[pigeon] allow gen of unused classes (#7529)

changes pigeon_lib to allow generation of classes that aren't referenced in any API.

Author: tarrinneal

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 22.1.0
+
+* Allows generation of classes that aren't referenced in an API.
+
 ## 22.0.0
 
 * [dart] Changes codec to send int64 instead of int32.

packages/pigeon/lib/ast.dart

@@ -652,6 +652,7 @@ class Class extends Node {
   Class({
     required this.name,
     required this.fields,
+    this.isReferenced = true,
     this.isSwiftClass = false,
     this.documentationComments = const <String>[],
   });
@@ -662,6 +663,9 @@ class Class extends Node {
   /// All the fields contained in the class.
   List<NamedType> fields;
 
+  /// Whether the class is referenced in any API.
+  bool isReferenced;
+
   /// Determines whether the defined class should be represented as a struct or
   /// a class in Swift generation.
   ///

packages/pigeon/lib/generator_tools.dart

@@ -13,7 +13,7 @@ import 'ast.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '22.0.0';
+const String pigeonVersion = '22.1.0';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/pigeon_lib.dart

@@ -1393,23 +1393,24 @@ class _RootBuilder extends dart_ast_visitor.RecursiveAstVisitor<Object?> {
         getReferencedTypes(_apis, _classes);
     final Set<String> referencedTypeNames =
         referencedTypes.keys.map((TypeDeclaration e) => e.baseName).toSet();
-    final List<Class> referencedClasses = List<Class>.from(_classes);
-    referencedClasses
-        .removeWhere((Class x) => !referencedTypeNames.contains(x.name));
+    final List<Class> nonReferencedClasses = List<Class>.from(_classes);
+    nonReferencedClasses
+        .removeWhere((Class x) => referencedTypeNames.contains(x.name));
+    for (final Class x in nonReferencedClasses) {
+      x.isReferenced = false;
+    }
 
     final List<Enum> referencedEnums = List<Enum>.from(_enums);
     final Root completeRoot =
-        Root(apis: _apis, classes: referencedClasses, enums: referencedEnums);
+        Root(apis: _apis, classes: _classes, enums: referencedEnums);
 
     final List<Error> validateErrors = _validateAst(completeRoot, source);
     final List<Error> totalErrors = List<Error>.from(_errors);
     totalErrors.addAll(validateErrors);
 
     for (final MapEntry<TypeDeclaration, List<int>> element
         in referencedTypes.entries) {
-      if (!referencedClasses
-              .map((Class e) => e.name)
-              .contains(element.key.baseName) &&
+      if (!_classes.map((Class e) => e.name).contains(element.key.baseName) &&
           !referencedEnums
               .map((Enum e) => e.name)
               .contains(element.key.baseName) &&
@@ -1430,7 +1431,7 @@ class _RootBuilder extends dart_ast_visitor.RecursiveAstVisitor<Object?> {
             lineNumber: lineNumber));
       }
     }
-    for (final Class classDefinition in referencedClasses) {
+    for (final Class classDefinition in _classes) {
       classDefinition.fields = _attachAssociatedDefinitions(
         classDefinition.fields,
       );

packages/pigeon/pigeons/core_tests.dart

@@ -18,14 +18,11 @@ enum AnotherEnum {
   justInCase,
 }
 
-class SimpleClass {
-  SimpleClass({
-    this.aString,
-    this.aBool = true,
-  });
+// This exists to show that unused data classes still generate.
+class UnusedClass {
+  UnusedClass({this.aField});
 
-  String? aString;
-  bool aBool;
+  Object? aField;
 }
 
 /// A class containing all supported types.

packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/AlternateLanguageTestPlugin.java

@@ -688,6 +688,10 @@ public void error(Throwable error) {
         };
     flutterSmallApiOne.echoString(aString, resultCallbackOne);
   }
+
+  public @NonNull CoreTests.UnusedClass testIfUnusedClassIsGenerated() {
+    return new CoreTests.UnusedClass();
+  }
 }
 
