use Extension to control the targets container, so that Gradle will generate Kotlin DSL accessors

README.md

@@ -131,7 +131,7 @@ binaryCompatibilityValidator {
   }
 
   // BCV will automatically register a target for testFixtures, but it must be enabled manually
-  targets.named("testFixtures") {
+  targets.testFixtures {
     enabled.set(true)
   }
 

modules/bcv-gradle-plugin-functional-tests/src/functionalTest/kotlin/kotlinx/validation/test/JavaTestFixturesTest.kt

@@ -130,7 +130,7 @@ private fun FunSpec.createTestFixturesProject(
         |}
         |
         |binaryCompatibilityValidator {
-        |  testFixtures {
+        |  targets.testFixtures {
         |    enabled.set($bcvTestFixturesTargetEnabled)
         |  }
         |}

modules/bcv-gradle-plugin-functional-tests/src/functionalTest/resources/examples/gradle/configuration/jarAsInput/inputJar.gradle.kts

@@ -4,7 +4,7 @@ tasks.jar {
 }
 
 binaryCompatibilityValidator {
-  kotlinJvm {
+  targets.kotlinJvm {
     inputJar.set(tasks.jar.flatMap { it.archiveFile })
   }
 }

modules/bcv-gradle-plugin/api/bcv-gradle-plugin.api

@@ -11,7 +11,7 @@ public abstract class dev/adamko/kotlin/binary_compatibility_validator/BCVPlugin
 public final class dev/adamko/kotlin/binary_compatibility_validator/BCVPlugin$Companion {
 }
 
-public abstract interface class dev/adamko/kotlin/binary_compatibility_validator/BCVProjectExtension : dev/adamko/kotlin/binary_compatibility_validator/targets/BCVTargetSpec, org/gradle/api/plugins/ExtensionAware {
+public abstract class dev/adamko/kotlin/binary_compatibility_validator/BCVProjectExtension : dev/adamko/kotlin/binary_compatibility_validator/targets/BCVTargetSpec, org/gradle/api/plugins/ExtensionAware {
 	public abstract fun getEnabled ()Lorg/gradle/api/provider/Property;
 	public abstract fun getIgnoredClasses ()Lorg/gradle/api/provider/SetProperty;
 	public abstract fun getIgnoredMarkers ()Lorg/gradle/api/provider/SetProperty;
@@ -23,7 +23,7 @@ public abstract interface class dev/adamko/kotlin/binary_compatibility_validator
 	public abstract fun getPublicClasses ()Lorg/gradle/api/provider/SetProperty;
 	public abstract fun getPublicMarkers ()Lorg/gradle/api/provider/SetProperty;
 	public abstract fun getPublicPackages ()Lorg/gradle/api/provider/SetProperty;
-	public abstract fun getTargets ()Lorg/gradle/api/NamedDomainObjectContainer;
+	public final fun getTargets ()Lorg/gradle/api/NamedDomainObjectContainer;
 }
 
 public abstract class dev/adamko/kotlin/binary_compatibility_validator/BCVProjectPlugin : org/gradle/api/Plugin {
@@ -94,7 +94,7 @@ public abstract class dev/adamko/kotlin/binary_compatibility_validator/tasks/BCV
 	public abstract fun getOutputApiBuildDir ()Lorg/gradle/api/file/DirectoryProperty;
 	public abstract fun getProjectName ()Lorg/gradle/api/provider/Property;
 	public abstract fun getRuntimeClasspath ()Lorg/gradle/api/file/ConfigurableFileCollection;
-	public abstract fun getTargets ()Lorg/gradle/api/NamedDomainObjectContainer;
+	public final fun getTargets ()Lorg/gradle/api/NamedDomainObjectContainer;
 }
 
 public abstract class dev/adamko/kotlin/binary_compatibility_validator/tasks/BCVDefaultTask : org/gradle/api/DefaultTask {

modules/bcv-gradle-plugin/src/main/kotlin/BCVProjectExtension.kt

@@ -1,51 +1,62 @@
 package dev.adamko.kotlin.binary_compatibility_validator
 
+import dev.adamko.kotlin.binary_compatibility_validator.internal.BCVInternalApi
+import dev.adamko.kotlin.binary_compatibility_validator.internal.adding
+import dev.adamko.kotlin.binary_compatibility_validator.internal.domainObjectContainer
 import dev.adamko.kotlin.binary_compatibility_validator.targets.BCVTarget
 import dev.adamko.kotlin.binary_compatibility_validator.targets.BCVTargetSpec
+import javax.inject.Inject
 import org.gradle.api.NamedDomainObjectContainer
 import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.model.ObjectFactory
 import org.gradle.api.model.ReplacedBy
 import org.gradle.api.plugins.ExtensionAware
 import org.gradle.api.provider.Property
 import org.gradle.api.provider.SetProperty
 
-interface BCVProjectExtension : BCVTargetSpec, ExtensionAware {
+abstract class BCVProjectExtension
+@BCVInternalApi
+@Inject
+constructor(
+  private val objects: ObjectFactory
+) : BCVTargetSpec, ExtensionAware {
 
   /** Sets the default [BCVTarget.enabled] value for all [targets]. */
-  override val enabled: Property<Boolean>
+  abstract override val enabled: Property<Boolean>
 
   /** Sets the default [BCVTarget.ignoredPackages] value for all [targets]. */
-  override val ignoredPackages: SetProperty<String>
+  abstract override val ignoredPackages: SetProperty<String>
 
   /** Sets the default [BCVTarget.publicMarkers] for all [targets] */
-  override val publicMarkers: SetProperty<String>
+  abstract override val publicMarkers: SetProperty<String>
 
