Consolidate rust_prost_library and fix extension-only proto generation. (bazelbuild#2047)

This PR consolidates rust_prost_library and rust_tonic_library into one rule; `rust_prost_library`. `rust_prost_library` will generate tonic services if you provide a `tonic_plugin` in the toolchain definition. If you do not provide that plugin and you try to build a proto with services, it will print a warning that you should add a `tonic_plugin`.

This PR also handles extension-only proto files. Prost does not generate a file if there are no messages, enums, or services and it appears that Prost doesn't even support proto2 extensions. So to work around this issue, protoc_wrapper will generate an empty `.rs` file in the case that there are only extensions defined in a file.

Closes: bazelbuild#2046

Author: freeformstu

WORKSPACE.bazel

@@ -52,6 +52,10 @@ load("//test:deps.bzl", "rules_rust_test_deps")
 
 rules_rust_test_deps()
 
+load("//test:deps_transitive.bzl", "rules_rust_test_deps_transitive")
+
+rules_rust_test_deps_transitive()
+
 # --- end stardoc
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

docs/BUILD.bazel

@@ -122,7 +122,6 @@ PAGES = dict([
             "rust_proto_transitive_repositories",
             "rust_proto_toolchain",
             "rust_prost_library",
-            "rust_tonic_library",
         ],
     ),
     page(

docs/flatten.md

@@ -44,7 +44,6 @@
 * [rust_stdlib_filegroup](#rust_stdlib_filegroup)
 * [rust_test](#rust_test)
 * [rust_test_suite](#rust_test_suite)
-* [rust_tonic_library](#rust_tonic_library)
 * [rust_toolchain](#rust_toolchain)
 * [rust_toolchain_repository](#rust_toolchain_repository)
 * [rust_toolchain_repository_proxy](#rust_toolchain_repository_proxy)
@@ -2019,25 +2018,6 @@ rust_test_suite(
 | <a id="rust_test_suite-kwargs"></a>kwargs |  Additional keyword arguments for the underyling [rust_test](#rust_test) targets. The <code>tags</code> argument is also passed to the generated <code>test_suite</code> target.   |  none |
 
 
-<a id="rust_tonic_library"></a>
-
-## rust_tonic_library
-
-<pre>
-rust_tonic_library(<a href="#rust_tonic_library-name">name</a>, <a href="#rust_tonic_library-kwargs">kwargs</a>)
-</pre>
-
-A rule for generating a Rust library using Prost and Tonic.
-
-**PARAMETERS**
-
-
-| Name  | Description | Default Value |
-| :------------- | :------------- | :------------- |
-| <a id="rust_tonic_library-name"></a>name |  The name of the target.   |  none |
-| <a id="rust_tonic_library-kwargs"></a>kwargs |  Additional keyword arguments for the underlying <code>rust_tonic_library</code> rule.   |  none |
-
-
 <a id="rust_toolchain_repository"></a>
 
 ## rust_toolchain_repository

docs/rust_proto.md

@@ -7,16 +7,14 @@
 * [rust_proto_transitive_repositories](#rust_proto_transitive_repositories)
 * [rust_proto_toolchain](#rust_proto_toolchain)
 * [rust_prost_library](#rust_prost_library)
-* [rust_tonic_library](#rust_tonic_library)
 
 
 ## Overview
 These build rules are used for building [protobufs][protobuf]/[gRPC][grpc] in [Rust][rust] with Bazel.
 
 There are two rule sets. The first ruleset defines the `rust_proto_library` and `rust_grpc_library`
 rules which generate Rust code using the [`rust-protobuf`] dependencies. The second ruleset defines
-the `rust_prost_library` and `rust_tonic_library` rules which generate Rust code using the [`prost`]
-and [`tonic`] dependencies respectively.
+the `rust_prost_library` which generates Rust code using the [`prost`] and [`tonic`] dependencies.
 
