Do not report 'const' inapplicability on property of error type

 #KT-12477 Fixed

Author: zarechenskiy

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ConstModifierChecker.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,46 +37,59 @@ object ConstModifierChecker : SimpleDeclarationChecker {
 
         val constModifierPsiElement = declaration.modifierList!!.getModifier(KtTokens.CONST_KEYWORD)!!
 
-        val diagnostic = checkCanBeConst(declaration, constModifierPsiElement, descriptor)
+        val diagnostic = checkCanBeConst(declaration, constModifierPsiElement, descriptor).diagnostic
         if (diagnostic != null) {
             diagnosticHolder.report(diagnostic)
         }
     }
 
-    fun checkCanBeConst(declaration: KtDeclaration,
+    fun canBeConst(declaration: KtDeclaration, constModifierPsiElement: PsiElement, descriptor: VariableDescriptor): Boolean =
+            checkCanBeConst(declaration, constModifierPsiElement, descriptor).canBeConst
+
+    private fun checkCanBeConst(declaration: KtDeclaration,
                         constModifierPsiElement: PsiElement,
-                        descriptor: VariableDescriptor): Diagnostic? {
+                        descriptor: VariableDescriptor): ConstApplicability {
         if (descriptor.isVar) {
-            return Errors.WRONG_MODIFIER_TARGET.on(constModifierPsiElement, KtTokens.CONST_KEYWORD, "vars")
+            return Errors.WRONG_MODIFIER_TARGET.on(constModifierPsiElement, KtTokens.CONST_KEYWORD, "vars").nonApplicable()
         }
 
         val containingDeclaration = descriptor.containingDeclaration
         if (containingDeclaration is ClassDescriptor && containingDeclaration.kind != ClassKind.OBJECT) {
-            return Errors.CONST_VAL_NOT_TOP_LEVEL_OR_OBJECT.on(constModifierPsiElement)
+            return Errors.CONST_VAL_NOT_TOP_LEVEL_OR_OBJECT.on(constModifierPsiElement).nonApplicable()
         }
 
-        if (declaration !is KtProperty || descriptor !is PropertyDescriptor) return null
+        if (declaration !is KtProperty || descriptor !is PropertyDescriptor) return ConstApplicability.NonApplicable()
 
         if (declaration.hasDelegate()) {
-            return Errors.CONST_VAL_WITH_DELEGATE.on(declaration.delegate!!)
+            return Errors.CONST_VAL_WITH_DELEGATE.on(declaration.delegate!!).nonApplicable()
         }
 
         if (descriptor is PropertyDescriptor && !descriptor.getter!!.isDefault) {
-            return Errors.CONST_VAL_WITH_GETTER.on(declaration.getter!!)
+            return Errors.CONST_VAL_WITH_GETTER.on(declaration.getter!!).nonApplicable()
         }
 
+        if (descriptor.type.isError) return ConstApplicability.NonApplicable()
+
+        // Report errors about const initializer only on property of resolved types
         if (!descriptor.type.canBeUsedForConstVal()) {
-            return Errors.TYPE_CANT_BE_USED_FOR_CONST_VAL.on(constModifierPsiElement, descriptor.type)
+            return Errors.TYPE_CANT_BE_USED_FOR_CONST_VAL.on(constModifierPsiElement, descriptor.type).nonApplicable()
         }
 
         if (declaration.initializer == null) {
-            return Errors.CONST_VAL_WITHOUT_INITIALIZER.on(constModifierPsiElement)
+            return Errors.CONST_VAL_WITHOUT_INITIALIZER.on(constModifierPsiElement).nonApplicable()
         }
 
         if (descriptor.compileTimeInitializer == null) {
-            return Errors.CONST_VAL_WITH_NON_CONST_INITIALIZER.on(declaration.initializer!!)
+            return Errors.CONST_VAL_WITH_NON_CONST_INITIALIZER.on(declaration.initializer!!).nonApplicable()
         }
 
-        return null
+        return ConstApplicability.Applicable
     }
 }
+
+sealed class ConstApplicability(val canBeConst: Boolean, val diagnostic: Diagnostic?) {
+    object Applicable : ConstApplicability(true, null)
+    class NonApplicable(diagnostic: Diagnostic? = null) : ConstApplicability(false, diagnostic)
+}
+
+private fun Diagnostic.nonApplicable() = ConstApplicability.NonApplicable(this)

compiler/testData/diagnostics/tests/modifiers/const/types.kt

@@ -10,3 +10,8 @@ enum class MyEnum { A }
 <!TYPE_CANT_BE_USED_FOR_CONST_VAL!>const<!> val enumConst: MyEnum = MyEnum.A
 <!TYPE_CANT_BE_USED_FOR_CONST_VAL!>const<!> val arrayConst: Array<String> = arrayOf("1")
 <!TYPE_CANT_BE_USED_FOR_CONST_VAL!>const<!> val intArrayConst: IntArray = intArrayOf()
+
+const val unresolvedConst1 = <!UNRESOLVED_REFERENCE!>Unresolved<!>
+<!WRONG_MODIFIER_TARGET!>const<!> var unresolvedConst2 = <!UNRESOLVED_REFERENCE!>Unresolved<!>
+const val unresolvedConst3 = <!UNRESOLVED_REFERENCE, PROPERTY_INITIALIZER_NO_BACKING_FIELD!>Unresolved<!>
+<!CONST_VAL_WITH_GETTER!>get() = 10<!>

compiler/testData/diagnostics/tests/modifiers/const/types.txt

@@ -7,6 +7,9 @@ public const val intArrayConst: kotlin.IntArray
 public const val intConst: kotlin.Int = 1
 public const val longConst: kotlin.Long = 1.toLong()
 public const val stringConst: kotlin.String = "empty"
+public const val unresolvedConst1: [ERROR : Type for Unresolved]
+public const var unresolvedConst2: [ERROR : Type for Unresolved]
+public const val unresolvedConst3: [ERROR : Type for Unresolved]
 
 public final enum class MyEnum : kotlin.Enum<MyEnum> {
     enum entry A

idea/src/org/jetbrains/kotlin/idea/quickfix/AddConstModifierFix.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -77,7 +77,7 @@ class AddConstModifierIntention : SelfTargetingIntention<KtProperty>(KtProperty:
                 return false
             }
             val propertyDescriptor = element.descriptor as? VariableDescriptor ?: return false
-            return ConstModifierChecker.checkCanBeConst(element, element, propertyDescriptor) == null
+            return ConstModifierChecker.canBeConst(element, element, propertyDescriptor)
         }
     }
 }
@@ -89,7 +89,7 @@ object ConstFixFactory : KotlinSingleIntentionActionFactory() {
         val bindingContext = expr.analyze(BodyResolveMode.PARTIAL)
         val targetDescriptor = bindingContext.get(BindingContext.REFERENCE_TARGET, expr) as? VariableDescriptor ?: return null
         val declaration = (targetDescriptor.source as? PsiSourceElement)?.psi as? KtProperty ?: return null
-        if (ConstModifierChecker.checkCanBeConst(declaration, declaration, targetDescriptor) == null) {
+        if (ConstModifierChecker.canBeConst(declaration, declaration, targetDescriptor)) {
             return AddConstModifierFix(declaration)
         }
         return null