Fail when expected files are not produced by protoc

[linzhp]

What type of PR is this?
Bug fix

What does this PR do? Why is it needed?
This PR fail the action if a plugin does not produce a valid Go file that it is supposed to produce. This disallows people to add gRPC plugin to a go_proto_library target that has no service definition, but avoids the cache poisoning due to bugs in proto plugins. Because Gazelle is able to switch between proto and grpc plugins depending on the existence of service definition, existing repos managed by Gazelle will not be affected.

Which issues(s) does this PR fix?

Fixes #3949

Other notes for review
Credits to @r-hang for coming up with the patch

[sluongng]

This is a bit too strict.

We have several use cases where a proto_library target would contain both message and service proto files inside srcs attribute. Then the go_proto_library target would wrap that proto_library target with both the regular compiler and the grpc compiler.

https://github.com/buildbuddy-io/buildbuddy/blob/87810234ab7ec1be168288d078a0d718d8e6ff25/proto/api/v1/BUILD#L36-L70

OR, a gazelle-generated BUILD like this in one of our dependencies

load("@io_bazel_rules_go//go:def.bzl", "go_library")
load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
load("@rules_proto//proto:defs.bzl", "proto_library")

proto_library(
    name = "apis_proto",
    srcs = [
        "classification.proto",
        "get_model_metadata.proto",
        "inference.proto",
        "input.proto",
        "model.proto",
        "predict.proto",
        "prediction_service.proto", # service proto
        "regression.proto",
    ],
    visibility = ["//visibility:public"],
    deps = [
        "//tensorflow/core/example:example_proto",
        "//tensorflow/core/framework:framework_proto",
        "//tensorflow/core/protobuf:protobuf_proto",
        "@com_google_protobuf//:any_proto",
        "@com_google_protobuf//:wrappers_proto",
    ],
)

go_proto_library(
    name = "apis_go_proto",
    compilers = ["@io_bazel_rules_go//proto:go_grpc_v2"],
    importpath = "github.com/buildbuddy-io/tensorflow-proto/tensorflow_serving/apis",
    proto = ":apis_proto",
    visibility = ["//visibility:public"],
    deps = [
        "//tensorflow/core/example",
        "//tensorflow/core/framework",
        "//tensorflow/core/protobuf",
    ],
)

go_library(
    name = "apis",
    embed = [":apis_go_proto"],
    importpath = "github.com/buildbuddy-io/tensorflow-proto/tensorflow_serving/apis",
    visibility = ["//visibility:public"],
)

alias(
    name = "go_default_library",
    actual = ":apis",
    visibility = ["//visibility:public"],
)

[Moersity]

This is a bit too strict.

We have several use cases where a proto_library target would contain both message and service proto files inside srcs attribute. Then the go_proto_library target would wrap that proto_library target with both the regular compiler and the grpc compiler.

https://github.com/buildbuddy-io/buildbuddy/blob/87810234ab7ec1be168288d078a0d718d8e6ff25/proto/api/v1/BUILD#L36-L70

OR, a gazelle-generated BUILD like this in one of our dependencies

load("@io_bazel_rules_go//go:def.bzl", "go_library")
load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
load("@rules_proto//proto:defs.bzl", "proto_library")

proto_library(
    name = "apis_proto",
    srcs = [
        "classification.proto",
        "get_model_metadata.proto",
        "inference.proto",
        "input.proto",
        "model.proto",
        "predict.proto",
        "prediction_service.proto", # service proto
        "regression.proto",
    ],
    visibility = ["//visibility:public"],
    deps = [
        "//tensorflow/core/example:example_proto",
        "//tensorflow/core/framework:framework_proto",
        "//tensorflow/core/protobuf:protobuf_proto",
        "@com_google_protobuf//:any_proto",
        "@com_google_protobuf//:wrappers_proto",
    ],
)

go_proto_library(
    name = "apis_go_proto",
    compilers = ["@io_bazel_rules_go//proto:go_grpc_v2"],
    importpath = "github.com/buildbuddy-io/tensorflow-proto/tensorflow_serving/apis",
    proto = ":apis_proto",
    visibility = ["//visibility:public"],
    deps = [
        "//tensorflow/core/example",
        "//tensorflow/core/framework",
        "//tensorflow/core/protobuf",
    ],
)

go_library(
    name = "apis",
    embed = [":apis_go_proto"],
    importpath = "github.com/buildbuddy-io/tensorflow-proto/tensorflow_serving/apis",
    visibility = ["//visibility:public"],
)

alias(
    name = "go_default_library",
    actual = ":apis",
    visibility = ["//visibility:public"],
)

We encountered the same problem, so what should we do now? downgrage rules_go version seem likes a bad idea

[linzhp]

We should revert this PR