Per bpo-41263, code.__new__ now uses Argument Clinic. However, it still has a / marker which prevents the use of keyword arguments (https://github.com/python/cpython/pull/21426/files#diff-6f869eb8beb7cbe4bc6817584b99ad567f88962fa67f7beca25d009dc401234dR465).

It seems entirely unnecessary to have this, so could it be removed to allow easier construction of code objects from user code, or is it there for some specific reason?

I can do a PR - it's a 1 line change (+ clinic output changes) (+ tests?).

I don't imagine backwards-compatibility is a concern here given it's implementation-specific and basically private.

Note that prior to that fix, keyword arguments were allowed in the constructor but completely ignored.

Generally, construction time is faster if the arguments are positional only.  

Also, this isn't a method that people typically call directly — it is only quasi-public because the layout of the codestring is implementation dependent and changes every now and then.   Given that it is essentially private, there is no benefit to exposing keyword argument calls.

Thanks for the suggestion, but I don't think it makes things better for users.