protos does not have mandatory providers: 'PyInfo' or 'CcInfo'.

[gfrankliu]

We recently upgraded the bazel module versions in MODULE.bazel, including rules_python to the latest 1.4.1. Now bazel build of py_library target which has a dep of proto fails with the error that the protos don't have mandatory providers: 'PyInfo' or 'CcInfo'. Everything works fine before the upgrade.

If I move the protos from "deps" to "srcs", the py_library build will succeed.

I compared my BUILD file with this example and find I don't explicitly load py_library. I then added load("@rules_python//python:defs.bzl", "py_library" to my BUILD, then the error about not have mandatory providers: 'PyInfo' or 'CcInfo' goes away. Is this "load" line mandatory now? I am using bazel 7.4.1 if that matters.

[rickeylev]

Yes, explicitly loading the python rules is mandatory. The python rules have been removed from Bazel as of Bazel 9.

There's some basic compatibility code in rules_python to try and make interactions between the two implementations mostly work. The best way forward is to add load statements so there's just one implementation used.

move from deps to src

This might work incidentally or in this particular case, but is prone to problems. What happens is targets in srcs are treated as regular files (as if a filegroup was being used). The transitive metadata (from PyInfo) from deps and transitive deps will be lost. Whether that metadata is critical or not depends on the details.