 class TestPluginWithSuffix implements CoreTests.HostSmallApi {

packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/CoreTests.java

@@ -99,6 +99,67 @@ public enum AnotherEnum {
     }
   }
 
+  /** Generated class from Pigeon that represents data sent in messages. */
+  public static final class UnusedClass {
+    private @Nullable Object aField;
+
+    public @Nullable Object getAField() {
+      return aField;
+    }
+
+    public void setAField(@Nullable Object setterArg) {
+      this.aField = setterArg;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (this == o) {
+        return true;
+      }
+      if (o == null || getClass() != o.getClass()) {
+        return false;
+      }
+      UnusedClass that = (UnusedClass) o;
+      return Objects.equals(aField, that.aField);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(aField);
+    }
+
+    public static final class Builder {
+
+      private @Nullable Object aField;
+
+      @CanIgnoreReturnValue
+      public @NonNull Builder setAField(@Nullable Object setterArg) {
+        this.aField = setterArg;
+        return this;
+      }
+
+      public @NonNull UnusedClass build() {
+        UnusedClass pigeonReturn = new UnusedClass();
+        pigeonReturn.setAField(aField);
+        return pigeonReturn;
+      }
+    }
+
+    @NonNull
+    ArrayList<Object> toList() {
+      ArrayList<Object> toListResult = new ArrayList<>(1);
+      toListResult.add(aField);
+      return toListResult;
+    }
+
+    static @NonNull UnusedClass fromList(@NonNull ArrayList<Object> pigeonVar_list) {
+      UnusedClass pigeonResult = new UnusedClass();
+      Object aField = pigeonVar_list.get(0);
+      pigeonResult.setAField(aField);
+      return pigeonResult;
+    }
+  }
+
   /**
    * A class containing all supported types.
    *
@@ -2043,14 +2104,16 @@ protected Object readValueOfType(byte type, @NonNull ByteBuffer buffer) {
             return value == null ? null : AnotherEnum.values()[((Long) value).intValue()];
           }
         case (byte) 131:
-          return AllTypes.fromList((ArrayList<Object>) readValue(buffer));
+          return UnusedClass.fromList((ArrayList<Object>) readValue(buffer));
         case (byte) 132:
-          return AllNullableTypes.fromList((ArrayList<Object>) readValue(buffer));
+          return AllTypes.fromList((ArrayList<Object>) readValue(buffer));
         case (byte) 133:
-          return AllNullableTypesWithoutRecursion.fromList((ArrayList<Object>) readValue(buffer));
+          return AllNullableTypes.fromList((ArrayList<Object>) readValue(buffer));
         case (byte) 134:
-          return AllClassesWrapper.fromList((ArrayList<Object>) readValue(buffer));
+          return AllNullableTypesWithoutRecursion.fromList((ArrayList<Object>) readValue(buffer));
         case (byte) 135:
+          return AllClassesWrapper.fromList((ArrayList<Object>) readValue(buffer));
+        case (byte) 136:
           return TestMessage.fromList((ArrayList<Object>) readValue(buffer));
         default:
           return super.readValueOfType(type, buffer);
@@ -2065,20 +2128,23 @@ protected void writeValue(@NonNull ByteArrayOutputStream stream, Object value) {
       } else if (value instanceof AnotherEnum) {
         stream.write(130);
         writeValue(stream, value == null ? null : ((AnotherEnum) value).index);
-      } else if (value instanceof AllTypes) {
+      } else if (value instanceof UnusedClass) {
         stream.write(131);
+        writeValue(stream, ((UnusedClass) value).toList());
+      } else if (value instanceof AllTypes) {
+        stream.write(132);
         writeValue(stream, ((AllTypes) value).toList());
       } else if (value instanceof AllNullableTypes) {
-        stream.write(132);
+        stream.write(133);
         writeValue(stream, ((AllNullableTypes) value).toList());
       } else if (value instanceof AllNullableTypesWithoutRecursion) {
-        stream.write(133);
+        stream.write(134);
         writeValue(stream, ((AllNullableTypesWithoutRecursion) value).toList());
       } else if (value instanceof AllClassesWrapper) {
-        stream.write(134);
+        stream.write(135);
         writeValue(stream, ((AllClassesWrapper) value).toList());
       } else if (value instanceof TestMessage) {
-        stream.write(135);
+        stream.write(136);
         writeValue(stream, ((TestMessage) value).toList());
       } else {
         super.writeValue(stream, value);

packages/pigeon/platform_tests/alternate_language_test_plugin/example/ios/RunnerTests/AllDatatypesTest.m

@@ -100,4 +100,8 @@ - (void)testAllEquals {
   [self waitForExpectations:@[ expectation ] timeout:1.0];
 }
 
+- (void)unusedClassesExist {
+  XCTAssert([[FLTUnusedClass alloc] init] != nil);
+}
+
 @end

packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/AlternateLanguageTestPlugin.m

@@ -733,6 +733,10 @@ - (void)callFlutterSmallApiEchoString:(nonnull NSString *)aString
       }];
 }
 
+- (FLTUnusedClass *)checkIfUnusedClassGenerated {
+  return [[FLTUnusedClass alloc] init];
+}
+
 @end
 
 @interface AlternateLanguageTestAPIWithSuffix ()

packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.h

@@ -38,12 +38,18 @@ typedef NS_ENUM(NSUInteger, FLTAnotherEnum) {
 - (instancetype)initWithValue:(FLTAnotherEnum)value;
 @end
 
+@class FLTUnusedClass;
 @class FLTAllTypes;
 @class FLTAllNullableTypes;
 @class FLTAllNullableTypesWithoutRecursion;
 @class FLTAllClassesWrapper;
 @class FLTTestMessage;
 
+@interface FLTUnusedClass : NSObject
++ (instancetype)makeWithAField:(nullable id)aField;
+@property(nonatomic, strong, nullable) id aField;
+@end
+
 /// A class containing all supported types.
 @interface FLTAllTypes : NSObject
 /// `init` unavailable to enforce nonnull fields, see the `make` class method.