('more test')

🌍 Your Environment

Software	Version(s)
Parcel	1.12.2
Node	11.9.0
npm/Yarn	1.13.0
Operating System	macOS 10.14.3

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 28
Comments: 46 (12 by maintainers)

Commits related to this issue

Update package.json (@babel/core@7.4.0 issue) please check these resources below on the reasoning behind this problematic babel bug: - https://stackoverflow.com/questions/55251983/what-does-this-e... — committed to oakromulo/vue-cli by oakromulo 5 years ago
bug #545 Set useBuiltIns to false by default and allow to set core-js version (Lyrkan) This PR was merged into the master branch. Discussion ---------- Set useBuiltIns to false by default and allow... — committed to symfony/webpack-encore by weaverryan 5 years ago
Pin parcel to 1.12.3 Several warnings are emitted during build due to https://github.com/parcel-bundler/parcel/issues/2819 so pin parcel to a version without the issues. — committed to coocos/toy-tracer by coocos 5 years ago

Most upvoted comments

I’m not sure about the core-js thing. It’s a warning, but people tend to freak out about warnings, and perhaps other bugs in babel 7.4 are getting conflated with this warning.

Ok, let me explain the current situation: @babel/preset-env generates imports to core-js. Let’s assume that it only generates imports to core-js@2, that it doesn’t know about core-js@3. We can make this assumption because core-js@2 is the default behavior.

The fact that it generates those imports means that users need to have "core-js": "^2.0.0" in their package.json’s dependencies. Since almost every node project which uses npm already has core-js as a dependency of a dependency (it has three times the downlaods of react or of webpack), and npm hoist packages to the top when possible, so node_modules/core-js always existed even if it wasn’t defined as a dependency: even if it was documented, people didn’t notice that they where depending on a package which they hadn’t specified.

Yesterday core-js@3 was released. If any package in your dependency tree (for example, as you noted in https://github.com/parcel-bundler/parcel/issues/2819#issuecomment-474982867, Babel), your app will have both core-js@2 and core-js@3 in your dependencies three and npm can choose which to hoist. If it decides to hoist core-js@3, all the imports pointing to core-js@2 will be broken. It is a major version of the package, so it isn’t unexpected that it breaks something. For this reason, users must have core-js@2 in their dependencies: if they are relying on a package, it needs to be explicit or major updates will be done when any of the dependencies updates its subdependency.

Even if the necessity to npm install --save core-js has been documented since Babel 6, users didn’t do it. We needed to do something to make them aware about it, so we asked them not to rely on the default behavior but to be explicit about it: corejs: 2 is a way of saying “I know I’m using core-js@2”. I know, the warning message doesn’t explain it and we will soon update it (https://github.com/babel/babel/pull/9716).

An example of a project which relied on core-js without it being installed is angular-cli: https://github.com/angular/angular-cli/issues/13954#issuecomment-474827906

Relying on npm hoisting won’t work anymore, and we need to make people aware of the presence of core-js in their project.

I don’t know if parcel does analyse node_modules, but if it does the only way to proper fix this issue is to set the corejs option you pass to preset env based on what will be bundled: corejs: require("core-js/package.json").version.

Thanks for reporting the other issue, I’m looking at it.

nicolo-ribaudo on Mar 20, 2019

I downgraded all babel packages to < 7.4 in https://github.com/parcel-bundler/parcel/commit/53c09b3cfa3a14bc0dc9875950b31e43d4a9a2e4 while we get this figured out. Published parcel v1.12.3.

devongovett on Mar 20, 2019

See this stackoverflow question for some solutions/approaches.

loopmode on Mar 20, 2019

Confirmed that this issue is solved with 1.12.3 of parcel

tmbrwn on May 16, 2019

'@babel/plugin-transform-runtime’can’t have the corejs configuration option, although the source code in its version 7.4.0 has this option, but setting it will make an error!!!

Can you show an example which explains the problem? It should work.

@Maximilianos Doesn’t Babel 7.4.0 work if you do not upgrade to core-js@3?

I only installed version 3.0.0 of “core-js”.(npm i -g core-js) No “core-js@2”!!!

My version of “core-js” in “package.json”: “core-js”: “^3.0.0” , “core-js-compat”: “^3.0.0” , “core-js-pure”: “^3.0.0”

and, My Babel configuration has the following information: ‘@babel/preset-env’, { targets: { browsers: [ ‘>= 10%’, ‘cover 95%’, ‘since 2017-01-01’, ‘iOS >= 10’, ‘Safari >= 10’, ‘Edge >= 16’, ‘Opera >= 47’, ‘Android >= 56’, ‘Chrome >= 56’, ‘ChromeAndroid >= 56’, ‘Firefox ESR’, ‘Firefox >= 54’, ‘FirefoxAndroid >= 54’, ‘last 2 Baidu major versions’, ‘last 2 OperaMini major versions’, ‘last 2 QQAndroid major versions’, ‘last 2 UCAndroid major versions’, ‘last 2 OperaMobile major versions’, ‘last 2 Samsung major versions’, ‘last 2 BlackBerry major versions’, ‘last 2 major versions’, ‘last 2 versions’, ‘not ie <= 11’, ‘not ie_mob <= 11’, ‘not dead’ ], safari: ‘tp’, esmodules: false }, modules: false, spec: false, loose: true, shippedProposals: true, useBuiltIns: ‘usage’ } ‘@babel/plugin-transform-runtime’, { helpers: true, regenerator: true, useESModules: true }

When the @babel/preset-env and @babel/plugin-transform-runtime options are set the “corejs” option, the value is: corejs: { version: 3, proposals: true } Report wrong!!! The error message is as follows: error1 1.txt

If only the “corejs” option of “@babel/plugin-transform-runtime” is set, and the value is: corejs: { version: 3, proposals: true } And there is no “corejs” option for “@babel/preset-env”!!! However, the value of the “useBuiltIns” option of “@babel/preset-env” is “usage”. It will go wrong.!!! The error message is as follows: 只启用transform1 只启用transform2 只启用transform.txt

But if me just set the “corejs” option of “@babel/preset-env”, the value is: corejs: { version: 3, proposals: true } No “corejs” option is set for “@babel/plugin-transform-runtime”! Then my project will compile successfully!!!

LP1994 on Mar 21, 2019

Also, 53c09b3 will only work until some other dependency will depend on core-js@3. As you can see in https://github.com/parcel-bundler/parcel/issues/2819#issuecomment-474898805, it’s not a problem specific of v7.4.

nicolo-ribaudo on Mar 20, 2019

Sorry, just realized that 1.12.3 only rolled back the version of babel. I think I should keep this open until there is a definitive solution.

tmbrwn on May 16, 2019

I just use these. you can also try update parcel,it maybe deal this bug

ewqazxc on Apr 24, 2019

https://github.com/babel/babel/issues/9720

devongovett on Mar 20, 2019

I believe that is probably a separate issue with babel 7.4, unrelated to the warning.

devongovett on Mar 20, 2019

(btw this overriding behavior is bad and it’s going away in parcel 2, but it’s what we have right now)

devongovett on Mar 20, 2019

Did you try to npm install --save core-js@2?

nicolo-ribaudo on Mar 20, 2019

“useBuiltIns now requires direct setting of corejs version option, without it will be used 2 by default and shown deprecation warning.” merged 3 hours ago at the time of writing.

Didn’t realize the change was so recent. Looks like Babel is making a soft API change in 7.4.0. I doubt they’ll turn back on that, so unfortunately I think it has become a Parcel issue.

tmbrwn on Mar 19, 2019