From 73b18ba2cdc5144c87d5757423d78b834051f8f8 Mon Sep 17 00:00:00 2001
From: Ralf Wondratschek <rwo@amazon.com>
Date: Fri, 15 Nov 2024 10:36:27 -0800
Subject: [PATCH] Copy required annotations to generated code

Copy all annotations from `expect fun` functions annotated with `@CreateComponent` to the generated `actual fun` functions to avoid a Kotlin compiler warning.

Fixes #72
---
 .../kotlin/inject/anvil/gradle/KotlinPlugin.kt      | 10 +++++++---
 .../anvil/processor/CreateComponentProcessor.kt     | 13 +++++++++++--
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/build-logic/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/gradle/KotlinPlugin.kt b/build-logic/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/gradle/KotlinPlugin.kt
index e99e475..3870c2f 100644
--- a/build-logic/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/gradle/KotlinPlugin.kt
+++ b/build-logic/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/gradle/KotlinPlugin.kt
@@ -12,6 +12,7 @@ import org.gradle.api.tasks.SourceTask
 import org.gradle.api.tasks.compile.JavaCompile
 import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask
 import org.jetbrains.kotlin.gradle.tasks.KotlinJvmCompile
 import org.jlleitschuh.gradle.ktlint.KtlintExtension
 import java.io.File
@@ -33,9 +34,12 @@ internal open class KotlinPlugin : Plugin<Project> {
     }
 
     private fun Project.configureKotlinCompile() {
-        tasks.withType(KotlinJvmCompile::class.java).configureEach {
-            it.compilerOptions.jvmTarget.set(JvmTarget.fromTarget(javaVersion.toString()))
-            it.compilerOptions.allWarningsAsErrors.set(ci)
+        tasks.withType(KotlinCompilationTask::class.java).configureEach {
+            // TODO: ci
+            it.compilerOptions.allWarningsAsErrors.set(true)
+            if (it is KotlinJvmCompile) {
+                it.compilerOptions.jvmTarget.set(JvmTarget.fromTarget(javaVersion.toString()))
+            }
         }
     }
 
diff --git a/compiler/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/processor/CreateComponentProcessor.kt b/compiler/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/processor/CreateComponentProcessor.kt
index 047e3ec..e22a77a 100644
--- a/compiler/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/processor/CreateComponentProcessor.kt
+++ b/compiler/src/main/kotlin/software/amazon/lastmile/kotlin/inject/anvil/processor/CreateComponentProcessor.kt
@@ -19,6 +19,7 @@ import com.squareup.kotlinpoet.KModifier.ACTUAL
 import com.squareup.kotlinpoet.ParameterSpec
 import com.squareup.kotlinpoet.ParameterizedTypeName.Companion.parameterizedBy
 import com.squareup.kotlinpoet.asTypeName
+import com.squareup.kotlinpoet.ksp.toAnnotationSpec
 import com.squareup.kotlinpoet.ksp.toClassName
 import com.squareup.kotlinpoet.ksp.toTypeName
 import com.squareup.kotlinpoet.ksp.writeTo
@@ -61,6 +62,15 @@ internal class CreateComponentProcessor(
         resolver
             .getSymbolsWithAnnotation(MergeComponent.CreateComponent::class)
             .filterIsInstance<KSFunctionDeclaration>()
+            .filter {
+                // We copy all annotations from the expect function, including @CreateComponent,
+                // to the actual functions. Without doing so the Kotlin compiler would print a
+                // warning.
+                //
+                // Without this filter we'd try to process the generated actual function, which
+                // leads to errors.
+                Modifier.ACTUAL !in it.modifiers
+            }
             .onEach { function ->
                 checkIsPublic(function) {
                     "Factory functions for components annotated with `@CreateComponent` must be public."
@@ -82,8 +92,6 @@ internal class CreateComponentProcessor(
             .toClassName()
         val generatedComponent = component.peerClass("KotlinInject${component.simpleName}")
 
-        function.requireContainingFile()
-
         val parametersAsSpec = function.parameters.map {
             ParameterSpec
                 .builder(
@@ -109,6 +117,7 @@ internal class CreateComponentProcessor(
                             )
                         }
                     }
+                    .addAnnotations(function.annotations.map { it.toAnnotationSpec() }.toList())
                     .addModifiers(ACTUAL)
                     .addParameters(parametersAsSpec)
                     .returns(component)