gradle-plugin: Show error if konan.home-based classpaths are empty

Issue link: https://github.com/JetBrains/kotlin-native/issues/773

GRADLE_PLUGIN.md

@@ -24,10 +24,10 @@ project property:
 
     konan.version=0.3
 
-If you already downloaded the compiler manually you may specify the path to it using `konan.home` project property (e.g.
- in `gradle.properties`). Note: the plugin ignores the `konan.version` property in this case.
+If you already downloaded the compiler manually you may specify the path to its root directory using `konan.home`
+project property (e.g. in `gradle.properties`). Note: the plugin ignores the `konan.version` property in this case.
 
-    konan.home=/path/to/already/downloaded/compiler
+    konan.home=/home/user/kotlin-native-0.3
 
 In this case the compiler will not be downloaded by the plugin.
 

tools/kotlin-native-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KonanCompileTask.kt

@@ -75,8 +75,6 @@ open class KonanCompileTask: KonanTargetableTask() {
 
     val COMPILER_JVM_ARGS: List<String>
         @Internal get() = listOf("-Dkonan.home=${project.konanHome}", "-Djava.library.path=${project.konanHome}/konan/nativelib")
-    val COMPILER_CLASSPATH: String
-        @Internal get() = "${project.konanHome}/konan/lib/"
 
     // Output artifact --------------------------------------------------------
 
@@ -175,7 +173,7 @@ open class KonanCompileTask: KonanTargetableTask() {
         project.javaexec {
             with(it) {
                 main = COMPILER_MAIN
-                classpath = project.fileTree(COMPILER_CLASSPATH).apply { include("*.jar") }
+                classpath = project.konanCompilerClasspath
                 jvmArgs(COMPILER_JVM_ARGS)
                 args(buildArgs().apply { logger.info("Compiler args: ${this.joinToString(separator = " ")}") })
             }

tools/kotlin-native-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KonanCompilerDownloadTask.kt

@@ -35,14 +35,27 @@ open class KonanCompilerDownloadTask : DefaultTask() {
         if (!project.hasProperty(KonanPlugin.ProjectProperty.DOWNLOAD_COMPILER)) {
             val konanHome = project.getProperty(KonanPlugin.ProjectProperty.KONAN_HOME)
             logger.info("Use a user-defined compiler path: $konanHome")
+
+            val interopClasspath = project.konanInteropClasspath
+            if (interopClasspath.isEmpty) {
+                throw IllegalStateException("Stub generator classpath is empty: ${interopClasspath.dir}\n" +
+                        "Probably the 'konan.home' project property contains an incorrect path. Please change it to the compiler root directory and rerun the build.")
+            }
+
+            val compilerClasspath = project.konanCompilerClasspath
+            if (compilerClasspath.isEmpty) {
+                throw IllegalStateException("Kotlin/Native compiler classpath is empty: ${compilerClasspath.dir}\n" +
+                        "Probably the 'konan.home' project property contains an incorrect path. Please change it to the compiler root directory and rerun the build.")
+            }
+
             return
         }
         try {
             val konanCompiler = project.konanCompilerName()
-            logger.info("Downloading Kotlin Native compiler from $DOWNLOAD_URL/$konanCompiler into $KONAN_PARENT_DIR")
+            logger.info("Downloading Kotlin/Native compiler from $DOWNLOAD_URL/$konanCompiler into $KONAN_PARENT_DIR")
             DependencyDownloader(File(KONAN_PARENT_DIR), DOWNLOAD_URL, listOf(konanCompiler)).run()
         } catch (e: RuntimeException) {
-            throw GradleScriptException("Cannot download Kotlin Native compiler", e)
+            throw GradleScriptException("Cannot download Kotlin/Native compiler", e)
         }
     }
 }

tools/kotlin-native-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KonanInteropTask.kt

@@ -56,8 +56,6 @@ open class KonanInteropTask: KonanTargetableTask() {
 
     internal val INTEROP_JVM_ARGS: List<String>
         @Internal get() = listOf("-Dkonan.home=${project.konanHome}", "-Djava.library.path=${project.konanHome}/konan/nativelib")
-    internal val INTEROP_CLASSPATH: String
-        @Internal get() = "${project.konanHome}/konan/lib/"
 
     // Output directories -----------------------------------------------------
 
@@ -100,7 +98,7 @@ open class KonanInteropTask: KonanTargetableTask() {
         project.javaexec {
             with(it) {
                 main = INTEROP_MAIN
-                classpath = project.fileTree(INTEROP_CLASSPATH).apply { include("*.jar") }
+                classpath = project.konanInteropClasspath
                 jvmArgs(INTEROP_JVM_ARGS)
                 environment("LIBCLANG_DISABLE_CRASH_RECOVERY", "1")
                 // TODO: remove this hack.

tools/kotlin-native-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KonanPlugin.kt

@@ -60,6 +60,12 @@ internal val Project.konanDefaultSrcDir           get() = file("${projectDir.can
 internal fun Project.konanDefaultDefFile(interopName: String)
         = file("${projectDir.canonicalPath}/src/main/c_interop/$interopName.def")
 
+internal val Project.konanInteropClasspath
+    get() = project.fileTree("${project.konanHome}/konan/lib/").apply { include("*.jar")  }
+
+internal val Project.konanCompilerClasspath
+    get() = project.fileTree("${project.konanHome}/konan/lib/").apply { include("*.jar")  }
+
 @Suppress("UNCHECKED_CAST")
 internal val Project.konanArtifactsContainer: NamedDomainObjectContainer<KonanCompileConfig>
     get() = extensions.getByName(KonanPlugin.ARTIFACTS_CONTAINER_NAME) as NamedDomainObjectContainer<KonanCompileConfig>

tools/kotlin-native-gradle-plugin/src/test/groovy/org/jetbrains/kotlin/gradle/plugin/test/PathSpecification.groovy

@@ -1,5 +1,6 @@
 package org.jetbrains.kotlin.gradle.plugin.test
 
+import org.gradle.testkit.runner.TaskOutcome
 import org.junit.Rule
 import org.junit.rules.TemporaryFolder
 import spock.lang.Specification
@@ -29,4 +30,24 @@ class PathSpecification extends Specification {
         nativeLib.exists() && nativeLib.file
     }
 
+    def 'Plugin should stop building if the compiler classpath is empty'() {
+        when:
+        def project = KonanProject.createEmpty(tmpFolder)
+        project.propertiesFile.write("konan.home=${tmpFolder.root.canonicalPath}}")
+        def result = project.createRunner().withArguments('build').buildAndFail()
+
+        then:
+        result.task(project.downloadTask).outcome == TaskOutcome.FAILED
+    }
+
+    def 'Plugin should stop building if the stub generator classpath is empty'() {
+        when:
+        def project = KonanInteropProject.createEmpty(tmpFolder)
+        project.propertiesFile.write("konan.home=${tmpFolder.root.canonicalPath}}")
+        def result = project.createRunner().withArguments('build').buildAndFail()
+
+        then:
+        result.task(project.downloadTask).outcome == TaskOutcome.FAILED
+    }
+
 }