remove suspend_fun_to_async

jnigen/CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.6.0-dev.0
+* **Breaking Change** Removed `suspend_fun_to_async` flag from the config. It's now happening by default since we read the Kotlin's metadata and reliably identify the `suspend fun`s.
+
 ## 0.5.0
 * **Breaking Change** ([#72](https://github.com/dart-lang/jnigen/issues/72)): Removed support for `importMap` in favor of the newly added interop mechanism with importing yaml files.
 * **Breaking Change** ([#72](https://github.com/dart-lang/jnigen/issues/72)): `java.util.Set`, `java.util.Map`, `java.util.List`, `java.util.Iterator` and the boxed types like `java.lang.Integer`, `java.lang.Double`, ... will be generated as their corresponding classes in `package:jni`.

jnigen/java/src/main/java/com/github/dart_lang/jnigen/apisummarizer/elements/KotlinFunction.java

@@ -5,10 +5,8 @@
 package com.github.dart_lang.jnigen.apisummarizer.elements;
 
 import kotlinx.metadata.Flag;
-import kotlinx.metadata.FlagsKt;
 import kotlinx.metadata.KmFunction;
 import kotlinx.metadata.jvm.JvmExtensionsKt;
-import kotlinx.metadata.jvm.internal.JvmFunctionExtension;
 
 import java.util.List;
 import java.util.stream.Collectors;

jnigen/lib/src/bindings/kotlin_processor.dart

@@ -0,0 +1,56 @@
+// Copyright (c) 2023, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import '../elements/elements.dart';
+import 'visitor.dart';
+
+class KotlinProcessor extends Visitor<Classes, void> {
+  @override
+  void visit(Classes node) {
+    final classProcessor = _KotlinClassProcessor();
+    for (final classDecl in node.decls.values) {
+      classDecl.accept(classProcessor);
+    }
+  }
+}
+
+class _KotlinClassProcessor extends Visitor<ClassDecl, void> {
+  @override
+  void visit(ClassDecl node) {
+    if (node.kotlinClass == null) {
+      return;
+    }
+    // This [ClassDecl] is actually a Kotlin class.
+    // Matching methods and functions from the metadata.
+    final functions = <String, KotlinFunction>{};
+    for (final function in node.kotlinClass!.functions) {
+      functions[function.descriptor] = function;
+    }
+    for (final method in node.methods) {
+      if (functions.containsKey(method.descriptor!)) {
+        method.accept(_KotlinMethodProcessor(functions[method.descriptor!]!));
+      }
+    }
+  }
+}
+
+class _KotlinMethodProcessor extends Visitor<Method, void> {
+  final KotlinFunction function;
+
+  _KotlinMethodProcessor(this.function);
+
+  @override
+  void visit(Method node) {
+    if (function.isSuspend) {
+      const kotlinContinutationType = 'kotlin.coroutines.Continuation';
+      assert(node.params.isNotEmpty &&
+          node.params.last.type.kind == Kind.declared &&
+          node.params.last.type.name == kotlinContinutationType);
+      final continuationType = node.params.last.type.type as DeclaredType;
+      node.asyncReturnType = continuationType.params.isEmpty
+          ? TypeUsage.object
+          : continuationType.params.first;
+    }
+  }
+}

jnigen/lib/src/bindings/linker.dart

@@ -130,19 +130,6 @@ class _MethodLinker extends Visitor<Method, void> {
     final paramLinker = _ParamLinker(typeVisitor);
     node.typeParams.accept(typeParamLinker).toList();
     node.params.accept(paramLinker).toList();
-    // Kotlin specific
-    const kotlinContinutationType = 'kotlin.coroutines.Continuation';
-    if (config.suspendFunToAsync &&
-        node.params.isNotEmpty &&
-        node.params.last.type.kind == Kind.declared &&
-        node.params.last.type.name == kotlinContinutationType) {
-      final continuationType = node.params.last.type.type as DeclaredType;
-      node.asyncReturnType = continuationType.params.isEmpty
-          ? TypeUsage.object
-          : continuationType.params.first;
-    } else {
-      node.asyncReturnType = null;
-    }
     node.asyncReturnType?.accept(typeVisitor);
   }
 }

