Check language feature support for local and top-level lateinit vars

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt

@@ -91,14 +91,17 @@ object ModifierCheckerCore {
     )
 
     private val featureDependencies = mapOf(
-            SUSPEND_KEYWORD   to LanguageFeature.Coroutines,
+            SUSPEND_KEYWORD   to listOf(LanguageFeature.Coroutines),
-            INLINE_KEYWORD    to LanguageFeature.InlineProperties,
+            INLINE_KEYWORD    to listOf(LanguageFeature.InlineProperties),
-            HEADER_KEYWORD    to LanguageFeature.MultiPlatformProjects,
+            HEADER_KEYWORD    to listOf(LanguageFeature.MultiPlatformProjects),
-            IMPL_KEYWORD      to LanguageFeature.MultiPlatformProjects
+            IMPL_KEYWORD      to listOf(LanguageFeature.MultiPlatformProjects),
+            LATEINIT_KEYWORD  to listOf(LanguageFeature.LateinitTopLevelProperties, LanguageFeature.LateinitLocalVariables)
     )
 
     private val featureDependenciesTargets = mapOf(
-            LanguageFeature.InlineProperties to setOf(PROPERTY, PROPERTY_GETTER, PROPERTY_SETTER)
+            LanguageFeature.InlineProperties to setOf(PROPERTY, PROPERTY_GETTER, PROPERTY_SETTER),
+            LanguageFeature.LateinitLocalVariables to setOf(LOCAL_VARIABLE),
+            LanguageFeature.LateinitTopLevelProperties to setOf(TOP_LEVEL_PROPERTY)
     )
 
     // NOTE: deprecated targets must be possible!
@@ -272,28 +275,29 @@ object ModifierCheckerCore {
     ): Boolean {
         val modifier = node.elementType as KtModifierKeywordToken
 
-        val dependency = featureDependencies[modifier] ?: return true
+        val dependencies = featureDependencies[modifier] ?: return true
+        for (dependency in dependencies) {
+            val featureSupport = languageVersionSettings.getFeatureSupport(dependency)
 
-        val featureSupport = languageVersionSettings.getFeatureSupport(dependency)
+            val diagnosticData = dependency to languageVersionSettings
+            if (featureSupport == LanguageFeature.State.ENABLED_WITH_ERROR || featureSupport == LanguageFeature.State.DISABLED) {
+                val restrictedTargets = featureDependenciesTargets[dependency]
+                if (restrictedTargets != null && actualTargets.intersect(restrictedTargets).isEmpty()) {
+                    continue
+                }
 
-        val diagnosticData = dependency to languageVersionSettings
+                if (featureSupport == LanguageFeature.State.DISABLED) {
-        if (featureSupport == LanguageFeature.State.ENABLED_WITH_ERROR || featureSupport == LanguageFeature.State.DISABLED) {
+                    trace.report(Errors.UNSUPPORTED_FEATURE.on(node.psi, diagnosticData))
-            val restrictedTargets = featureDependenciesTargets[dependency]
+                }
-            if (restrictedTargets != null && actualTargets.intersect(restrictedTargets).isEmpty()) {
+                else {
-                return true
+                    trace.report(Errors.EXPERIMENTAL_FEATURE_ERROR.on(node.psi, diagnosticData))
+                }
+                return false
             }
 
-            if (featureSupport == LanguageFeature.State.DISABLED) {
+            if (featureSupport == LanguageFeature.State.ENABLED_WITH_WARNING) {
-                trace.report(Errors.UNSUPPORTED_FEATURE.on(node.psi, diagnosticData))
+                trace.report(Errors.EXPERIMENTAL_FEATURE_WARNING.on(node.psi, diagnosticData))
             }
-            else {
-                trace.report(Errors.EXPERIMENTAL_FEATURE_ERROR.on(node.psi, diagnosticData))
-            }
-            return false
-        }
-
-        if (featureSupport == LanguageFeature.State.ENABLED_WITH_WARNING) {
-            trace.report(Errors.EXPERIMENTAL_FEATURE_WARNING.on(node.psi, diagnosticData))
         }
 
         return true

compiler/testData/codegen/box/properties/lateinit/local/capturedLocalLateinit.kt

@@ -1,3 +1,5 @@
+// LANGUAGE_VERSION: 1.2
+
 fun runNoInline(f: () -> Unit) = f()
 
