fix yojson: nested sum type was badly encoded

Author: c-cube

src/compilerlib/pb_codegen_encode_yojson.ml

@@ -133,17 +133,16 @@ let gen_rft_variant sc rf_label { Ot.v_constructors; _ } =
           let json_label =
             Pb_codegen_util.camel_case_of_constructor vc_constructor
           in
-          F.linep sc "| %s v ->" vc_constructor;
           F.sub_scope sc (fun sc ->
               match vc_field_type with
               | Ot.Vct_nullary ->
-                F.linep sc "(\"%s\", `Null) :: assoc" json_label
+                F.linep sc "| %s -> (\"%s\", `Null) :: assoc" vc_constructor json_label
               | Ot.Vct_non_nullary_constructor field_type ->
                 (match
                    gen_field var_name json_label field_type vc_payload_kind
                  with
-                | None -> F.linep sc "(\"%s\", `Null) :: assoc" json_label
-                | Some exp -> F.linep sc "%s :: assoc " exp)))
+                | None -> F.linep sc "| %s -> (\"%s\", `Null) :: assoc" vc_constructor json_label
+                | Some exp -> F.linep sc "| %s v -> %s :: assoc" vc_constructor exp)))
         v_constructors);
 
   F.linep sc "in (* match v.%s *)" rf_label

src/tests/yojson/dune

@@ -8,5 +8,5 @@
  (deps
   (:file yojson_unittest.proto))
  (action
-  (run %{project_root}/src/ocaml-protoc/ocaml_protoc.exe %{file} --yojson
+  (run %{project_root}/src/ocaml-protoc/ocaml_protoc.exe %{file} --yojson --pp
     --ml_out=.)))

src/tests/yojson/yojson_unittest.proto

@@ -27,6 +27,8 @@ message AllBasicTypes {
    repeated string    repeated14 = 34;
 }
 
+message Empty {}
+
 message SmallMessage {
   string sm_string = 1;
 }
@@ -74,3 +76,12 @@ message Test {
   repeated Enum repeated_enum = 10;
   repeated ABasicMessage basic = 11;
 }
+
+message NestedUnit {
+  oneof yolo {
+    int32 x = 1;
+    Empty empty = 2;
+  }
+
+  string other = 3;
+}