jnigen/lib/src/config/config_types.dart

@@ -274,7 +274,6 @@ class Config {
     required this.outputConfig,
     required this.classes,
     this.exclude,
-    this.suspendFunToAsync = false,
     this.sourcePath,
     this.classPath,
     this.preamble,
@@ -317,12 +316,6 @@ class Config {
   /// Common text to be pasted on top of generated C and Dart files.
   final String? preamble;
 
-  /// Whether or not to change Kotlin's suspend functions to Dart async ones.
-  ///
-  /// This will remove the final Continuation argument.
-  /// Defaults to [false].
-  final bool suspendFunToAsync;
-
   /// Configuration to search for Android SDK libraries (Experimental).
   final AndroidSdkConfig? androidSdkConfig;
 
@@ -522,7 +515,6 @@ class Config {
         methods: regexFilter<Method>(_Props.excludeMethods),
         fields: regexFilter<Field>(_Props.excludeFields),
       ),
-      suspendFunToAsync: prov.getBool(_Props.suspendFunToAsync) ?? false,
       outputConfig: OutputConfig(
         bindingsType: getBindingsType(
           prov.getString(_Props.bindingsType),
@@ -613,8 +605,6 @@ class _Props {
   static const excludeMethods = '$exclude.methods';
   static const excludeFields = '$exclude.fields';
 
-  static const suspendFunToAsync = 'suspend_fun_to_async';
-
   static const import = 'import';
   static const outputConfig = 'output';
   static const bindingsType = '$outputConfig.bindings_type';

jnigen/lib/src/elements/elements.dart

@@ -478,12 +478,11 @@ class Method extends ClassMember implements Element<Method> {
   @JsonKey(includeFromJson: false)
   late bool isOverridden;
 
-  /// This gets populated in the preprocessing stage.
+  /// The actual return type when the method is a Kotlin's suspend fun.
   ///
-  /// It will contain a type only when the suspendFunToAsync flag is on
-  /// and the method has a `kotlin.coroutines.Continuation` final argument.
+  /// Populated by [KotlinProcessor].
   @JsonKey(includeFromJson: false)
-  late TypeUsage? asyncReturnType;
+  TypeUsage? asyncReturnType;
 
   @JsonKey(includeFromJson: false)
   late String javaSig = '$name$descriptor';

jnigen/lib/src/generate_bindings.dart

@@ -8,6 +8,7 @@ import 'dart:convert';
 import 'bindings/c_generator.dart';
 import 'bindings/dart_generator.dart';
 import 'bindings/excluder.dart';
+import 'bindings/kotlin_processor.dart';
 import 'bindings/linker.dart';
 import 'bindings/unnester.dart';
 import 'bindings/renamer.dart';
@@ -36,6 +37,7 @@ Future<void> generateJniBindings(Config config) async {
   }
 
   classes.accept(Excluder(config));
+  classes.accept(KotlinProcessor());
   await classes.accept(Linker(config));
   classes.accept(Unnester());
   classes.accept(Renamer(config));

jnigen/pubspec.yaml

@@ -3,7 +3,7 @@
 # BSD-style license that can be found in the LICENSE file.
 
 name: jnigen
-version: 0.5.0
+version: 0.6.0-dev.0
 description: Experimental generator for FFI+JNI bindings.
 repository: https://github.com/dart-lang/jnigen/tree/main/jnigen
 

jnigen/test/kotlin_test/generate.dart

@@ -51,7 +51,6 @@ Config getConfig([BindingsType bindingsType = BindingsType.cBased]) {
       // way to the generated code.
       'com.github.dart_lang.jnigen',
     ],
-    suspendFunToAsync: true,
     logLevel: Level.ALL,
     outputConfig: OutputConfig(
       bindingsType: bindingsType,