Emit cargo:rerun-if-changed directives automatically for protobuf

Add a builder option to enable emitting `rerun-if-changed` cargo build
directives for all proto files. This removes the need to manually maintain
a list or proto files in build.rs.

base_layer/core/build.rs

@@ -29,6 +29,7 @@ fn main() {
             "src/base_node/proto",
             "src/transactions/transaction_protocol/proto",
         ])
+        .emit_rerun_if_changed_directives()
         .compile()
         .unwrap();
 }

base_layer/p2p/build.rs

@@ -24,8 +24,7 @@ fn main() {
     tari_common::protobuf_build::ProtoCompiler::new()
         .proto_paths(&["src/proto"])
         .out_dir("src/proto")
+        .emit_rerun_if_changed_directives()
         .compile()
         .unwrap();
-    println!("cargo:rerun-if-changed=src/proto/liveness.proto");
-    println!("cargo:rerun-if-changed=src/proto/message_type.proto");
 }

common/src/protobuf_build.rs

@@ -57,6 +57,7 @@ pub struct ProtoCompiler {
     field_attributes: HashMap<&'static str, &'static str>,
     proto_paths: Vec<PathBuf>,
     include_paths: Vec<PathBuf>,
+    emit_rerun_if_changed_directives: bool,
 }
 
 impl ProtoCompiler {
@@ -67,6 +68,7 @@ impl ProtoCompiler {
             field_attributes: HashMap::new(),
             proto_paths: Vec::new(),
             include_paths: Vec::new(),
+            emit_rerun_if_changed_directives: false,
         }
     }
 
@@ -92,6 +94,11 @@ impl ProtoCompiler {
         self
     }
 
+    pub fn emit_rerun_if_changed_directives(&mut self) -> &mut Self {
+        self.emit_rerun_if_changed_directives = true;
+        self
+    }
+
     pub fn include_paths<P: AsRef<Path>>(&mut self, include_paths: &[P]) -> &mut Self {
         self.include_paths
             .extend(include_paths.iter().map(|p| p.as_ref().to_path_buf()));
@@ -166,6 +173,12 @@ impl ProtoCompiler {
 
         fs::remove_dir_all(&tmp_out_dir).map_err(|err| format!("Failed to remove temporary dir: {}", err))?;
 
+        if self.emit_rerun_if_changed_directives {
+            for p in &protos {
+                println!("cargo:rerun-if-changed={}", p.to_string_lossy());
+            }
+        }
+
         Ok(())
     }
 }

comms/build.rs

@@ -24,6 +24,7 @@ fn main() {
     tari_common::protobuf_build::ProtoCompiler::new()
         .proto_paths(&["src/proto"])
         .out_dir("src/proto")
+        .emit_rerun_if_changed_directives()
         .compile()
         .unwrap();
 }

comms/dht/build.rs

@@ -24,10 +24,7 @@ fn main() {
     tari_common::protobuf_build::ProtoCompiler::new()
         .proto_paths(&["src/proto"])
         .out_dir("src/proto")
+        .emit_rerun_if_changed_directives()
         .compile()
         .unwrap();
-    println!("cargo:rerun-if-changed=src/proto/dht.proto");
-    println!("cargo:rerun-if-changed=src/proto/envelope.proto");
-    println!("cargo:rerun-if-changed=src/proto/message_header.proto");
-    println!("cargo:rerun-if-changed=src/proto/store_forward.proto");
 }