I think it would be nice to have out-of-the-box support for the clang linter.

I think adding it in the Community Resources is a good move:

• It will let users use it right away
• You can collect feedback and fix stuff while it's there
• The wait time for upstreaming linters is very long (It's essentially a special integration, with all the costs of one). So getting it somewhere in the meanwhile makes sense.

clang-format-linter author here. I somehow missed the Community Resources page and yep ATM it's definitely a better place for this linter (alongside with one for Swift code).

BTW, what are requirements for linter to be upstreamed so I can keep them in mind?

Your Github repository is a nice reference. I will do the same for T9797

In T9870#146277, @vhbit wrote:

BTW, what are requirements for linter to be upstreamed so I can keep them in mind?

See https://secure.phabricator.com/book/phabcontrib/article/contributing_code/ and Q106; There's no hard-and-fast rule for this, but maintenance cost is very important.