Added proto_compile_deps and grpc_compile_deps to @io_bazel_rules_rust//proto:toolchain

[UebelAndre]

Closes #483

This PR adds proto_compile_deps and grpc_compile_deps to the @io_bazel_rules_rust//proto:toolchain toolchain to close a comment

# TODO(damienmg): Once bazelbuild/bazel#6889 is fixed, reintroduce
# proto_compile_deps and grpc_compile_deps and remove them from the
# rust_proto_library and grpc_proto_library.

This is doable now that bazelbuild/bazel#6889 is closed.

Though, I'm not entirely clear on what the earliest version of Bazel that supports this fix is. It looks like 3.4 as per bazelbuild/bazel@bc4ef8c from bazelbuild/bazel#10523

Unsure of what to do with these changes in that case.

[UebelAndre]

Oh, the CI failure is caused by missing changes from #518 @damienmg would you be able to take a look there and here?

[UebelAndre]

Yeah, I don't even think this will pass CI without updating the version of Bazel 😢

[damienmg]

@UebelAndre I don't understand, what missing change? CI seems to be green @Head.

[UebelAndre]

Oh, the CI failure is caused by missing changes from #518 @damienmg would you be able to take a look there and here?

@damienmg That's been resolved

There's a new failure, at least for Build #1722

[UebelAndre]

@UebelAndre I don't understand, what missing change? CI seems to be green @Head.

Oh, and I was referring to the fact that CI in this PR had failed and I didn't expect it to. The recent builds are passing except for the Minimum Supported Version test. This makes sense due to the addition of incompatible_use_toolchain_transition (as per bazelbuild/bazel#11584). This is what I was referring to when I was saying I don't think CI will pass since this functionality seems relatively new.

[UebelAndre]

I think the minimum supported version would have to go up to 3.4 for this based on this commit: bazelbuild/bazel@099cf2f

[UebelAndre]

This is blocked by #529

[UebelAndre]

Gonna close this for now. Doesn't seem there's any interest in this change and I don't have the bandwidth to drive it forward.

I'm dumping a diff below since the changes are relatively small and I'm not sure what happens to changes on a PR once it's closed and the original branch is deleted.

diff --git a/proto/proto.bzl b/proto/proto.bzl
index 00769f8..5ff2082 100644
--- a/proto/proto.bzl
+++ b/proto/proto.bzl
@@ -34,8 +34,6 @@ rust_proto_repositories()
 
 load(
     "@io_bazel_rules_rust//proto:toolchain.bzl",
-    "GRPC_COMPILE_DEPS",
-    "PROTO_COMPILE_DEPS",
     _generate_proto = "rust_generate_proto",
     _generated_file_stem = "generated_file_stem",
 )
@@ -209,6 +207,12 @@ def _rust_proto_compile(protos, descriptor_sets, imports, crate_name, ctx, is_gr
         output_hash,
     ))
 
+    # Gather all dependencies for compilation
+    compile_action_deps = depset(
+        compile_deps +
+        proto_toolchain.grpc_compile_deps if is_grpc else proto_toolchain.proto_compile_deps,
+    ).to_list()
+
     return rustc_compile_action(
         ctx = ctx,
         toolchain = find_toolchain(ctx),
@@ -217,7 +221,7 @@ def _rust_proto_compile(protos, descriptor_sets, imports, crate_name, ctx, is_gr
             type = "rlib",
             root = lib_rs,
             srcs = srcs,
-            deps = compile_deps,
+            deps = compile_action_deps,
             proc_macro_deps = [],
             aliases = {},
             output = rust_lib,
@@ -280,7 +284,6 @@ rust_proto_library = rule(
         ),
         "rust_deps": attr.label_list(
             doc = "The crates the generated library depends on.",
-            default = PROTO_COMPILE_DEPS,
         ),
         "_cc_toolchain": attr.label(
             default = "@bazel_tools//tools/cpp:current_cc_toolchain",
@@ -306,6 +309,9 @@ rust_proto_library = rule(
         "@io_bazel_rules_rust//rust:toolchain",
         "@bazel_tools//tools/cpp:toolchain_type",
     ],
+    # TODO: Remove once (bazelbuild/bazel#11584) is closed and the rules use
+    # the version of Bazel that issue was closed on as the min supported version
+    incompatible_use_toolchain_transition = True,
     doc = """\
 Builds a Rust library crate from a set of `proto_library`s.
 
