Allow tsconfig.json when input files are specified

I don’t know why the tsconfig.json is ignored even when the --project or -p option is specified. In my opinion, the right implementation should be:

• If no --project or -p option: Ignore tsconfig.json
• Otherwise: Use the configuration file specified. All the options used in the command line should overwrite the ones of the configuration file. E.g. The include/exclude keys of the tsconfig.json will be ignored when input files are specified.

[brapifra]

A pretty common practice is to have a pre-commit hook to compile only the staged files in your git project (It makes no sense to compile all the project). If you try to create this hook that runs tsc over each staged file, you won’t be able to use the tsconfig.json, as you are specifying some input files. @andy-ms

[JasonKaz]

I have a different use case that needs this as well. We have a pre-commit hook that does a quick type check (tsc -p tsconfig.json --noEmit). Currently it checks all the files specified in tsconfig.json, but it would be nice to only type check the files that were modified. We are currently using lint-staged to run linting tools on modified files, it would be great to only run the type check on the modified files too.

Like @brapifra said here, https://github.com/microsoft/TypeScript/issues/27379#issuecomment-424879463, it’s written in the docs that this should be possible, but it clearly isn’t.