gRPC Java compiler isn't using fully qualified names for String

[pkwarren]

What version of gRPC-Java are you using?

v1.56.0

What is your environment?

Linux, Java 17

What did you expect to see?

Generated code from the gRPC Java compiler should use fully qualified names for String.

What did you see instead?

Compilation error for inputs that include a message type named String.

Steps to reproduce the bug

syntax = "proto3";

package example;

message String {
  string val = 1;
}

message GetThingRequest {
  string id = 1;
}

message GetThingResponse {
  String id = 1;
}

service ExampleService {
  rpc GetThing(GetThingRequest) returns (GetThingResponse);
}

To generate code, I'm using buf with this buf.gen.yaml:

version: v1
managed:
  enabled: true
plugins:
- plugin: buf.build/protocolbuffers/java
  out: gen
- plugin: buf.build/grpc/java
  out: gen

The issue seems to be that the variable here

grpc-java/compiler/src/java_plugin/cpp/java_generator.cpp

Line 1224 in f3399e3

vars["String"] = "java.lang.String";

isn't being used at the following locations:

• grpc-java/compiler/src/java_plugin/cpp/java_generator.cpp

  Line 992 in f3399e3

  " private final String methodName;\n"

• grpc-java/compiler/src/java_plugin/cpp/java_generator.cpp

  Line 994 in f3399e3

  " $proto_method_descriptor_supplier$(String methodName) {\n"

• grpc-java/compiler/src/java_plugin/cpp/java_generator.cpp

  Line 1152 in f3399e3

  "public static final String SERVICE_NAME = "

I'm happy to raise a PR to fix but I'm having a hard time getting the local build to work end to end on MacOS arm64 and Linux arm64. I imagine this will require not only changing the compiler but also potentially updating tests and regenerating code with the new compiler.

[pkwarren]

Opened related issue #10317 for updating the compilation docs to work with newer protoc versions.

[ejona86]

Yeah, we need to use the fully-qualified String. I know it is annoying for us Java developers to need to build C++, but let's see if that gets working in #10317.