[C#] Fix retrieving enumeration vectors as arrays (#5457)

* [C#] Fix retrieving enumeration vectors as arrays

* [C#] Don't generate CreateVectorBlock for enums

src/idl_gen_general.cpp

@@ -1238,12 +1238,31 @@ class GeneralGenerator : public BaseGenerator {
             code += GenTypeBasic(field.value.type.VectorType());
             code += "[] Get";
             code += MakeCamel(field.name, lang_.first_camel_upper);
-            code += "Array() { return ";
-            code += lang_.accessor_prefix + "__vector_as_array<";
-            code += GenTypeBasic(field.value.type.VectorType());
-            code += ">(";
-            code += NumToString(field.value.offset);
-            code += "); }\n";
+            code += "Array() { ";
+            if (IsEnum(field.value.type.VectorType())) {
+              // Since __vector_as_array does not work for enum types,
+              // fill array using an explicit loop.
+              code += "int o = " + lang_.accessor_prefix + "__offset(";
+              code += NumToString(field.value.offset);
+              code += "); if (o == 0) return null; int p = ";
+              code += lang_.accessor_prefix + "__vector(o); int l = ";
+              code += lang_.accessor_prefix + "__vector_len(o); ";
+              code += GenTypeBasic(field.value.type.VectorType());
+              code += "[] a = new ";
+              code += GenTypeBasic(field.value.type.VectorType());
+              code += "[l]; for (int i = 0; i < l; i++) { a[i] = " + getter;
+              code += "(p + i * ";
+              code += NumToString(InlineSize(field.value.type.VectorType()));
+              code += "); } return a;";
+            } else {
+              code += "return ";
+              code += lang_.accessor_prefix + "__vector_as_array<";
+              code += GenTypeBasic(field.value.type.VectorType());
+              code += ">(";
+              code += NumToString(field.value.offset);
+              code += ");";
+            }
+            code += " }\n";
             break;
           default: break;
         }
@@ -1476,7 +1495,10 @@ class GeneralGenerator : public BaseGenerator {
             code += "); return ";
             code += "builder." + FunctionStart('E') + "ndVector(); }\n";
             // For C#, include a block copy method signature.
-            if (lang_.language == IDLOptions::kCSharp) {
+            // Skip if the vector is of enums, because builder.Add
+            // throws an exception when supplied an enum array.
+            if (lang_.language == IDLOptions::kCSharp &&
+                !IsEnum(vector_type)) {
               code += "  public static " + GenVectorOffsetType() + " ";
               code += FunctionStart('C') + "reate";
               code += MakeCamel(field.name);

tests/FlatBuffers.Test/FlatBuffersExampleTests.cs

@@ -292,6 +292,25 @@ namespace FlatBuffers.Test
             Assert.AreEqual("Monster", Any.Monster.ToString());
         }
 
+        [FlatBuffersTestMethod]
+        public void TestVectorOfEnums()
+        {
+            const string monsterName = "TestVectorOfEnumsMonster";
+            var colorVec = new Color[] { Color.Red, Color.Green, Color.Blue };
+            var fbb = new FlatBufferBuilder(32);
+            var str1 = fbb.CreateString(monsterName);
+            var vec1 = Monster.CreateVectorOfEnumsVector(fbb, colorVec);
+            Monster.StartMonster(fbb);
+            Monster.AddName(fbb, str1);
+            Monster.AddVectorOfEnums(fbb, vec1);
+            var monster1 = Monster.EndMonster(fbb);
+            Monster.FinishMonsterBuffer(fbb, monster1);
+
+            var mons = Monster.GetRootAsMonster(fbb.DataBuffer);
+            var colors = mons.GetVectorOfEnumsArray();
+            Assert.ArrayEqual(colorVec, colors);
+        }
+
         [FlatBuffersTestMethod]
         public void TestNestedFlatBuffer()
         {

tests/MyGame/Example/Monster.cs

@@ -186,7 +186,7 @@ public struct Monster : IFlatbufferObject
 #else
   public ArraySegment<byte>? GetVectorOfEnumsBytes() { return __p.__vector_as_arraysegment(98); }
 #endif
-  public MyGame.Example.Color[] GetVectorOfEnumsArray() { return __p.__vector_as_array<MyGame.Example.Color>(98); }
+  public MyGame.Example.Color[] GetVectorOfEnumsArray() { int o = __p.__offset(98); if (o == 0) return null; int p = __p.__vector(o); int l = __p.__vector_len(o); MyGame.Example.Color[] a = new MyGame.Example.Color[l]; for (int i = 0; i < l; i++) { a[i] = (MyGame.Example.Color)__p.bb.Get(p + i * 1); } return a; }
   public bool MutateVectorOfEnums(int j, MyGame.Example.Color vector_of_enums) { int o = __p.__offset(98); if (o != 0) { __p.bb.Put(__p.__vector(o) + j * 1, (byte)vector_of_enums); return true; } else { return false; } }
 
