IDE: add warn on java files outside java source roots

#KT-28121 Fixed

idea/idea-jvm/src/org/jetbrains/kotlin/idea/inspections/JavaOutsideModuleDetector.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2010-2019 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.
+ */
+
+package org.jetbrains.kotlin.idea.inspections
+
+import com.intellij.ide.highlighter.JavaFileType
+import com.intellij.openapi.fileEditor.FileEditor
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.util.Key
+import com.intellij.openapi.vfs.VirtualFile
+import com.intellij.ui.EditorNotificationPanel
+import com.intellij.ui.EditorNotifications
+import org.jetbrains.kotlin.idea.facet.KotlinFacet
+import org.jetbrains.kotlin.idea.framework.isGradleModule
+import org.jetbrains.kotlin.idea.util.findModule
+import org.jetbrains.kotlin.idea.util.sourceRoots
+
+class JavaOutsideModuleDetector(private val project: Project) : EditorNotifications.Provider<EditorNotificationPanel>() {
+    override fun getKey(): Key<EditorNotificationPanel> = KEY
+
+    override fun createNotificationPanel(file: VirtualFile, fileEditor: FileEditor): EditorNotificationPanel? {
+        if (file.fileType != JavaFileType.INSTANCE) return null
+        val module = file.findModule(project) ?: return null
+        if (!module.isGradleModule()) return null
+        val facetSettings = KotlinFacet.get(module)?.configuration?.settings ?: return null
+
+        val filePath = file.path
+        val nonKotlinPath = module.sourceRoots.map { it.path } - facetSettings.pureKotlinSourceFolders
+        if (nonKotlinPath.any { filePath.startsWith(it) }) return null
+        return EditorNotificationPanel().apply {
+            setText("This .java file is outside of Java source roots and won't be added to the class-path.")
+        }
+    }
+
+    companion object {
+        private val KEY = Key.create<EditorNotificationPanel>("JavaOutsideModuleDetector")
+    }
+}

idea/resources/META-INF/jvm.xml

@@ -129,6 +129,7 @@
 
         <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.configuration.KotlinSetupEnvironmentNotificationProvider"/>
         <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.debugger.KotlinAlternativeSourceNotificationProvider"/>
+        <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.inspections.JavaOutsideModuleDetector"/>
 
         <consoleFilterProvider implementation="org.jetbrains.kotlin.idea.run.KotlinConsoleFilterProvider"/>
 

idea/resources/META-INF/jvm.xml.182

@@ -128,6 +128,7 @@
 
         <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.configuration.KotlinSetupEnvironmentNotificationProvider"/>
         <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.debugger.KotlinAlternativeSourceNotificationProvider"/>
+        <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.inspections.JavaOutsideModuleDetector"/>
 
         <consoleFilterProvider implementation="org.jetbrains.kotlin.idea.run.KotlinConsoleFilterProvider"/>
 

idea/resources/META-INF/jvm.xml.183

@@ -129,6 +129,7 @@
 
         <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.configuration.KotlinSetupEnvironmentNotificationProvider"/>
         <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.debugger.KotlinAlternativeSourceNotificationProvider"/>
+        <editorNotificationProvider implementation="org.jetbrains.kotlin.idea.inspections.JavaOutsideModuleDetector"/>
 
         <consoleFilterProvider implementation="org.jetbrains.kotlin.idea.run.KotlinConsoleFilterProvider"/>