What problem does this feature solve?

ESLint has a --max-warnings command line options that triggers an return code > 0 when eslint detects more than n warnings.

This is really useful for example to allow developpers to work without worrying about eslint warnings, but make the CI build fail if there are some warnings.

Since @vue/cli-plugin-eslint uses eslint's CLIEngine instead of the cli object, this option is not supported (it is handled by cli.js, not cli-engine.js). It would be nice to have this feature in vue cli, either by re-implementing it, or by using the cli.js script of eslint.

What does the proposed API look like?

vue-cli-service lint --max-warnings=0