Add bazel targets for standalone plugin binaries (#23919)

Follow-up to #23736 and #13308 but with only Bazel targets added per feedback.

This PR adds targets to build protoc plugins for all the built-in plugins. This will result in the following binaries being available:

- protoc-gen-cpp
- protoc-gen-csharp
- protoc-gen-java
- protoc-gen-kotlin
- protoc-gen-objectivec
- protoc-gen-php
- protoc-gen-python
- protoc-gen-pyi
- protoc-gen-ruby
- protoc-gen-rust

Closes #23919

COPYBARA_INTEGRATE_REVIEW=#23919 from bufdev:standalone-plugins 45d44f6
PiperOrigin-RevId: 917373434

Author: bufdev

src/google/protobuf/compiler/cpp/BUILD.bazel

@@ -10,8 +10,8 @@ load("//build_defs:cpp_opts.bzl", "COPTS")
 
 cc_binary(
     name = "protoc-gen-cpp",
-    srcs = ["main.cc"],
-    visibility = ["//:__pkg__"],
+    srcs = ["plugin_main.cc"],
+    visibility = ["//visibility:public"],
     deps = [
         ":cpp",
         "//src/google/protobuf/compiler:plugin",

src/google/protobuf/compiler/cpp/main.cc …gle/protobuf/compiler/cpp/plugin_main.ccsrc/google/protobuf/compiler/cpp/main.cc renamed to src/google/protobuf/compiler/cpp/plugin_main.cc src/google/protobuf/compiler/cpp/main.cc renamed to src/google/protobuf/compiler/cpp/plugin_main.cc

@@ -2,10 +2,21 @@
 # Protocol Buffers Compiler - C# code generator
 ################################################################################
 
+load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
 load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
 load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
 load("//build_defs:cpp_opts.bzl", "COPTS")
 
+cc_binary(
+    name = "protoc-gen-csharp",
+    srcs = ["plugin_main.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":csharp",
+        "//src/google/protobuf/compiler:plugin",
+    ],
+)
+
 cc_library(
     name = "names",
     srcs = ["names.cc"],

src/google/protobuf/compiler/csharp/BUILD.bazel

@@ -0,0 +1,14 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#include "google/protobuf/compiler/csharp/csharp_generator.h"
+#include "google/protobuf/compiler/plugin.h"
+
+int main(int argc, char* argv[]) {
+  google::protobuf::compiler::csharp::Generator generator;
+  return google::protobuf::compiler::PluginMain(argc, argv, &generator);
+}

src/google/protobuf/compiler/csharp/plugin_main.cc

@@ -2,6 +2,7 @@
 # Protocol Buffers Compiler - Java code generator
 ################################################################################
 
+load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
 load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
 load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
 load("//build_defs:cpp_opts.bzl", "COPTS")
@@ -12,6 +13,16 @@ package(
     ],
 )
 
+cc_binary(
+    name = "protoc-gen-java",
+    srcs = ["plugin_main.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":java",
+        "//src/google/protobuf/compiler:plugin",
+    ],
+)
+
 cc_library(
     name = "names",
     hdrs = ["names.h"],

src/google/protobuf/compiler/java/BUILD.bazel

@@ -1,6 +1,17 @@
+load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
 load("@rules_cc//cc:cc_library.bzl", "cc_library")
 load("//build_defs:cpp_opts.bzl", "COPTS")
 
+cc_binary(
+    name = "protoc-gen-kotlin",
+    srcs = ["plugin_main.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":kotlin",
+        "//src/google/protobuf/compiler:plugin",
+    ],
+)
+
 cc_library(
     name = "kotlin",
     srcs = ["generator.cc"],

src/google/protobuf/compiler/kotlin/BUILD.bazel

@@ -0,0 +1,14 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#include "google/protobuf/compiler/kotlin/generator.h"
+#include "google/protobuf/compiler/plugin.h"
+
+int main(int argc, char* argv[]) {
+  google::protobuf::compiler::kotlin::KotlinGenerator generator;
+  return google::protobuf::compiler::PluginMain(argc, argv, &generator);
+}

src/google/protobuf/compiler/kotlin/plugin_main.cc

@@ -2,10 +2,21 @@
 # Protocol Buffers Compiler - ObjC code generator
 ################################################################################
 
+load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
 load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
 load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
 load("//build_defs:cpp_opts.bzl", "COPTS")
 
+cc_binary(
+    name = "protoc-gen-objectivec",
+    srcs = ["plugin_main.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":objectivec",
+        "//src/google/protobuf/compiler:plugin",
+    ],
+)
+
 cc_library(
     name = "names",
     hdrs = ["names.h"],

src/google/protobuf/compiler/objectivec/BUILD.bazel

@@ -0,0 +1,14 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#include "google/protobuf/compiler/objectivec/generator.h"
+#include "google/protobuf/compiler/plugin.h"
+
+int main(int argc, char* argv[]) {
+  google::protobuf::compiler::objectivec::ObjectiveCGenerator generator;
+  return google::protobuf::compiler::PluginMain(argc, argv, &generator);
+}

src/google/protobuf/compiler/objectivec/plugin_main.cc

@@ -7,11 +7,22 @@
 
 # Public targets for PHP code generator.
 
+load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
 load("@rules_cc//cc:cc_test.bzl", "cc_test")
 load("@rules_cc//cc:defs.bzl", "cc_library")
 load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
 load("//build_defs:cpp_opts.bzl", "COPTS")
 
+cc_binary(
+    name = "protoc-gen-php",
+    srcs = ["plugin_main.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":php_generator",
+        "//src/google/protobuf/compiler:plugin",
+    ],
+)
+
 cc_library(
     name = "names",
     srcs = ["names.cc"],