Ivo List

Please report the issue on rules_apple. cc @keith

> > This PR should be applied during the release: after archives with prebuilt binaries are created (so that we can compute checksums), but before the source archive is created....

> While I like the direction, what's the reason for not registering a toolchain per OS/architecture with --incompatible_enable_proto_toolchain_resolution plus the existing source-based toolchain last? The registered toolchain points to //:protoc,...

> @comius - can you update this PR to resolve the merge conflicts? Done. (I rebased to 30.x)

@JasonLunn I can fix the failures - but perhaps you missed the point, that this PR is intended to demonstrate how to use prebuilt binaries and even with fixed failures,...

Hey all, I've got an idea over a lunch break, how to implement this, without modifying protobuf release procedures. It wouldn't be hard to implement at all. The only caveat...

Wow, this is one nice PR. It's a shame it's here for 1.5 years.

@c-mita please triage