add optional annotations artifact

annotations-optional/build.gradle

@@ -0,0 +1,12 @@
+plugins {
+  alias(libs.plugins.kotlin.jvm)
+}
+apply from: rootProject.file('publishing.gradle')
+
+kotlin {
+  explicitApi()
+}
+
+dependencies {
+  api libs.inject
+}

annotations-optional/gradle.properties

@@ -0,0 +1,3 @@
+POM_NAME=Anvil Optional Annotations
+POM_ARTIFACT_ID=annotations-optional
+POM_PACKAGING=jar

annotations-optional/src/main/java/com/squareup/anvil/annotations/optional/ForScope.kt

@@ -0,0 +1,35 @@
+package com.squareup.anvil.annotations.optional
+
+import kotlin.annotation.AnnotationRetention.RUNTIME
+import kotlin.reflect.KClass
+import javax.inject.Qualifier
+
+/**
+ * A class based [qualfier](Qualifier).
+ *
+ * This can be used in combination with other Anvil annotations to avoid having
+ * to manually define qualifier annotations for each component and to maintain 
+ * consistency.
+ *
+ * Example:
+ * ```
+ * interface Authenticator
+ *
+ * @ForScope(AppScope::class)
+ * @ContributesBinding(AppScope::class)
+ * class CommonAuthenticator @Inject constructor() : Authenticator
+ *
+ * @ForScope(UserScope::class)
+ * @ContributesBinding(UserScope::class)
+ * class UserAuthenticator @Inject constructor() : Authenticator
+ * ```
+ */
+@Qualifier
+@Retention(RUNTIME)
+public annotation class ForScope(
+  /**
+   * The marker that identifies the component in which the annotated object is
+   * provided or bound in.
+   */
+  val scope: KClass<*>,
+)

annotations-optional/src/main/java/com/squareup/anvil/annotations/optional/SingleIn.kt

@@ -0,0 +1,40 @@
+package com.squareup.anvil.annotations.optional
+
+import kotlin.annotation.AnnotationRetention.RUNTIME
+import kotlin.reflect.KClass
+import javax.inject.Scope
+
+/**
+ * Identifies a type that the injector only instantiates once for the given
+ * [scope] marker. 
+ *
+ * This can be used in combination with other Anvil annotations to avoid having
+ * to manually define scope annotations for each component and to maintain 
+ * consistency.
+ *
+ * Component example:
+ * ```
+ * @SingleIn(AppScope::class)
+ * @MergeComponent(AppScope::class)
+ * interface AppComponent
+ * ```
+ *
+ * Contribution example:
+ * ```
+ * interface Authenticator
+ *
+ * @SingleIn(AppScope::class)
+ * @ContributesBinding(AppScope::class)
+ * class RealAuthenticator @Inject constructor() : Authenticator
+ * ```
+ *
+ * See Also: [@Scope](Scope)
+ */
+@Scope
+@Retention(RUNTIME)
+public annotation class SingleIn(
+  /**
+   * The marker that identifies this scope.
+   */
+  val scope: KClass<*>,
+)

settings.gradle

@@ -39,6 +39,7 @@ dependencyResolutionManagement {
 }
 
 include ':annotations'
+include ':annotations-optional'
 include ':compiler'
 include ':compiler-api'
 include ':compiler-utils'