Fast cc proto support

* Changed some c++ direct module imports to not reference google internals
* Used pybind11_bazel config to provide python_headers lib
* open source protobuf build file is patched to give the
  library we need public visibility

PiperOrigin-RevId: 393445960

Author: Kevin Boyd

WORKSPACE

@@ -53,6 +53,7 @@ git_repository(
     name = "com_google_protobuf",
     remote = "https://github.com/protocolbuffers/protobuf.git",
     tag = "v3.18.0-rc1",
+    patches = ["com_google_protobuf_build.patch"],
 )
 
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
@@ -71,5 +72,5 @@ grpc_deps()
 
 bind(
     name = "python_headers",
-    actual = "@com_google_protobuf//util/python:python_headers",
+    actual = "@local_config_python//:python_headers",
 )

external/com_google_protobuf_build.patch

@@ -0,0 +1,11 @@
+--- BUILD
++++ BUILD
+@@ -889,6 +889,8 @@
+         "//conditions:default": [],
+         ":use_fast_cpp_protos": ["//external:python_headers"],
+     }),
++
++    visibility = ["//visibility:public"],
+ )
+ 
+ config_setting(

pybind11_protobuf/BUILD

@@ -70,6 +70,7 @@ pybind_library(
         "@com_google_absl//absl/strings",
         "@com_google_protobuf//:proto_api",
         "@com_google_protobuf//:protobuf",
+        "@com_google_protobuf//:python/google/protobuf/pyext/_message.so",  # fixdeps: keep
     ],
 )
 

pybind11_protobuf/proto_cast_util.cc

@@ -53,7 +53,7 @@ const GlobalState* GetGlobalState() {
 
       PyErr_Clear();
       try {
-        py::module_::import("google3.net.proto2.python.internal.cpp._message");
+        py::module_::import("google.protobuf.pyext._message");
       } catch (...) {
         // TODO(pybind11-infra): narrow down to expected exception(s).
         // Ignore any errors; they will appear immediately when the capsule
@@ -68,7 +68,7 @@ const GlobalState* GetGlobalState() {
       // When not using fast protos, we may construct protos from the default
       // pool.
       try {
-        auto m = py::module_::import("google3.net.proto2.python.public");
+        auto m = py::module_::import("google.protobuf");
         state->global_pool = m.attr("descriptor_pool").attr("Default")();
         state->factory = m.attr("message_factory")
                              .attr("MessageFactory")(state->global_pool);