   /** Sets the default [BCVTarget.publicPackages] for all [targets] */
-  override val publicPackages: SetProperty<String>
+  abstract override val publicPackages: SetProperty<String>
 
   /** Sets the default [BCVTarget.publicClasses] for all [targets] */
-  override val publicClasses: SetProperty<String>
+  abstract override val publicClasses: SetProperty<String>
 
   /** Sets the default [BCVTarget.ignoredMarkers] value for all [targets]. */
-  override val ignoredMarkers: SetProperty<String>
+  abstract override val ignoredMarkers: SetProperty<String>
 
   @get:ReplacedBy("ignoredMarkers")
   @Deprecated("renamed to ignoredMarkers", ReplaceWith("ignoredMarkers"))
-  val nonPublicMarkers: SetProperty<String>
+  abstract val nonPublicMarkers: SetProperty<String>
 
   /** Sets the default [BCVTarget.ignoredClasses] value for all [targets]. */
-  override val ignoredClasses: SetProperty<String>
+  abstract override val ignoredClasses: SetProperty<String>
 
   /**
    * The directory that contains the API declarations.
    *
    * Defaults to [BCVPlugin.API_DIR].
    */
-  val outputApiDir: DirectoryProperty
+  abstract val outputApiDir: DirectoryProperty
 
-  val projectName: Property<String>
+  abstract val projectName: Property<String>
 
-  val kotlinxBinaryCompatibilityValidatorVersion: Property<String>
+  abstract val kotlinxBinaryCompatibilityValidatorVersion: Property<String>
 
-  val targets: NamedDomainObjectContainer<BCVTarget>
+  val targets: NamedDomainObjectContainer<BCVTarget> =
+    extensions.adding("targets") { objects.domainObjectContainer() }
 }

modules/bcv-gradle-plugin/src/main/kotlin/BCVProjectPlugin.kt

@@ -119,10 +119,6 @@ constructor(
       ignoredPackages.convention(extension.ignoredPackages)
     }
 
-    extension.targets.all {
-      extension.extensions.add(platformType, this)
-    }
-
     return extension
   }
 

modules/bcv-gradle-plugin/src/main/kotlin/internal/gradleUtils.kt

@@ -0,0 +1,48 @@
+package dev.adamko.kotlin.binary_compatibility_validator.internal
+
+import org.gradle.api.NamedDomainObjectContainer
+import org.gradle.api.NamedDomainObjectFactory
+import org.gradle.api.model.ObjectFactory
+import org.gradle.api.plugins.ExtensionContainer
+import org.gradle.kotlin.dsl.*
+
+
+/**
+ * Create a new [NamedDomainObjectContainer], using
+ * [org.gradle.kotlin.dsl.domainObjectContainer]
+ * (but [T] is `reified`).
+ *
+ * @param[factory] an optional factory for creating elements
+ * @see org.gradle.kotlin.dsl.domainObjectContainer
+ */
+internal inline fun <reified T : Any> ObjectFactory.domainObjectContainer(
+  factory: NamedDomainObjectFactory<T>? = null
+): NamedDomainObjectContainer<T> =
+  if (factory == null) {
+    domainObjectContainer(T::class)
+  } else {
+    domainObjectContainer(T::class, factory)
+  }
+
+
+/**
+ * [Add][ExtensionContainer.add] a value (from [valueProvider]) with [name], and return the value.
+ *
+ * Adding an extension is especially useful for improving the DSL in build scripts when [T] is a
+ * [NamedDomainObjectContainer].
+ * Using an extension will allow Gradle to generate
+ * [type-safe model accessors](https://docs.gradle.org/current/userguide/kotlin_dsl.html#kotdsl:accessor_applicability)
+ * for added types.
+ *
+ * ([name] should match the property name. This has to be done manually because using a
+ * delegated-property provider means Gradle can't introspect the types properly, so it fails to
+ * create accessors).
+ */
+internal inline fun <reified T : Any> ExtensionContainer.adding(
+  name: String,
+  crossinline valueProvider: () -> T,
+): T {
+  val value: T = valueProvider()
+  add<T>(name, value)
+  return value
+}

modules/bcv-gradle-plugin/src/main/kotlin/tasks/BCVApiGenerateTask.kt

@@ -1,13 +1,16 @@
 package dev.adamko.kotlin.binary_compatibility_validator.tasks
 
 import dev.adamko.kotlin.binary_compatibility_validator.internal.BCVInternalApi
+import dev.adamko.kotlin.binary_compatibility_validator.internal.adding
+import dev.adamko.kotlin.binary_compatibility_validator.internal.domainObjectContainer
 import dev.adamko.kotlin.binary_compatibility_validator.targets.BCVTarget
 import dev.adamko.kotlin.binary_compatibility_validator.workers.BCVSignaturesWorker
 import java.io.*
 import javax.inject.Inject
 import kotlinx.validation.api.*
 import org.gradle.api.*
 import org.gradle.api.file.*
+import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.*
 import org.gradle.kotlin.dsl.*
@@ -21,10 +24,12 @@ abstract class BCVApiGenerateTask
 constructor(
   private val workers: WorkerExecutor,
   private val fs: FileSystemOperations,
+  private val objects: ObjectFactory,
 ) : BCVDefaultTask() {
 
   @get:Nested
-  abstract val targets: NamedDomainObjectContainer<BCVTarget>
+  val targets: NamedDomainObjectContainer<BCVTarget> =
+    extensions.adding("targets") { objects.domainObjectContainer() }
 
   @get:InputFiles
   @get:PathSensitive(PathSensitivity.RELATIVE)