Link with serde when with-serde feature is enabled

protobuf-codegen-pure-test/Cargo.toml

@@ -12,6 +12,7 @@ bench = false
 default-features = []
 proto3 = []
 with-bytes = ["bytes", "protobuf/with-bytes", "protobuf-test-common/with-bytes"]
+with-serde = ["serde", "serde_derive", "serde_json", "protobuf/with-serde", "protobuf-test-common/with-serde"]
 
 [build-dependencies]
 protobuf-codegen-pure = { path = "../protobuf-codegen-pure" }
@@ -23,9 +24,9 @@ env_logger  = "0.5.*"
 [dependencies]
 protobuf-test-common = { path = "../protobuf-test-common" }
 protobuf-serde       = { path = "../protobuf-serde" }
-serde        = "1.0"
-serde_derive = "1.0"
-serde_json   = "1.0"
+serde        = { version = "1.0", optional = true }
+serde_derive = { version = "1.0", optional = true }
+serde_json   = { version = "1.0", optional = true }
 bytes = { version = "0.4", optional = true }
 
 [dependencies.protobuf]

protobuf-codegen-pure-test/src/lib.rs

@@ -9,10 +9,13 @@ extern crate protobuf_serde;
 #[cfg(feature = "with-bytes")]
 extern crate bytes;
 
+#[cfg(feature = "with-serde")]
 extern crate serde;
-extern crate serde_json;
+#[cfg(feature = "with-serde")]
 #[macro_use]
 extern crate serde_derive;
+#[cfg(feature = "with-serde")]
+extern crate serde_json;
 
 mod v2;
 mod v3;

protobuf-codegen/src/enums.rs

@@ -147,7 +147,7 @@ impl<'a> EnumGen<'a> {
             );
         }
         if self.customize.serde_derive.unwrap_or(false) {
-            derive.extend(&["Serialize", "Deserialize"]);
+            w.write_line("#[cfg_attr(feature = \"with-serde\", derive(Serialize, Deserialize))]");
         }
         w.derive(&derive);
         let ref type_name = self.type_name;

protobuf-codegen/src/message.rs

@@ -364,10 +364,10 @@ impl<'a> MessageGen<'a> {
         if self.lite_runtime {
             derive.push("Debug");
         }
+        w.derive(&derive);
         if self.serde_derive_enabled() {
-            derive.extend(&["Serialize", "Deserialize"]);
+            w.write_line("#[cfg_attr(feature = \"with-serde\", derive(Serialize, Deserialize))]");
         }
-        w.derive(&derive);
         w.pub_struct(&self.type_name, |w| {
             if !self.fields_except_oneof().is_empty() {
                 w.comment("message fields");
@@ -388,11 +388,11 @@ impl<'a> MessageGen<'a> {
             w.comment("special fields");
 
             if self.serde_derive_enabled() {
-                w.write_line("#[serde(skip)]");
+                w.write_line("#[cfg_attr(feature = \"with-serde\", serde(skip))]");
             }
             w.pub_field_decl("unknown_fields", "::protobuf::UnknownFields");
             if self.serde_derive_enabled() {
-                w.write_line("#[serde(skip)]");
+                w.write_line("#[cfg_attr(feature = \"with-serde\", serde(skip))]");
             }
             w.field_decl("cached_size", "::protobuf::CachedSize");
         });

protobuf-codegen/src/oneof.rs

@@ -157,7 +157,7 @@ impl<'a> OneofGen<'a> {
             derive.push("Debug");
         }
         if self.customize.serde_derive.unwrap_or(false) {
-            derive.extend(&["Serialize", "Deserialize"]);
+            w.write_line("#[cfg_attr(feature = \"with-serde\", derive(Serialize, Deserialize))]");
         }
         w.derive(&derive);
         w.pub_enum(&self.type_name.to_string(), |w| {

protobuf-test-common/Cargo.toml

@@ -15,15 +15,16 @@ bench = false
 default-features = []
 proto3 = []
 with-bytes = ["bytes", "protobuf/with-bytes"]
+with-serde = ["serde", "protobuf/with-serde"]
 
 [dependencies]
 glob         = "0.2"
 log          = "0.*"
 env_logger   = "0.5.*"
 tempfile     = "3.0"
-serde        = "1.0"
-serde_derive = "1.0"
-serde_json   = "1.0"
+serde        = { version = "1.0", optional = true }
+serde_derive = { version = "1.0", optional = true }
+serde_json   = { version = "1.0", optional = true }
 bytes = { version = "0.4", optional = true }
 
 [dependencies.protobuf]

protobuf-test/Cargo.toml

@@ -12,6 +12,7 @@ bench = false
 default-features = []
 proto3 = []
 with-bytes = ["bytes", "protobuf/with-bytes", "protobuf-test-common/with-bytes"]
+with-serde = ["serde", "serde_derive", "serde_json", "protobuf/with-serde", "protobuf-test-common/with-serde"]
 
 [build-dependencies]
 protoc      = { path = "../protoc" }
@@ -24,9 +25,9 @@ env_logger  = "0.5.*"
 [dependencies]
 protobuf-test-common = { path = "../protobuf-test-common" }
 protobuf-serde       = { path = "../protobuf-serde" }
-serde        = "1.0"
-serde_derive = "1.0"
-serde_json   = "1.0"
+serde        = { version = "1.0", optional = true }
+serde_derive = { version = "1.0", optional = true }
+serde_json   = { version = "1.0", optional = true }
 bytes = { version = "0.4", optional = true }
 
 [dependencies.protobuf]

protobuf-test/src/common/v2/test_serde_derive.rs

@@ -1,5 +1,9 @@
-use super::test_serde_derive_pb::*;
+#![cfg(feature = "with-serde")]
+
 use serde_json;
+
+use super::test_serde_derive_pb::*;
+
 use std::collections::HashMap;
 
 #[test]

protobuf-test/src/lib.rs

@@ -9,10 +9,13 @@ extern crate protobuf_serde;
 #[cfg(feature = "with-bytes")]
 extern crate bytes;
 
+#[cfg(feature = "with-serde")]
 extern crate serde;
-extern crate serde_json;
+#[cfg(feature = "with-serde")]
 #[macro_use]
 extern crate serde_derive;
+#[cfg(feature = "with-serde")]
+extern crate serde_json;
 
 mod v2;
 

protobuf/src/lib.rs

@@ -7,7 +7,12 @@
 
 #[cfg(feature = "bytes")]
 extern crate bytes;
+#[cfg(feature = "with-serde")]
+extern crate serde;
+#[macro_use]
+#[cfg(feature = "with-serde")]
 
+extern crate serde_derive;
 pub use unknown::UnknownFields;
 pub use unknown::UnknownFieldsIter;
 pub use unknown::UnknownValue;