Overview

Back in the day, if a user didn't provide a parserOptions.project, @typescript-eslint/parser would create one behind-the-scenes for them. This was convenient but came at severe performance cost: the parser would recompute a bunch of information for each file added.

We wish to remove the createDefaultProgram option. But, there may be some users who still rely on it. See #3627.

For now, our plan will be:

1. In the upcoming major version, rename it to deprecated__createDefaultProgram
2. Remove it in the next major version