 fun box(): String {

compiler/testData/codegen/box/properties/lateinit/local/localLateinit.kt

@@ -1,3 +1,5 @@
+// LANGUAGE_VERSION: 1.2
+
 fun box(): String {
     lateinit var ok: String
     run {

compiler/testData/codegen/box/properties/lateinit/local/uninitializedCapturedMemberAccess.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 

compiler/testData/codegen/box/properties/lateinit/local/uninitializedCapturedRead.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 

compiler/testData/codegen/box/properties/lateinit/local/uninitializedMemberAccess.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 

compiler/testData/codegen/box/properties/lateinit/local/uninitializedRead.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 

compiler/testData/codegen/box/properties/lateinit/topLevel/accessorException.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 // FILE: lateinit.kt

compiler/testData/codegen/box/properties/lateinit/topLevel/accessorForTopLevelLateinit.kt

@@ -1,3 +1,5 @@
+// LANGUAGE_VERSION: 1.2
+
 // FILE: lateinit.kt
 private lateinit var s: String
 

compiler/testData/codegen/box/properties/lateinit/topLevel/topLevelLateinit.kt

@@ -1,3 +1,5 @@
+// LANGUAGE_VERSION: 1.2
+
 lateinit var ok: String
 
 fun box(): String {

compiler/testData/codegen/box/properties/lateinit/topLevel/uninitializedMemberAccess.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 

compiler/testData/codegen/box/properties/lateinit/topLevel/uninitializedRead.kt

@@ -1,3 +1,4 @@
+// LANGUAGE_VERSION: 1.2
 // WITH_REFLECT
 // IGNORE_BACKEND: JS, NATIVE
 

compiler/testData/diagnostics/tests/lateinit/modifierApplicability.kt

@@ -19,7 +19,7 @@ public abstract class A<T: Any, V: String?>(<!INAPPLICABLE_LATEINIT_MODIFIER!>la
         private set
 
     fun a() {
-        lateinit var <!UNUSED_VARIABLE!>a<!>: String
+        <!UNSUPPORTED_FEATURE!>lateinit<!> var <!UNUSED_VARIABLE!>a<!>: String
     }
 
     <!INAPPLICABLE_LATEINIT_MODIFIER!>lateinit<!> var e1: V
@@ -46,8 +46,8 @@ public abstract class A<T: Any, V: String?>(<!INAPPLICABLE_LATEINIT_MODIFIER!>la
     <!INAPPLICABLE_LATEINIT_MODIFIER!>lateinit<!> var String.e12: String
 }
 
-<!INAPPLICABLE_LATEINIT_MODIFIER!>lateinit<!> val topLevel: String
+<!INAPPLICABLE_LATEINIT_MODIFIER, UNSUPPORTED_FEATURE!>lateinit<!> val topLevel: String
-lateinit var topLevelMutable: String
+<!UNSUPPORTED_FEATURE!>lateinit<!> var topLevelMutable: String
 
 public interface Intf {
     <!INAPPLICABLE_LATEINIT_MODIFIER!>lateinit<!> var str: String

compiler/testData/diagnostics/tests/properties/lateinitOnTopLevel.kt

@@ -1,3 +1,5 @@
+// !LANGUAGE: +LateinitTopLevelProperties
+
 object Delegate {
     operator fun getValue(instance: Any?, property: Any) : String = ""
     operator fun setValue(instance: Any?, property: Any, value: String) {}

compiler/testData/diagnostics/tests/properties/localLateinit/inapplicableLateinitModifier.kt

@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VALUE -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+// !LANGUAGE: +LateinitLocalVariables
 
 import kotlin.reflect.KProperty
 

compiler/testData/diagnostics/tests/properties/localLateinit/localLateinit.kt

@@ -1,3 +1,5 @@
+// !LANGUAGE: +LateinitLocalVariables
+
 fun test() {
     lateinit var s: String
     s = ""

compiler/testData/diagnostics/tests/properties/localLateinit/uninitialized.kt

@@ -1,3 +1,5 @@
+// !LANGUAGE: +LateinitLocalVariables
+
 fun test1() {
     lateinit var s: String
     s.length

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -57,6 +57,8 @@ enum class LanguageFeature(
     SafeCastCheckBoundSmartCasts(KOTLIN_1_2),
     BooleanElvisBoundSmartCasts(KOTLIN_1_2),
     CapturedInClosureSmartCasts(KOTLIN_1_2),
+    LateinitTopLevelProperties(KOTLIN_1_2),
+    LateinitLocalVariables(KOTLIN_1_2),
 
