Fix compile errors with skip lib check

[sshquack]

Summary

Currently running the Typescript compiler on the template throws over 177 errors (See gist https://gist.github.com/sshquack/1e0d1425a10fbfa2b6eab91c8eeda235#file-rn-tsc-errors for full list of errors).

Root cause

All the errors are because tsc is finding duplicate types exposed in the node_modules. The fix is to skip the library check while doing type resolution per the compiler flag skipLibCheck https://www.typescriptlang.org/tsconfig#skipLibCheck

Before

$ yarn run tsc
node_modules/@types/react-test-renderer/node_modules/@types/react/index.d.ts(2982,14): error TS2300: Duplicate identifier 'LibraryManagedAttributes'.
node_modules/@types/react-test-renderer/node_modules/@types/react/index.d.ts(2995,13): error TS2717: Subsequent property declarations must have the same type.  Property 'a' must be of type 'DetailedHTMLProps<AnchorHTMLAttributes<HTMLAnchorElement>, HTMLAnchorElement>', but here has type 'DetailedHTMLProps<AnchorHTMLAttributes<HTMLAnchorElement>, HTMLAnchorElement>'.
node_modules/@types/react-test-renderer/node_modules/@types/react/index.d.ts(2996,13): error TS2717: Subsequent property declarations must have the same type.  Property 'abbr' must be of type 'DetailedHTMLProps<HTMLAttributes<HTMLElement>, HTMLElement>', but here has type 'DetailedHTMLProps<HTMLAttributes<HTMLElement>, HTMLElement>'.
...

Found 177 errors.

$ echo $?
1

After

$ yarn run tsc

$ echo $?
0

References

It looks like a bunch of folks have tripped over this issue according to StackOverflow. See https://stackoverflow.com/questions/54135918/typescript-and-react-native-hundreds-of-errors-from-node-modules-types-when-co

Verification

$ yarn run tsc ✔️
$ yarn run test ✔️

[emin93]

Shouldn't the exclude take care of that?

[sshquack]

@emin93 The exclude is to exclude sources and the skipLibCheck is to exclude from type resolution. They are both very different options.

This is also why skipLibCheck is set to true in the Create-React-App (CRA) TypeScript template as well.

• CRA skipLibCheck - https://github.com/facebook/create-react-app/blob/6a39607c45aa1b534799774984a7a7c2465a30de/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js#L126
• CRA discussion on skipLibCheck - Speed up TypeScript projects facebook/create-react-app#5903

So it would be good to keep this option the same as CRA and avoid surprises when invoking the tsc compiler.

[emin93]

Awesome, thanks for the clarification 🙏