alexandradeas / typescript-workspace-pollution

Demo of typescript compiler options being carried across yarn workspaces

Overview

A demo TS project to show how one yarn workspace depending on another workspace with weaker compiler options fails type checking.

workspace-a is a library with no additional type configuration enabled (the most important being that 'noImplicitAny' is not enabled). This library exposes one function log. log does not provide any type annotations and therefore its type is inferred as const log: (msg: any) => void.

workspace-b is an application with the 'strict' compiler option enabled. This means that the 'noImplicitAny' rule is enabled. workspace-b has a depenency on workspace-a. workspace-b has 'node_modules' excluded as part of the tsconfig.json

The Issue

When building workspace-b TypeScript returns an error for workspace-a#log because its parameter is implicitly typed as any.

../workspace-a/src/index.ts:1:21 - error TS7006: Parameter 'msg' implicitly has an 'any' type.

1 export const log = (msg) => {
                      ~~~


Found 1 error.

error Command failed with exit code 2.

Steps to reproduce

yarn install
cd workspace-b
yarn tsc