[pigeon] Encode custom enum as long in Kotlin generator (#10085)

This PR ensures that custom enums are encoded as the expected `Long` type in the Kotlin generator. 

Without this change it is not possible to perform encoding <-> decoding in Kotlin, because enums are generated to have an `Int` raw value and encoded without first casting to `Long`.

Fixes: flutter/flutter#176081

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Author: devgianlu

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 26.0.5
+
+* [kotlin] Serialize custom enums as `Long` instead of `Int` to avoid `ClassCastException` on decoding.
+
 ## 26.0.4
 
 * Adds compatibility with `analyzer` 8.x.

packages/pigeon/example/app/android/app/src/main/kotlin/dev/flutter/pigeon_example_app/Messages.g.kt

@@ -142,7 +142,7 @@ private open class MessagesPigeonCodec : StandardMessageCodec() {
     when (value) {
       is Code -> {
         stream.write(129)
-        writeValue(stream, value.raw)
+        writeValue(stream, value.raw.toLong())
       }
       is MessageData -> {
         stream.write(130)

packages/pigeon/lib/src/generator_tools.dart

@@ -15,7 +15,7 @@ import 'generator.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '26.0.4';
+const String pigeonVersion = '26.0.5';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/src/kotlin/kotlin_generator.dart

@@ -475,7 +475,9 @@ class KotlinGenerator extends StructuredGenerator<InternalKotlinOptions> {
 
     void writeEncodeLogic(EnumeratedType customType) {
       final String encodeString =
-          customType.type == CustomTypes.customClass ? 'toList()' : 'raw';
+          customType.type == CustomTypes.customClass
+              ? 'toList()'
+              : 'raw.toLong()';
       final String valueString =
           customType.enumeration < maximumCodecFieldKey
               ? 'value.$encodeString'

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/CoreTests.gen.kt

@@ -704,11 +704,11 @@ private open class CoreTestsPigeonCodec : StandardMessageCodec() {
     when (value) {
       is AnEnum -> {
         stream.write(129)
-        writeValue(stream, value.raw)
+        writeValue(stream, value.raw.toLong())
       }
       is AnotherEnum -> {
         stream.write(130)
-        writeValue(stream, value.raw)
+        writeValue(stream, value.raw.toLong())
       }
       is UnusedClass -> {
         stream.write(131)

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/EventChannelTests.gen.kt

@@ -477,11 +477,11 @@ private open class EventChannelTestsPigeonCodec : StandardMessageCodec() {
     when (value) {
       is EventEnum -> {
         stream.write(129)
-        writeValue(stream, value.raw)
+        writeValue(stream, value.raw.toLong())
       }
       is AnotherEventEnum -> {
         stream.write(130)
-        writeValue(stream, value.raw)
+        writeValue(stream, value.raw.toLong())
       }
       is EventAllNullableTypes -> {
         stream.write(131)

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/ProxyApiTests.gen.kt

@@ -560,7 +560,7 @@ private open class ProxyApiTestsPigeonCodec : StandardMessageCodec() {
     when (value) {
       is ProxyApiTestEnum -> {
         stream.write(129)
-        writeValue(stream, value.raw)
+        writeValue(stream, value.raw.toLong())
       }
       else -> super.writeValue(stream, value)
     }

packages/pigeon/platform_tests/test_plugin/android/src/test/kotlin/com/example/test_plugin/AllDatatypesTest.kt

