Add protobuf source comment support to generated Rust code

.github/workflows/ci.yml

@@ -128,6 +128,7 @@ jobs:
           # /usr/local/include) so the checked-in code is pinned to a
           # specific proto source, not whatever protoc version ships.
           protoc --descriptor_set_out=/tmp/wkt.pb --include_imports \
+              --include_source_info \
               -I buffa-types/protos \
               google/protobuf/any.proto \
               google/protobuf/duration.proto \

Taskfile.yml

@@ -433,7 +433,7 @@ tasks:
       Requires protoc on PATH.
     cmds:
       - >-
-        protoc --descriptor_set_out=/tmp/wkt.pb --include_imports
+        protoc --descriptor_set_out=/tmp/wkt.pb --include_imports --include_source_info
         -I buffa-types/protos
         google/protobuf/any.proto
         google/protobuf/duration.proto

buffa-build/src/lib.rs

@@ -519,6 +519,7 @@ fn invoke_protoc(
 
     let mut cmd = Command::new(&protoc);
     cmd.arg("--include_imports");
+    cmd.arg("--include_source_info");
     cmd.arg(format!(
         "--descriptor_set_out={}",
         descriptor_path.display()
@@ -555,6 +556,9 @@ fn invoke_protoc(
 /// module-root-relative; passing user paths to both would be a contradiction.
 /// Codegen filtering happens on our side via `files_to_generate` matching.
 fn invoke_buf() -> Result<Vec<u8>, Box<dyn std::error::Error>> {
+    // buf build includes SourceCodeInfo by default (there's an
+    // --exclude-source-info flag to disable it), so proto comments
+    // propagate to generated code without an explicit opt-in here.
     let output = Command::new("buf")
         .arg("build")
         .arg("--as-file-descriptor-set")