 [rust]: http://www.rust-lang.org/
 [protobuf]: https://developers.google.com/protocol-buffers/
@@ -427,22 +425,3 @@ This macro should be called immediately after the `rust_proto_repositories` macr
 
 
 
-<a id="rust_tonic_library"></a>
-
-## rust_tonic_library
-
-<pre>
-rust_tonic_library(<a href="#rust_tonic_library-name">name</a>, <a href="#rust_tonic_library-kwargs">kwargs</a>)
-</pre>
-
-A rule for generating a Rust library using Prost and Tonic.
-
-**PARAMETERS**
-
-
-| Name  | Description | Default Value |
-| :------------- | :------------- | :------------- |
-| <a id="rust_tonic_library-name"></a>name |  The name of the target.   |  none |
-| <a id="rust_tonic_library-kwargs"></a>kwargs |  Additional keyword arguments for the underlying <code>rust_tonic_library</code> rule.   |  none |
-
-

docs/rust_proto.vm

@@ -4,8 +4,7 @@ These build rules are used for building [protobufs][protobuf]/[gRPC][grpc] in [R
 
 There are two rule sets. The first ruleset defines the `rust_proto_library` and `rust_grpc_library`
 rules which generate Rust code using the [`rust-protobuf`] dependencies. The second ruleset defines
-the `rust_prost_library` and `rust_tonic_library` rules which generate Rust code using the [`prost`]
-and [`tonic`] dependencies respectively.
+the `rust_prost_library` which generates Rust code using the [`prost`] and [`tonic`] dependencies.
 
 [rust]: http://www.rust-lang.org/
 [protobuf]: https://developers.google.com/protocol-buffers/

docs/symbols.bzl

@@ -32,7 +32,6 @@ load(
     _rust_grpc_library = "rust_grpc_library",
     _rust_prost_library = "rust_prost_library",
     _rust_proto_library = "rust_proto_library",
-    _rust_tonic_library = "rust_tonic_library",
 )
 load(
     "@rules_rust//proto:repositories.bzl",
@@ -127,7 +126,6 @@ rust_doc_test = _rust_doc_test
 rust_proto_library = _rust_proto_library
 rust_grpc_library = _rust_grpc_library
 rust_prost_library = _rust_prost_library
-rust_tonic_library = _rust_tonic_library
 
 rust_bindgen = _rust_bindgen
 rust_bindgen_dependencies = _rust_bindgen_dependencies

proto/defs.bzl

@@ -3,7 +3,6 @@
 load(
     "//proto/prost:defs.bzl",
     _rust_prost_library = "rust_prost_library",
-    _rust_tonic_library = "rust_tonic_library",
 )
 load(
     ":proto.bzl",
@@ -15,4 +14,3 @@ rust_proto_library = _rust_proto_library
 rust_grpc_library = _rust_grpc_library
 
 rust_prost_library = _rust_prost_library
-rust_tonic_library = _rust_tonic_library

proto/prost/defs.bzl

@@ -4,7 +4,6 @@ load(
     "//proto/prost/private:prost.bzl",
     _rust_prost_library = "rust_prost_library",
     _rust_prost_toolchain = "rust_prost_toolchain",
-    _rust_tonic_library = "rust_tonic_library",
 )
 
 def rust_prost_library(name, **kwargs):
@@ -30,27 +29,4 @@ def rust_prost_library(name, **kwargs):
         **kwargs
     )
 
-def rust_tonic_library(name, **kwargs):
-    """A rule for generating a Rust library using Prost and Tonic.
-
-    Args:
-        name (str): The name of the target.
-        **kwargs (dict): Additional keyword arguments for the underlying
-            `rust_tonic_library` rule.
-    """
-
-    # Clippy and Rustfmt will attempt to run on these targets.
-    # This is not correct and likely a bug in target detection.
-    tags = kwargs.pop("tags", [])
-    if "no-clippy" not in tags:
-        tags.append("no-clippy")
-    if "no-rustfmt" not in tags:
-        tags.append("no-rustfmt")
-
-    _rust_tonic_library(
-        name = name,
-        tags = tags,
-        **kwargs
-    )
-
 rust_prost_toolchain = _rust_prost_toolchain