From cc84beeb7e4091de35e487ba2849c53f37290217 Mon Sep 17 00:00:00 2001
From: Tuetuopay <tuetuopay@me.com>
Date: Sat, 26 Mar 2022 16:42:30 +0100
Subject: [PATCH 1/2] Expose Prost generation plugin

Exposing such plugin allows independent code generators (outside of the
vanilla `build.rs` workflow) to use tonic-build to get gRPC code
generation. This paves the way for a `protoc-gen-tonic` plugin, opening
integration in e.g. buf.
---
 tonic-build/src/lib.rs   |  2 +-
 tonic-build/src/prost.rs | 12 ++++++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/tonic-build/src/lib.rs b/tonic-build/src/lib.rs
index 385051419..beb032f57 100644
--- a/tonic-build/src/lib.rs
+++ b/tonic-build/src/lib.rs
@@ -77,7 +77,7 @@ mod prost;
 
 #[cfg(feature = "prost")]
 #[cfg_attr(docsrs, doc(cfg(feature = "prost")))]
-pub use prost::{compile_protos, configure, Builder};
+pub use prost::{compile_protos, configure, Builder, ServiceGenerator};
 
 /// Service code generation for client
 pub mod client;
diff --git a/tonic-build/src/prost.rs b/tonic-build/src/prost.rs
index d5a1b2789..78300a959 100644
--- a/tonic-build/src/prost.rs
+++ b/tonic-build/src/prost.rs
@@ -133,14 +133,22 @@ fn is_google_type(ty: &str) -> bool {
     ty.starts_with(".google.protobuf")
 }
 
-struct ServiceGenerator {
+/// A service generator compatible with `prost_build`'s one, to extend its code generator.
+///
+/// This is used internally by Tonic build, but also when the codegen output is not to be handled
+/// by prost or tonic; e.g. such as in a flow for a `protoc` code generation plugin. When compiling
+/// as part of a `build.rs` file, instead use [`compile_protos()`].
+#[derive(Debug)]
+pub struct ServiceGenerator {
     builder: Builder,
     clients: TokenStream,
     servers: TokenStream,
 }
 
 impl ServiceGenerator {
-    fn new(builder: Builder) -> Self {
+    /// Create a new service generator from a configured builder, ready to be passed to
+    /// `prost_build`'s `Config::service_generator`.
+    pub fn new(builder: Builder) -> Self {
         ServiceGenerator {
             builder,
             clients: TokenStream::default(),

From afb68eba54500d5d86bd46d6f531904c789270b0 Mon Sep 17 00:00:00 2001
From: Tuetuopay <tuetuopay@me.com>
Date: Thu, 31 Mar 2022 10:25:51 +0200
Subject: [PATCH 2/2] build: Replace the pub service generator struct with a
 getter

This simplifies the code as it allows to simply write
`configure() /* opts */ .service_generator()`.
---
 tonic-build/src/lib.rs   |  2 +-
 tonic-build/src/prost.rs | 20 +++++++++-----------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/tonic-build/src/lib.rs b/tonic-build/src/lib.rs
index beb032f57..385051419 100644
--- a/tonic-build/src/lib.rs
+++ b/tonic-build/src/lib.rs
@@ -77,7 +77,7 @@ mod prost;
 
 #[cfg(feature = "prost")]
 #[cfg_attr(docsrs, doc(cfg(feature = "prost")))]
-pub use prost::{compile_protos, configure, Builder, ServiceGenerator};
+pub use prost::{compile_protos, configure, Builder};
 
 /// Service code generation for client
 pub mod client;
diff --git a/tonic-build/src/prost.rs b/tonic-build/src/prost.rs
index 78300a959..303f1c2df 100644
--- a/tonic-build/src/prost.rs
+++ b/tonic-build/src/prost.rs
@@ -133,22 +133,14 @@ fn is_google_type(ty: &str) -> bool {
     ty.starts_with(".google.protobuf")
 }
 
-/// A service generator compatible with `prost_build`'s one, to extend its code generator.
-///
-/// This is used internally by Tonic build, but also when the codegen output is not to be handled
-/// by prost or tonic; e.g. such as in a flow for a `protoc` code generation plugin. When compiling
-/// as part of a `build.rs` file, instead use [`compile_protos()`].
-#[derive(Debug)]
-pub struct ServiceGenerator {
+struct ServiceGenerator {
     builder: Builder,
     clients: TokenStream,
     servers: TokenStream,
 }
 
 impl ServiceGenerator {
-    /// Create a new service generator from a configured builder, ready to be passed to
-    /// `prost_build`'s `Config::service_generator`.
-    pub fn new(builder: Builder) -> Self {
+    fn new(builder: Builder) -> Self {
         ServiceGenerator {
             builder,
             clients: TokenStream::default(),
@@ -420,10 +412,16 @@ impl Builder {
             config.protoc_arg(arg);
         }
 
-        config.service_generator(Box::new(ServiceGenerator::new(self)));
+        config.service_generator(self.service_generator());
 
         config.compile_protos(protos, includes)?;
 
         Ok(())
     }
+
+    /// Turn the builder into a `ServiceGenerator` ready to be passed to `prost-build`s
+    /// `Config::service_generator`.
+    pub fn service_generator(self) -> Box<dyn prost_build::ServiceGenerator> {
+        Box::new(ServiceGenerator::new(self))
+    }
 }