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Typescript prevents compilation #5937
Description
Is this a bug report?
Yes
Did you try recovering your dependencies?
$ yarn --version
1.12.3
Environment
Environment Info:
System:
OS: macOS 10.14.1
CPU: x64 Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
Binaries:
Node: 11.0.0 - /usr/local/bin/node
Yarn: 1.12.3 - ~/.yarn/bin/yarn
npm: 6.4.1 - ~/Desktop/Radar/frontend/node_modules/.bin/npm
Browsers:
Chrome: 70.0.3538.110
Safari: 12.0.1
npmPackages:
@types/react: ^16.7.10 => 16.7.10
@types/react-dom: ^16.0.11 => 16.0.11
react: ^16.6.3 => 16.6.3
react-dom: ^16.6.3 => 16.6.3
react-scripts: 2.1.1 => 2.1.1
npmGlobalPackages:
create-react-app: Not Found
Expected Behavior
I expect yarn start to compile even with Typescript errors. Typescript is, by my understanding of CRA's philosophy, just an extra layer but won't prevent compilation. yarn start worked fine with Typescript errors a few days ago, not sure what I changed but I came into Typescript pre-2.1.0 and I may have updated accidentally.
Actual Behavior
I get a Typescript compile error. Using a reproducible demo:
I create a simple reproducible demo:
$ yarn create react-app my-app --scripts-version=react-scripts-ts
$ cd my-app
$ yarn add react-bootstrap@next bootstrap
with the following index.tsx:
[imports]
import Form from 'react-bootstrap/es/Form'
...
render() {
return (
...
<Form></Form>
....
)
}
and I get the following error after yarn start:
(3,18): Could not find a declaration file for module 'react-bootstrap/es/Form'. '/private/tmp/my-app/node_modules/react-bootstrap/es/Form.js' implicitly has an 'any' type.
Try `npm install @types/react-bootstrap` if it exists or add a new declaration (.d.ts) file containing `declare module 'react-bootstrap/es/Form';`
I've been digging through the webpack configuration (slowly) and it seems like this might be related?
Activity
Timer commentedon Nov 30, 2018
This is an actual TypeScript error. You need to follow the instructions given by the TypeScript compiler or turn off strict mode.
wafisher commentedon Dec 1, 2018
I just want to confirm: Typescript errors will prevent compilation, is that correct?
If this is a feature not a bug, would you mind if I added something to the docs mentioning that — I think most people expect Typescript not to actually prevent compilation unless there's a parsing error.
Timer commentedon Dec 1, 2018
Yes.
Can you explain the reasoning behind this? If there's an error in your code, why would you want it to run?
wafisher commentedon Dec 1, 2018
Well, there's an error in the Typescript, but not in what would be the compiled JS.
The change just caught me by surprise. When I added Typescript a few months ago to my CRA project, the behavior was Typescript checking in my IDE/console but it would still compile with errors (strip out types) and
yarn rundidn't know anything about types.I understand the decision you've made — not arguing against that. Just saying I for one was surprised by this behavior and would not have spent time filing this bug if I had realized it wasn't a bug at all (i.e. the docs had said this is what happens), which might be an indication that others will be confused.
Timer commentedon Dec 1, 2018
We've never supported TypeScript in the past -- can you elaborate on your previous setup?
I appreciate you bringing this up though, I know we have a lot of work to do on improving our docs. :-)
wafisher commentedon Dec 3, 2018
Actually, I read the ^2.1.0 docs while not being on 2.1.0 (without realizing it didn't apply to me) so I ran:
Which probably triggered IntelliJ to see I had .ts/.tsx files as I opened them, compile them (while editing) into .js files which were picked up in the compilation. So effectively a flow that didn't compile Typescript synchronously.
I'm using
async: truehere to great success right now, FWIW.Timer commentedon Dec 3, 2018
We have a PR to speed this up: #5903