Implement automatic loading of .main.kts scripts support

also fix discovery from ScriptDefinitionsProvider

compiler/util/src/org/jetbrains/kotlin/utils/KotlinPaths.kt

@@ -100,13 +100,15 @@ interface KotlinPaths {
         CoroutinesCore(PathUtil.KOTLINX_COROUTINES_CORE_NAME),
         KotlinDaemon(PathUtil.KOTLIN_DAEMON_NAME),
         Ktor(PathUtil.KTOR_NAME),
+        MainKts(PathUtil.MAIN_KTS_NAME)
     }
 
     // TODO: Maybe we need separate classpaths for compilers with and without the daemon
     enum class ClassPaths(val contents: List<Jar> = emptyList()) {
         Empty(),
         Compiler(Jar.Compiler, Jar.StdLib, Jar.Reflect, Jar.ScriptRuntime, Jar.Trove4j, Jar.KotlinDaemon, Jar.Ktor),
-        CompilerWithScripting(Compiler, Jar.ScriptingPlugin, Jar.ScriptingImpl, Jar.ScriptingLib, Jar.ScriptingJvmLib)
+        CompilerWithScripting(Compiler, Jar.ScriptingPlugin, Jar.ScriptingImpl, Jar.ScriptingLib, Jar.ScriptingJvmLib),
+        MainKts(Jar.MainKts, Jar.ScriptRuntime, Jar.StdLib, Jar.Reflect)
         ;
 
         constructor(vararg jars: Jar) : this(jars.asList())

compiler/util/src/org/jetbrains/kotlin/utils/PathUtil.kt

@@ -79,6 +79,7 @@ object PathUtil {
     const val KOTLIN_SCRIPTING_COMPILER_IMPL_JAR = "$KOTLIN_SCRIPTING_COMPILER_IMPL_NAME.jar"
     const val JS_ENGINES_NAME = "js.engines"
     const val JS_ENGINES_JAR = "$JS_ENGINES_NAME.jar"
+    const val MAIN_KTS_NAME = "kotlin-main-kts"
 
     val KOTLIN_SCRIPTING_PLUGIN_CLASSPATH_JARS = arrayOf(
         KOTLIN_SCRIPTING_COMPILER_PLUGIN_JAR, KOTLIN_SCRIPTING_COMPILER_IMPL_JAR,

idea/resources/META-INF/extensions/ide.xml

@@ -92,6 +92,9 @@
         <scriptDefinitionContributor id="ConsoleScriptDefinitionContributor"
                                      implementation="org.jetbrains.kotlin.console.ConsoleScriptDefinitionContributor"/>
 
+        <scriptDefinitionsProvider id="MainKtsScriptDefinitionSource"
+                                   implementation="org.jetbrains.kotlin.idea.script.MainKtsScriptDefinitionSource"/>
+
         <idePlatformKindResolution implementation="org.jetbrains.kotlin.caches.resolve.JvmPlatformKindResolution"/>
         <idePlatformKindResolution implementation="org.jetbrains.kotlin.caches.resolve.JsPlatformKindResolution"/>
         <idePlatformKindResolution implementation="org.jetbrains.kotlin.caches.resolve.CommonPlatformKindResolution"/>

idea/src/org/jetbrains/kotlin/idea/script/BridgeDefinitionsContributor.kt

@@ -30,12 +30,13 @@ class BridgeScriptDefinitionsContributor(private val project: Project) : ScriptD
                     if (explicitClasses.isEmpty()) emptySequence()
                     else loadDefinitionsFromTemplates(explicitClasses, classPath, hostConfiguration).asSequence()
                 val discoveredDefinitions =
-                    if (provider.useDiscovery()) emptySequence()
-                    else ScriptDefinitionsFromClasspathDiscoverySource(
-                        classPath,
-                        hostConfiguration,
-                        ::loggingReporter
-                    ).definitions
+                    if (provider.useDiscovery())
+                        ScriptDefinitionsFromClasspathDiscoverySource(
+                            classPath,
+                            hostConfiguration,
+                            ::loggingReporter
+                        ).definitions
+                    else emptySequence()
                 explicitDefinitions + discoveredDefinitions
             }
         }

idea/src/org/jetbrains/kotlin/idea/script/MainKtsScriptDefinitionSource.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2010-2020 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.script
+
+import com.intellij.openapi.diagnostic.Logger
+import org.jetbrains.kotlin.utils.KotlinPaths
+import org.jetbrains.kotlin.utils.PathUtil
+import java.io.File
+import kotlin.script.experimental.intellij.ScriptDefinitionsProvider
+
+class MainKtsScriptDefinitionSource : ScriptDefinitionsProvider {
+    override val id: String = ".main.kts script"
+
+    override fun getDefinitionClasses(): Iterable<String> = emptyList()
+
+    override fun getDefinitionsClassPath(): Iterable<File> {
+
+        val paths = PathUtil.kotlinPathsForIdeaPlugin
+        return if (paths.jar(KotlinPaths.Jar.MainKts).exists()) {
+            paths.classPath(KotlinPaths.ClassPaths.MainKts)
+        } else {
+            Logger.getInstance(MainKtsScriptDefinitionSource::class.java).warn("[kts] Support for .main.kts scripts is not loaded: kotlin-main-kts.jar not found")
+            emptyList()
+        }
+    }
+
+    override fun useDiscovery(): Boolean = true
+}