Fix error when KSP plugin applied before AGP

gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/AndroidPluginIntegration.kt

@@ -39,14 +39,10 @@ import java.util.concurrent.Callable
 @Suppress("UnstableApiUsage") // some android APIs are unsable.
 object AndroidPluginIntegration {
 
-    private val agpPluginIds = listOf("com.android.application", "com.android.library", "com.android.dynamic-feature")
-
     fun forEachAndroidSourceSet(project: Project, onSourceSet: (String) -> Unit) {
-        agpPluginIds.forEach { agpPluginId ->
-            project.pluginManager.withPlugin(agpPluginId) {
-                // for android apps, we need a configuration per source set
-                decorateAndroidExtension(project, onSourceSet)
-            }
+        project.pluginManager.withPlugin("com.android.base") {
+            // for android modules, we need a configuration per source set
+            decorateAndroidExtension(project, onSourceSet)
         }
     }
 

gradle-plugin/src/test/kotlin/com/google/devtools/ksp/gradle/GradleCompilationTest.kt

@@ -414,4 +414,16 @@ class GradleCompilationTest {
         )
         testRule.runner().withArguments(":app:assembleDebug").build()
     }
+
+    /**
+     * Regression test for https://github.com/google/ksp/issues/2174
+     */
+    @Test
+    fun androidGradlePluginBuiltInKotlinWithKspAppliedFirst() {
+        testRule.setupAppAsAndroidApp(applyKspPluginFirst = true)
+        // Enable AGP's built-in Kotlin support for test fixtures
+        testRule.runner()
+            .withArguments("tasks", "-Pandroid.experimental.enableTestFixturesKotlinSupport=true")
+            .build()
+    }
 }

gradle-plugin/src/test/kotlin/com/google/devtools/ksp/gradle/testing/KspIntegrationTestRule.kt

@@ -93,14 +93,25 @@ class KspIntegrationTestRule(
     /**
      * Sets up the app module as an android app, adding necessary plugin dependencies, a manifest
      * file and necessary gradle configuration. If [enableAgpBuiltInKotlinSupport] is true, enable AGP's built-in Kotlin
-     * support instead of applying the Kotlin Android Gradle plugin.
+     * support instead of applying the Kotlin Android Gradle plugin. If [applyKspPluginFirst] is true, apply the KSP
+     * plugin first.
      */
-    fun setupAppAsAndroidApp(enableAgpBuiltInKotlinSupport: Boolean = false) {
+    fun setupAppAsAndroidApp(
+        enableAgpBuiltInKotlinSupport: Boolean = false,
+        applyKspPluginFirst: Boolean = false
+    ) {
         testProject.appModule.plugins.addAll(
-            listOf(
-                PluginDeclaration.id("com.android.application", testConfig.androidBaseVersion),
-                PluginDeclaration.id("com.google.devtools.ksp", testConfig.kspVersion)
-            )
+            if (applyKspPluginFirst) {
+                listOf(
+                    PluginDeclaration.id("com.google.devtools.ksp", testConfig.kspVersion),
+                    PluginDeclaration.id("com.android.application", testConfig.androidBaseVersion)
+                )
+            } else {
+                listOf(
+                    PluginDeclaration.id("com.android.application", testConfig.androidBaseVersion),
+                    PluginDeclaration.id("com.google.devtools.ksp", testConfig.kspVersion)
+                )
+            }
         )
         if (enableAgpBuiltInKotlinSupport) {
             testProject.appModule