@@ -46,33 +46,52 @@ internal class AllDatatypesTest {
   }
 
   @Test
-  fun testHasValues() {
+  fun testRoundtripNullValues() {
+    val everything = AllNullableTypes()
+    val codec = FlutterIntegrationCoreApi.codec
+    val encoded = codec.encodeMessage(everything)
+    encoded?.rewind()
+    val decoded = codec.decodeMessage(encoded)
+    assertEquals(everything, decoded)
+  }
+
+  fun getFullyPopulatedAllNullableTypes(): AllNullableTypes {
     val stringList = listOf("string", "another one")
-    val everything =
-        AllNullableTypes(
-            aNullableBool = false,
-            aNullableInt = 1234L,
-            aNullableDouble = 2.0,
-            aNullableString = "hello",
-            aNullableByteArray = byteArrayOf(1, 2, 3, 4),
-            aNullable4ByteArray = intArrayOf(1, 2, 3, 4),
-            aNullable8ByteArray = longArrayOf(1, 2, 3, 4),
-            aNullableFloatArray = doubleArrayOf(0.5, 0.25, 1.5, 1.25),
-            aNullableObject = 0,
-            list = listOf(1, 2, 3),
-            stringList = stringList,
-            boolList = listOf(true, false),
-            intList = listOf(1, 2),
-            doubleList = listOf(1.1, 2.2),
-            objectList = listOf(1, 2, 3),
-            listList = listOf(stringList, stringList.toList()),
-            mapList = listOf(mapOf("hello" to 1234), mapOf("hello" to 1234)),
-            map = mapOf("hello" to 1234),
-            stringMap = mapOf("hello" to "you"),
-            intMap = mapOf(1L to 0L),
-            objectMap = mapOf("hello" to 1234),
-            listMap = mapOf(1L to stringList),
-            mapMap = mapOf(1L to mapOf()))
+
+    return AllNullableTypes(
+        aNullableBool = false,
+        aNullableInt = 1234L,
+        aNullableDouble = 2.0,
+        aNullableString = "hello",
+        aNullableByteArray = byteArrayOf(1, 2, 3, 4),
+        aNullable4ByteArray = intArrayOf(1, 2, 3, 4),
+        aNullable8ByteArray = longArrayOf(1, 2, 3, 4),
+        aNullableFloatArray = doubleArrayOf(0.5, 0.25, 1.5, 1.25),
+        aNullableEnum = AnEnum.TWO,
+        anotherNullableEnum = AnotherEnum.JUST_IN_CASE,
+        aNullableObject = 0,
+        list = listOf(1, 2, 3),
+        stringList = stringList,
+        boolList = listOf(true, false),
+        enumList = listOf(AnEnum.ONE, AnEnum.TWO),
+        intList = listOf(1, 2),
+        doubleList = listOf(1.1, 2.2),
+        objectList = listOf(1, 2, 3),
+        listList = listOf(stringList, stringList.toList()),
+        mapList = listOf(mapOf("hello" to 1234), mapOf("hello" to 1234)),
+        map = mapOf("hello" to 1234),
+        stringMap = mapOf("hello" to "you"),
+        intMap = mapOf(1L to 0L),
+        objectMap = mapOf("hello" to 1234),
+        enumMap =
+            mapOf(AnEnum.ONE to AnEnum.FORTY_TWO, AnEnum.TWO to AnEnum.FOUR_HUNDRED_TWENTY_TWO),
+        listMap = mapOf(1L to stringList),
+        mapMap = mapOf(1L to mapOf()))
+  }
+
+  @Test
+  fun testHasValues() {
+    val everything = getFullyPopulatedAllNullableTypes()
     val binaryMessenger = mockk<BinaryMessenger>()
     val api = FlutterIntegrationCoreApi(binaryMessenger)
 
@@ -97,6 +116,16 @@ internal class AllDatatypesTest {
     assertTrue(didCall)
   }
 
+  @Test
+  fun testRoundtripHasValues() {
+    val everything = getFullyPopulatedAllNullableTypes()
+    val codec = FlutterIntegrationCoreApi.codec
+    val encoded = codec.encodeMessage(everything)
+    encoded?.rewind()
+    val decoded = codec.decodeMessage(encoded)
+    assertEquals(everything, decoded)
+  }
+
   private val correctList = listOf<Any?>("a", 2, "three")
   private val matchingList = correctList.toMutableList()
   private val differentList = listOf<Any?>("a", 2, "three", 4.0)

packages/pigeon/pubspec.yaml

@@ -2,7 +2,7 @@ name: pigeon
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 repository: https://github.com/flutter/packages/tree/main/packages/pigeon
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+pigeon%22
-version: 26.0.4 # This must match the version in lib/src/generator_tools.dart
+version: 26.0.5 # This must match the version in lib/src/generator_tools.dart
 
 environment:
   sdk: ^3.7.0