[Gradle] Implement AndroidGradlePluginIsMissing diagnostics

^KT-60693 Verification Pending

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/diagnostics/KotlinToolingDiagnostics.kt

@@ -237,6 +237,27 @@ object KotlinToolingDiagnostics {
         )
     }
 
+    object AndroidGradlePluginIsMissing : ToolingDiagnosticFactory(FATAL) {
+        operator fun invoke(trace: Throwable? = null) = build(
+            """
+                The Android target requires a 'Android Gradle Plugin' to be applied to the project. 
+                
+                plugins {
+                    kotlin("multiplatform")
+                    
+                    /* Android Gradle Plugin missing */
+                    id("com.android.library") /* <- Android Gradle Plugin for libraries */
+                    id("com.android.application") <* <- Android Gradle Plugin for applications */
+                }
+                
+                kotlin {
+                    androidTarget() /* <- requires Android Gradle Plugin to be applied */
+                }
+            """.trimIndent(),
+            throwable = trace
+        )
+    }
+
     object NoKotlinTargetsDeclared : ToolingDiagnosticFactory(ERROR) {
         operator fun invoke(projectName: String, projectPath: String) = build(
             """

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/android/KotlinAndroidTargetPreset.kt

@@ -9,6 +9,10 @@ package org.jetbrains.kotlin.gradle.plugin.mpp
 import org.gradle.api.Project
 import org.jetbrains.kotlin.gradle.plugin.KotlinAndroidPlugin.Companion.dynamicallyApplyWhenAndroidPluginIsApplied
 import org.jetbrains.kotlin.gradle.plugin.KotlinTargetPreset
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinToolingDiagnostics
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.KotlinToolingDiagnostics.AndroidGradlePluginIsMissing
+import org.jetbrains.kotlin.gradle.plugin.diagnostics.reportDiagnostic
+import org.jetbrains.kotlin.gradle.utils.findAppliedAndroidPluginIdOrNull
 
 import javax.inject.Inject
 
@@ -19,25 +23,23 @@ abstract class KotlinAndroidTargetPreset @Inject constructor(
     override fun getName(): String = PRESET_NAME
 
     override fun createTarget(name: String): KotlinAndroidTarget {
-        val result = project.objects.newInstance(
+
-            KotlinAndroidTarget::class.java,
+        /*
-            name,
+        Android Gradle Plugin is required:
-            project
+        Creating target will fail with Linkage Error instead
-        ).apply {
+
+        Could not create an instance of type org.jetbrains.kotlin.gradle.plugin.mpp.KotlinAndroidTarget.
+            > Could not generate a decorated class for type KotlinAndroidTarget.
+            > com/android/build/gradle/api/BaseVariant
+         */
+        project.findAppliedAndroidPluginIdOrNull() ?: project.reportDiagnostic(AndroidGradlePluginIsMissing(Throwable()))
+
+        return project.objects.newInstance(KotlinAndroidTarget::class.java, name, project).apply {
             preset = this@KotlinAndroidTargetPreset
-            targetUnderConstruction = this
+            project.dynamicallyApplyWhenAndroidPluginIsApplied({ this })
         }
-
-        project.dynamicallyApplyWhenAndroidPluginIsApplied({ result })
-
-        targetUnderConstruction = null
-
-        return result
     }
 
-    /** This is a way to check if there's an Android target being configured now despite it not being added to the `kotlin.targets` yet */
-    internal var targetUnderConstruction: KotlinAndroidTarget? = null
-
     companion object {
         const val PRESET_NAME = "android"
     }

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/unitTests/diagnosticsTests/AndroidGradlePluginIsMissingTest.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("FunctionName")
+
+package org.jetbrains.kotlin.gradle.unitTests.diagnosticsTests
+
+import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
+import org.jetbrains.kotlin.gradle.util.*
+import kotlin.test.Test
+import kotlin.test.assertFails
+
+class AndroidGradlePluginIsMissingTest {
+    @Test
+    fun `test - android plugin is not applied`() {
+        val project = buildProjectWithMPP()
+        assertFails { project.multiplatformExtension.androidTarget() }
+        project.checkDiagnostics("AndroidGradlePluginIsMissing")
+    }
+
+    @Test
+    fun `test - android application plugin is applied`() {
+        val project = buildProjectWithMPP()
+        project.androidApplication { compileSdk = 33 }
+        project.multiplatformExtension.androidTarget()
+        project.assertNoDiagnostics()
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/unitTests/diagnosticsTests/KotlinSourceSetTreeDependsOnMismatchTest.kt

@@ -18,9 +18,9 @@ class KotlinSourceSetTreeDependsOnMismatchTest {
     private fun checkDiagnostics(configure: KotlinMultiplatformExtension.() -> Unit): List<ToolingDiagnostic> {
         val project = buildProjectWithMPP {
             kotlin {
+                project.androidApplication { compileSdk = 32 }
                 applyDefaultHierarchyTemplate()
                 androidTarget()
-                project.androidApplication { compileSdk = 32 }
                 iosX64(); iosArm64(); iosSimulatorArm64()
                 macosX64(); macosArm64()
 

libraries/tools/kotlin-gradle-plugin/src/functionalTest/resources/expectedDiagnostics/AndroidGradlePluginIsMissing.txt

@@ -0,0 +1,13 @@
+[AndroidGradlePluginIsMissing | FATAL] The Android target requires a 'Android Gradle Plugin' to be applied to the project.
+
+plugins {
+    kotlin("multiplatform")
+
+    /* Android Gradle Plugin missing */
+    id("com.android.library") /* <- Android Gradle Plugin for libraries */
+    id("com.android.application") <* <- Android Gradle Plugin for applications */
+}
+
+kotlin {
+    androidTarget() /* <- requires Android Gradle Plugin to be applied */
+}