Can I use a different version of protobuf to Bazel's?

[tmewett]

Hi, I want to depend on a specific version of protobuf:

bazel_dep(name = "protobuf", version = "27.0")

but Bazel is telling me that it's using a fixed version instead (v29):

WARNING: For repository 'protobuf', the root module requires module version [email protected], but got [email protected] in the resolved dependency graph. Please update the version in your MODULE.bazel or set --check_direct_dependencies=off

My investigations have led me to believe this is because the built-in Bazel module bazel_tools depends on protobuf v29, as seen in the built-in MODULE.tools: https://github.com/bazelbuild/bazel/blob/release-8.4.2/src/MODULE.tools

Have I got the wrong idea here? Or am I forced to use the same version of protobuf as Bazel uses? Things I've tried:

• single_version_override: it causes an internal Bazel error (it seems the Bazel source code hard-depends on something in v29 - I think it's to do with this commit: Move ProtoInfo and ProtoLangToolchainInfo from Bazel · protocolbuffers/protobuf@426ca8a)
• multiple_version_override: has no effect
• upgrading to Bazel 9: had the same problem, this time internally depending on protobuf v33 instead of v29

Any help appreciated

[meteorcloudy]

Yes, older protobuf version won't be compatible with recent Bazel versions due to some breaking changes. multiple_version_override should be able to allow multiple protobuf version to co-exist, but you'll have to be very careful to not introduce conflict dependency.