One thing we see come up a lot is needing to pass options that we pass to our build differently for the host configuration. In some cases bazel has a flag for this like --host_swiftcopt / --swiftcopt etc. In other cases, for whatever reason, bazel does not yet have a flag for the use case, such as #13001 or --host_features and how --features applies everywhere.

I think it would be useful for there to be a generic --host_opt flag with syntax such as --host_opt=--normal_opt=value that allowed you to pass through arbitrary bazel options to the host configuration.

This opens the door for much more API usage for the host configuration, but I think that could be preferred to the trade off of trying to add a host flag for ever applicable option.