Use a new prost ServiceGenerator finalizer to fix duplicate client and server definitions

[parasyte]

Note: This PR is in draft mode until the dependent PR in prost is accepted and released: https://github.com/danburkert/prost/pull/241

Motivation

Fixes #38

This change allows tonic-build to properly group all services from multiple .proto files into a single package namespace.

Solution

Defer code generation to the end of all package processing.

[parasyte]

Ah jeez, failures in cargo-deny and tests that I didn't touch at all... Maybe these will get sorted in master in the meantime and this PR will be fixed by merge or rebase! 😉

[parasyte]

I'm not happy with the new requirement that user code has to include all packages explicitly. Go doesn't have this problem because it will happily pull all packages into scope from a single import directive.

I don't see an obvious way to auto-include packages within the generated source. The conflict is that imports in protobuf are "file level" and includes in tonic-build are "package level".

[parasyte]

I see, this is actually a bug! The client and server modules are being output to the wrong package. I will be addressing this tomorrow.

[alce]

@parasyte the cargo-deny check is failing in part because of a duplicated version of crossbeam-queue, which is addressed here #145 and in part because you are referencing a different version of prost-build.

We'll need #145 to be merged first, or at least the commits that fix the crossbeam duplication and then fix the prost-build issue here

[parasyte]

Ok, we're good here. All tests are passing, just waiting for prost-build 0.5.1 and @alce's crossbeam-queue patch for the cargo deny checks to pass.

[jen20]

@parasyte I'll look at resolving the issue with cargo-deny shortly, it's affected quite a few of our open PRs right now.

[LucioFranco]

This looks good! Once prost gets a publish out we can merge this! Thanks!

[parasyte]

That sounds great. I'll keep the PR as a draft until I can update Cargo.toml with whatever prost version gets released.

[parasyte]

Looks like #173 fixes this by namespacing the client/server modules separately.

[LucioFranco]

@parasyte yup, thank you for this contribution sorry we couldn't get it in, but also looks like prost is a bit slow on upgrading anyways. I am gonna close this as it seems its been solved for you!

[parasyte]

I haven't actually used the new code yet, but I am interested in trying it.