fix(build): Remove ambiguity in service method call (#327)

When calling methods on Arc<MyService> where the method is also defined on Arc (e.g. drop and clone), calling inner.#method_ident(request) will actually attempt to call the Arc method instead of the method on the service, resulting in a compile error. This change removes the ambiguity by dereferencing the inner Arc.

Cargo.toml

@@ -13,5 +13,6 @@ members = [
     "tests/same_name",
     "tests/wellknown",
     "tests/extern_path/uuid",
+    "tests/ambiguous_methods",
     "tests/extern_path/my_application"
 ]

tests/ambiguous_methods/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "ambiguous_methods"
+version = "0.1.0"
+authors = ["Yonathan Randolph <yonathan@gmail.com>"]
+edition = "2018"
+publish = false
+license = "MIT"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+tonic = { path= "../../tonic" }
+prost = "0.6"
+
+[build-dependencies]
+tonic-build = { path= "../../tonic-build" }

tests/ambiguous_methods/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    tonic_build::compile_protos("proto/ambiguous_methods.proto").unwrap();
+}

tests/ambiguous_methods/proto/ambiguous_methods.proto

@@ -0,0 +1,19 @@
+syntax = "proto3";
+
+package ambiguous_methods;
+
+message DropReq {}
+message DropResp {}
+
+// The generated stubs can confuse drop and clone
+// with the same method names from Arc,
+// resulting in a compile error.
+service HelloService {
+    rpc Drop (DropReq) returns (DropResp);
+    rpc Clone (DropReq) returns (DropResp);
+}
+
+service HelloStreamingService {
+    rpc Drop (DropReq) returns (stream DropResp);
+    rpc Clone (DropReq) returns (stream DropResp);
+}

tests/ambiguous_methods/src/main.rs

@@ -0,0 +1,8 @@
+#[macro_use]
+extern crate tonic;
+
+tonic::include_proto!("ambiguous_methods");
+
+fn main() {
+    println!("Hello, world!");
+}

tonic-build/src/server.rs

@@ -273,7 +273,7 @@ fn generate_unary<T: Method>(
             fn call(&mut self, request: tonic::Request<#request>) -> Self::Future {
                 let inner = self.0.clone();
                 let fut = async move {
-                    inner.#method_ident(request).await
+                    (*inner).#method_ident(request).await
                 };
                 Box::pin(fut)
             }
@@ -326,7 +326,7 @@ fn generate_server_streaming<T: Method>(
             fn call(&mut self, request: tonic::Request<#request>) -> Self::Future {
                 let inner = self.0.clone();
                 let fut = async move {
-                    inner.#method_ident(request).await
+                    (*inner).#method_ident(request).await
 
                 };
                 Box::pin(fut)
@@ -377,7 +377,7 @@ fn generate_client_streaming<T: Method>(
             fn call(&mut self, request: tonic::Request<tonic::Streaming<#request>>) -> Self::Future {
                 let inner = self.0.clone();
                 let fut = async move {
-                    inner.#method_ident(request).await
+                    (*inner).#method_ident(request).await
 
                 };
                 Box::pin(fut)
@@ -432,7 +432,7 @@ fn generate_streaming<T: Method>(
             fn call(&mut self, request: tonic::Request<tonic::Streaming<#request>>) -> Self::Future {
                 let inner = self.0.clone();
                 let fut = async move {
-                    inner.#method_ident(request).await
+                    (*inner).#method_ident(request).await
                 };
                 Box::pin(fut)
             }