During next build, the "Checking validity of types" phase should respect the typescript.tsconfigPath in next.config.js

[ellis]

Goals

During next build, the "Checking validity of types" phase should respect the typescript.tsconfigPath in next.config.js

Non-Goals

No response

Background

I maintain several tsconfig files. One of them is tsconfig.json which includes all the source code (production code, tests, development scripts, etc). Another one is tsconfig.build.json, which only excludes files that aren't relevant for the build phase. tsconfig.json has to include everything so that vscode properly handles the tests and tools. I was happy to learn about typescript.tsconfigPath, but then surprised to find that CI failed in the "Checking validity of types" phase of next build because our CI pipeline doesn't install the optionalDependencies.

Proposal

Pass the typescript.tsconfigPath to the type checking phase too.