Use field options in proto3 instead of adding an extra property

Author: martin-traverse

cli/targets/static.js

@@ -371,7 +371,12 @@ function syntaxForType(type) {
 
 function isOptional(field, syntax) {
 
-    return (syntax === "proto3") ? field.proto3Optional : field.optional;
+    // In proto3, optional fields are explicit
+    if (syntax === "proto3")
+        return field.options != null && field.options["proto3_optional"] === true;
+
+    // In proto2, fields are explicitly optional if they are not part of a map, array or oneOf group
+    return field.optional && !(field.partOf || field.repeated || field.map);
 }
 
 function buildType(ref, type) {

src/field.js

@@ -78,13 +78,6 @@ function Field(name, id, type, rule, extend, options, comment) {
     if (extend !== undefined && !util.isString(extend))
         throw TypeError("extend must be a string");
 
-    /**
-     * Explicit record of the proto3 optional rule
-     * Needed to stop the proto3 optional semantics from getting lost
-     * @type {boolean}
-     */
-    this.proto3Optional = rule === "proto3_optional";
-
     /**
      * Field rule, if any.
      * @type {string|undefined}