feature(protoc-gen-prost-serde): add "feature" option

example/build-with-buf/Cargo.toml

@@ -4,7 +4,8 @@ version = "0.1.0"
 edition = "2021"
 
 [features]
-default = ["proto_full"]
+default = ["proto_full", "serde"]
+serde = ["dep:serde"]
 # @@protoc_deletion_point(features)
 # This section is automatically generated by protoc-gen-prost-crate.
 # Changes in this area may be lost on regeneration.
@@ -17,7 +18,7 @@ bytes = "1.10.1"
 prost = "0.14.1"
 pbjson = "0.8.0"
 pbjson-types = "0.8.0"
-serde = "1.0.228"
+serde = { version = "1.0.228", optional = true }
 tonic = { version = "0.14.2", features = ["gzip"] }
 tonic-prost = "0.14.2"
 

example/build-with-buf/buf.gen.yaml

@@ -12,6 +12,8 @@ plugins:
   - local: protoc-gen-prost-serde
     #path: ../../target/debug/protoc-gen-prost-serde
     out: src/gen
+    opt:
+      - feature
   - local: protoc-gen-tonic
     #path: ../../target/debug/protoc-gen-tonic
     out: src/gen

protoc-gen-prost-serde/README.md

@@ -48,6 +48,9 @@ In addition, the following options can also be specified:
   by `protoc-gen-prost`. This behavior may be desired if this plugin is run
   in a separate `protoc` invocation and you encounter a `Tried to insert into
   file that doesn't exist` error.
+* `feature(=<string>)`:  Adds feature gate to all generated includes. If `no_include`
+  is set, this option has no effect. If the `<string>` value is not specified,
+  default feature name `"serde"` will be used.
 
 A note on parameter values:
 

protoc-gen-prost-serde/src/generator.rs

@@ -8,6 +8,7 @@ pub struct PbJsonGenerator {
     builder: pbjson_build::Builder,
     prefixes: Vec<String>,
     insert_include: bool,
+    feature_name: Option<String>,
 }
 
 impl Generator for PbJsonGenerator {
@@ -27,6 +28,11 @@ impl Generator for PbJsonGenerator {
 
                 if self.insert_include {
                     res.push(request.append_to_file(|buf| {
+                        if let Some(feature_name) = &self.feature_name {
+                            buf.push_str("#[cfg(feature = \"");
+                            buf.push_str(feature_name);
+                            buf.push_str("\")]\n");
+                        }
                         buf.push_str("include!(\"");
                         buf.push_str(&output_filename);
                         buf.push_str("\");\n");
@@ -55,11 +61,16 @@ impl Generator for PbJsonGenerator {
 }
 
 impl PbJsonGenerator {
-    pub fn new(builder: pbjson_build::Builder, insert_include: bool) -> Self {
+    pub fn new(
+        builder: pbjson_build::Builder,
+        insert_include: bool,
+        feature_name: Option<String>,
+    ) -> Self {
         Self {
             builder,
             prefixes: vec![".".to_owned()],
             insert_include,
+            feature_name,
         }
     }
 }

protoc-gen-prost-serde/src/lib.rs

@@ -28,7 +28,8 @@ pub fn execute(raw_request: &[u8]) -> protoc_gen_prost::Result {
         params.flat_output_dir,
     )?;
 
-    let files = PbJsonGenerator::new(builder, !params.no_include).generate(&module_request_set)?;
+    let files = PbJsonGenerator::new(builder, !params.no_include, params.feature)
+        .generate(&module_request_set)?;
 
     Ok(files)
 }
@@ -49,6 +50,7 @@ struct Parameters {
     btree_map: Vec<String>,
     flat_output_dir: bool,
     exclude: Vec<String>,
+    feature: Option<String>,
 }
 
 impl Parameters {
@@ -93,6 +95,9 @@ impl Parameters {
     }
 }
 
+/// This name will be used as a gate feature name when "feature" parameter is passed without value
+const DEFAULT_FEATURE_NAME: &str = "serde";
+
 impl str::FromStr for Parameters {
     type Err = InvalidParameter;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
@@ -184,6 +189,13 @@ impl str::FromStr for Parameters {
                     param: "exclude",
                     value: prefix,
                 } => ret_val.exclude.push(prefix.to_string()),
+                Param::Parameter { param: "feature" } => {
+                    ret_val.feature = Some(DEFAULT_FEATURE_NAME.to_string())
+                }
+                Param::Value {
+                    param: "feature",
+                    value,
+                } => ret_val.feature = Some(value.to_string()),
                 _ => return Err(InvalidParameter::from(param)),
             }
         }