#39: Validate first enum value for proto3 (must be zero)

Author: kshchepanovskyi

src/main/java/io/protostuff/jetbrains/plugin/annotator/ProtoErrorsAnnotator.java

@@ -80,6 +80,7 @@ public void annotate(@NotNull PsiElement element, @NotNull AnnotationHolder hold
                     List<EnumConstantNode> constants = anEnum.getConstants();
                     checkDuplicateEnumConstantNames(constants);
                     checkDuplicateEnumConstantValues(anEnum, constants);
+                    checkFirstEnumConstantValueIsZero(anEnum, constants, syntax);
                 } else if (element instanceof ServiceNode) {
                     ServiceNode service = (ServiceNode) element;
                     List<RpcMethodNode> rpcMethods = service.getRpcMethods();
@@ -90,6 +91,20 @@ public void annotate(@NotNull PsiElement element, @NotNull AnnotationHolder hold
         }
     }
 
+    private void checkFirstEnumConstantValueIsZero(EnumNode anEnum, List<EnumConstantNode> constants, Syntax syntax) {
+        if (syntax != Syntax.PROTO3) {
+            return;
+        }
+        if (constants.isEmpty()) {
+            return;
+        }
+        EnumConstantNode first = constants.get(0);
+        if (first.getConstantValue() != 0) {
+            String message = message("error.first.enum.value.should.be.zero");
+            markError(first.getConstantValueNode(), null, message);
+        }
+    }
+
     private void checkExtendNodeDeprecated(ExtendNode element, Syntax syntax) {
         if (syntax != Syntax.PROTO3) {
             return;

src/main/resources/io/protostuff/protobuf-jetbrains-plugin/messages/ProtostuffBundle.properties

@@ -26,3 +26,4 @@ error.illegal.field.label=Field label "{0}" is not allowed in proto3
 error.default.value.not.supported=Default values are not supported in proto3
 error.groups.not.supported=Groups are not supported in proto3
 error.extensions.not.supported=Extensions are not supported in proto3
+error.first.enum.value.should.be.zero=First enum value must be zero in proto3

src/test/java/io/protostuff/jetbrains/plugin/annotator/ProtoErrorsAnnotatorTest.java

@@ -90,6 +90,10 @@ public void testProto3IllegalExtend() {
         check();
     }
 
+    public void testProto3IllegalFirstEnumValue() {
+        check();
+    }
+
     private void check() {
         String file = getTestName(false) + ".proto";
         myFixture.configureByFiles(file);

src/test/resources/annotator/Proto3IllegalFirstEnumValue.proto

@@ -0,0 +1,7 @@
+syntax = "proto3";
+
+package annotator;
+
+enum TestEnum {
+    UNKNOWN = <error descr="First enum value must be zero in proto3">1</error>;
+}