When trying it all out, --//:myflag=foo works, but --@rules_my_language//:myflag=foo does not. I've tried to make an alias and then go for the first alternative, but that fails as well with ERROR: Unrecognized option: //:myflag.

Is it a design choice to not allow command line flags from external dependencies? Is a bug so I should file a bug report? Is it a feature request to allow it in v2, possibly via the WORKSPACE file?

Originally posted by @moroten in #5577 (comment)