     // Experimental features
 

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KeywordCompletion.kt

@@ -29,6 +29,7 @@ import com.intellij.psi.tree.IElementType
 import com.intellij.psi.tree.TokenSet
 import org.jetbrains.kotlin.KtNodeTypes
 import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.config.LanguageVersionSettingsImpl
 import org.jetbrains.kotlin.descriptors.annotations.KotlinTarget
 import org.jetbrains.kotlin.descriptors.annotations.KotlinTarget.*
@@ -328,6 +329,9 @@ object KeywordCompletion {
         fun isKeywordCorrectlyApplied(keywordTokenType: KtKeywordToken, file: KtFile): Boolean {
             val elementAt = file.findElementAt(prefixText.length)!!
 
+            val languageVersionSettings = ModuleUtilCore.findModuleForPsiElement(position)?.languageVersionSettings
+                                          ?: LanguageVersionSettingsImpl.DEFAULT
+
             when {
                 !elementAt.node!!.elementType.matchesKeyword(keywordTokenType) -> return false
 
@@ -335,7 +339,7 @@ object KeywordCompletion {
 
                 isErrorElementBefore(elementAt) -> return false
 
-                !isSupportedAtLanguageLevel(keywordTokenType, position) -> return false
+                !isModifierSupportedAtLanguageLevel(keywordTokenType, languageVersionSettings) -> return false
 
                 keywordTokenType !is KtModifierKeywordToken -> return true
 
@@ -358,10 +362,13 @@ object KeywordCompletion {
 
                         is KtFile -> listOf(CLASS_ONLY, INTERFACE, OBJECT, ENUM_CLASS, ANNOTATION_CLASS, TOP_LEVEL_FUNCTION, TOP_LEVEL_PROPERTY, FUNCTION, PROPERTY)
 
-                        else -> null
+                        else -> listOf()
                     }
-                    val modifierTargets = ModifierCheckerCore.possibleTargetMap[keywordTokenType]
+                    val modifierTargets = ModifierCheckerCore.possibleTargetMap[keywordTokenType]?.intersect(possibleTargets)
-                    if (modifierTargets != null && possibleTargets != null && possibleTargets.none { it in modifierTargets }) return false
+                    if (modifierTargets != null && possibleTargets.isNotEmpty() &&
+                        !modifierTargets.any {
+                            isModifierTargetSupportedAtLanguageLevel(keywordTokenType, it, languageVersionSettings)
+                        }) return false
 
                     val ownerDeclaration = container?.getParentOfType<KtDeclaration>(strict = true)
                     val parentTarget = when (ownerDeclaration) {
@@ -416,9 +423,7 @@ object KeywordCompletion {
         }
     }
 
-    private fun isSupportedAtLanguageLevel(keyword: KtKeywordToken, position: PsiElement): Boolean {
+    private fun isModifierSupportedAtLanguageLevel(keyword: KtKeywordToken, languageVersionSettings: LanguageVersionSettings): Boolean {
-        val languageVersionSettings = ModuleUtilCore.findModuleForPsiElement(position)?.languageVersionSettings
-                                      ?: LanguageVersionSettingsImpl.DEFAULT
         val feature = when (keyword) {
             KtTokens.TYPE_ALIAS_KEYWORD -> LanguageFeature.TypeAliases
             KtTokens.HEADER_KEYWORD, KtTokens.IMPL_KEYWORD -> LanguageFeature.MultiPlatformProjects
@@ -428,6 +433,24 @@ object KeywordCompletion {
         return languageVersionSettings.supportsFeature(feature)
     }
 
+    private fun isModifierTargetSupportedAtLanguageLevel(
+            keyword: KtKeywordToken,
+            target: KotlinTarget,
+            languageVersionSettings: LanguageVersionSettings
+    ): Boolean {
+        if (keyword == KtTokens.LATEINIT_KEYWORD) {
+            val feature = when (target) {
+                TOP_LEVEL_PROPERTY -> LanguageFeature.LateinitTopLevelProperties
+                LOCAL_VARIABLE -> LanguageFeature.LateinitLocalVariables
+                else -> return true
+            }
+            return languageVersionSettings.supportsFeature(feature)
+        }
+        else {
+            return true
+        }
+    }
+
     // builds text within scope (or from the start of the file) before position element excluding almost all declarations
     private fun buildReducedContextBefore(builder: StringBuilder, position: PsiElement, scope: PsiElement?) {
         if (position == scope) return