Warning about ES2017+ target does not show when using Webpack plugin

[thw0rted]

🐞 Bug report

Component

@ngtools/webpack (AngularCompilerPlugin)

Is this a regression?

No

Description

#13643 added a warning message when the TS compiler is configured to emit ES2017 or higher, due to #13477. This warning is not displayed when the project is built via Webpack using AngularCompilerPlugin. I asked on angular/angular#31730 and it sounds like we need a separate ticket to track this since the linked PR and issue are both auto-closed. It doesn't look like there's a path forward on the Zone issue so this is going to keep biting people for a good while, I think.

🔬 Minimal Reproduction

Pick any project you have lying around that uses AngularCompilerPlugin, change compilerOptions.target in the tsconfig.json to ES2017, and build. If you were building it with the CLI you'd see Warning: Zone.js does not support native async/await in ES2017 on the console, but not with the plugin.

🌍 Your Environment

@ngtools-webpack 10.1.2, but I don't see any relevant changes in the recent 11+ builds.

[thw0rted]

@alan-agius4 is "freq1" really appropriate? The plugin has 1.5M weekly downloads on NPM, and while I'm sure that ES2015 is the most popular emit target by a wide margin, in late 2020 we have broad browser support for the full ES2017 feature set, including async/await.

I started my project with a lower emit years ago, but at some point I raised it to ES2018 (I do have the luxury of running in a known environment) and it seemed to "just work", so I left it that way. It wasn't until I spent 2+ days tracking down a mysterious inability to test some async code that I found the linked Zone issue. If it happened to me, it's happening to a nontrivial percentage of your users, and even 1% of 1.5M users is hardly "only a handful, who observe it rarely".

[alan-agius4]

Hi @thw0rted,

Most of the package downloads comes from @angular/cli users. Approximately 8% of the users use @ngtools/webpack without Angular CLI. That 8% goes down even more when taking into account users that target only ES2017+.

That said, I do have a PR in flight for this #19228

[thw0rted]

Sorry, Alan, I was going by the NPM page -- I didn't realize those numbers reflected usage other than via Webpack. (Or, I guess, the CLI uses Webpack under the hood?) Anyway, it looks like this was a quick fix, which is great news. Thanks!

[alan-agius4]

No worries @thw0rted, yes the CLI does use Webpack under the hood.

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