@@ -359,7 +365,6 @@ rust_grpc_library = rule(
         ),
         "rust_deps": attr.label_list(
             doc = "The crates the generated library depends on.",
-            default = GRPC_COMPILE_DEPS,
         ),
         "_cc_toolchain": attr.label(
             default = "@bazel_tools//tools/cpp:current_cc_toolchain",
@@ -385,6 +390,9 @@ rust_grpc_library = rule(
         "@io_bazel_rules_rust//rust:toolchain",
         "@bazel_tools//tools/cpp:toolchain_type",
     ],
+    # TODO: Remove once (bazelbuild/bazel#11584) is closed and the rules use
+    # the version of Bazel that issue was closed on as the min supported version
+    incompatible_use_toolchain_transition = True,
     doc = """\
 Builds a Rust library crate from a set of `proto_library`s suitable for gRPC.
 
diff --git a/proto/toolchain.bzl b/proto/toolchain.bzl
index 67ccbe5..0f573ea 100644
--- a/proto/toolchain.bzl
+++ b/proto/toolchain.bzl
@@ -16,8 +16,21 @@
 
 load("@io_bazel_rules_rust//rust:private/rust.bzl", "name_to_crate_name")
 
-def generated_file_stem(f):
-    basename = f.rsplit("/", 2)[-1]
+def generated_file_stem(file_path):
+    """Returns the basename of a file without any extensions.
+
+    Example:
+    ```python
+    content.append("pub mod %s;" % _generated_file_stem(f))
+    ```
+
+    Args:
+        file_path (string): A path to a file
+
+    Returns:
+        string: The file stem of the filename
+    """
+    basename = file_path.rsplit("/", 2)[-1]
     basename = name_to_crate_name(basename)
     return basename.rsplit(".", 2)[0]
 
@@ -107,7 +120,9 @@ def _rust_proto_toolchain_impl(ctx):
     return platform_common.ToolchainInfo(
         protoc = ctx.executable.protoc,
         proto_plugin = ctx.file.proto_plugin,
+        proto_compile_deps = ctx.attr.proto_compile_deps,
         grpc_plugin = ctx.file.grpc_plugin,
+        grpc_compile_deps = ctx.attr.grpc_compile_deps,
         edition = ctx.attr.edition,
     )
 
@@ -123,9 +138,6 @@ GRPC_COMPILE_DEPS = PROTO_COMPILE_DEPS + [
     "@io_bazel_rules_rust//proto/raze:tls_api_stub",
 ]
 
-# TODO(damienmg): Once bazelbuild/bazel#6889 is fixed, reintroduce
-# proto_compile_deps and grpc_compile_deps and remove them from the
-# rust_proto_library and grpc_proto_library.
 rust_proto_toolchain = rule(
     implementation = _rust_proto_toolchain_impl,
     attrs = {
@@ -143,6 +155,11 @@ rust_proto_toolchain = rule(
                 "@io_bazel_rules_rust//proto:protoc_gen_rust",
             ),
         ),
+        "proto_compile_deps": attr.label_list(
+            doc = "The crates the generated protobuf libraries depends on.",
+            cfg = "target",
+            default = [Label(dep) for dep in PROTO_COMPILE_DEPS],
+        ),
         "grpc_plugin": attr.label(
             doc = "The location of the Rust protobuf compiler plugin to generate rust gRPC stubs.",
             allow_single_file = True,
@@ -151,6 +168,11 @@ rust_proto_toolchain = rule(
                 "@io_bazel_rules_rust//proto:protoc_gen_rust_grpc",
             ),
         ),
+        "grpc_compile_deps": attr.label_list(
+            doc = "The crates the generated grpc libraries depends on.",
+            cfg = "target",
+            default = [Label(dep) for dep in GRPC_COMPILE_DEPS],
+        ),
         "edition": attr.string(
             doc = "The edition used by the generated rust source.",
             default = "2015",