   public static void StartMonster(FlatBufferBuilder builder) { builder.StartTable(48); }
@@ -283,7 +283,6 @@ public struct Monster : IFlatbufferObject
   public static void AddAnyAmbiguous(FlatBufferBuilder builder, int anyAmbiguousOffset) { builder.AddOffset(46, anyAmbiguousOffset, 0); }
   public static void AddVectorOfEnums(FlatBufferBuilder builder, VectorOffset vectorOfEnumsOffset) { builder.AddOffset(47, vectorOfEnumsOffset.Value, 0); }
   public static VectorOffset CreateVectorOfEnumsVector(FlatBufferBuilder builder, MyGame.Example.Color[] data) { builder.StartVector(1, data.Length, 1); for (int i = data.Length - 1; i >= 0; i--) builder.AddByte((byte)data[i]); return builder.EndVector(); }
-  public static VectorOffset CreateVectorOfEnumsVectorBlock(FlatBufferBuilder builder, MyGame.Example.Color[] data) { builder.StartVector(1, data.Length, 1); builder.Add(data); return builder.EndVector(); }
   public static void StartVectorOfEnumsVector(FlatBufferBuilder builder, int numElems) { builder.StartVector(1, numElems, 1); }
   public static Offset<MyGame.Example.Monster> EndMonster(FlatBufferBuilder builder) {
     int o = builder.EndTable();

tests/union_vector/Movie.cs

@@ -26,7 +26,7 @@ public struct Movie : IFlatbufferObject
 #else
   public ArraySegment<byte>? GetCharactersTypeBytes() { return __p.__vector_as_arraysegment(8); }
 #endif
-  public Character[] GetCharactersTypeArray() { return __p.__vector_as_array<Character>(8); }
+  public Character[] GetCharactersTypeArray() { int o = __p.__offset(8); if (o == 0) return null; int p = __p.__vector(o); int l = __p.__vector_len(o); Character[] a = new Character[l]; for (int i = 0; i < l; i++) { a[i] = (Character)__p.bb.Get(p + i * 1); } return a; }
   public bool MutateCharactersType(int j, Character characters_type) { int o = __p.__offset(8); if (o != 0) { __p.bb.Put(__p.__vector(o) + j * 1, (byte)characters_type); return true; } else { return false; } }
   public TTable? Characters<TTable>(int j) where TTable : struct, IFlatbufferObject { int o = __p.__offset(10); return o != 0 ? (TTable?)__p.__union<TTable>(__p.__vector(o) + j * 4 - __p.bb_pos) : null; }
   public int CharactersLength { get { int o = __p.__offset(10); return o != 0 ? __p.__vector_len(o) : 0; } }
@@ -49,7 +49,6 @@ public struct Movie : IFlatbufferObject
   public static void AddMainCharacter(FlatBufferBuilder builder, int mainCharacterOffset) { builder.AddOffset(1, mainCharacterOffset, 0); }
   public static void AddCharactersType(FlatBufferBuilder builder, VectorOffset charactersTypeOffset) { builder.AddOffset(2, charactersTypeOffset.Value, 0); }
   public static VectorOffset CreateCharactersTypeVector(FlatBufferBuilder builder, Character[] data) { builder.StartVector(1, data.Length, 1); for (int i = data.Length - 1; i >= 0; i--) builder.AddByte((byte)data[i]); return builder.EndVector(); }
-  public static VectorOffset CreateCharactersTypeVectorBlock(FlatBufferBuilder builder, Character[] data) { builder.StartVector(1, data.Length, 1); builder.Add(data); return builder.EndVector(); }
   public static void StartCharactersTypeVector(FlatBufferBuilder builder, int numElems) { builder.StartVector(1, numElems, 1); }
   public static void AddCharacters(FlatBufferBuilder builder, VectorOffset charactersOffset) { builder.AddOffset(3, charactersOffset.Value, 0); }
   public static VectorOffset CreateCharactersVector(FlatBufferBuilder builder, int[] data) { builder.StartVector(4, data.Length, 4); for (int i = data.Length - 1; i >= 0; i--) builder.AddOffset(data[i]); return builder.EndVector(); }