Hopefully fixed KT-4339 Auto-import suggestion doesn't go away for a long time

#KT-4339 Fixed

compiler/util/src/org/jetbrains/jet/utils/CachedValueProperty.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2014 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.utils
+
+import kotlin.properties.ReadOnlyProperty
+
+public class CachedValueProperty<TValue : Any, TTimestamp : Any>(private val calculator: () -> TValue,
+                                                         private val timestampCalculator: () -> TTimestamp) : ReadOnlyProperty<Any?, TValue> {
+    private var value: TValue? = null
+    private var timestamp: TTimestamp? = null
+
+    public override fun get(thisRef: Any?, desc: PropertyMetadata): TValue {
+        val currentTimestamp = timestampCalculator()
+        if (value == null || timestamp != currentTimestamp) {
+            value = calculator()
+            timestamp = currentTimestamp
+        }
+        return value!!
+    }
+}

idea/src/org/jetbrains/jet/plugin/quickfix/AutoImportFix.kt

@@ -53,6 +53,9 @@ import org.jetbrains.jet.plugin.search.searchScopeForSourceElementDependencies
 import org.jetbrains.jet.lang.resolve.BindingContext
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptorWithVisibility
 import org.jetbrains.jet.lang.descriptors.Visibilities
+import org.jetbrains.jet.lang.diagnostics.Errors
+import com.intellij.psi.util.PsiModificationTracker
+import org.jetbrains.jet.utils.CachedValueProperty
 
 /**
  * Check possibility and perform fix for unresolved references.
@@ -60,7 +63,9 @@ import org.jetbrains.jet.lang.descriptors.Visibilities
 public class AutoImportFix(element: JetSimpleNameExpression) : JetHintAction<JetSimpleNameExpression>(element), HighPriorityAction {
     private val module = ModuleUtilCore.findModuleForPsiElement(element)
 
-    private val suggestions: Collection<FqName> = computeSuggestions(element)
+    private val suggestions: Collection<FqName>
+            by CachedValueProperty({ computeSuggestions(element) },
+                           { PsiModificationTracker.SERVICE.getInstance(element.getProject()).getModificationCount() })
 
     override fun showHint(editor: Editor): Boolean {
         if (suggestions.isEmpty()) return false
@@ -84,7 +89,7 @@ public class AutoImportFix(element: JetSimpleNameExpression) : JetHintAction<Jet
             = JetBundle.message("import.fix")
 
     override fun isAvailable(project: Project, editor: Editor, file: PsiFile)
-            = super< JetHintAction>.isAvailable(project, editor, file) && !suggestions.isEmpty()
+            = super<JetHintAction>.isAvailable(project, editor, file) && !suggestions.isEmpty()
 
     override fun invoke(project: Project, editor: Editor?, file: JetFile?) {
         CommandProcessor.getInstance().runUndoTransparentAction {
@@ -99,6 +104,8 @@ public class AutoImportFix(element: JetSimpleNameExpression) : JetHintAction<Jet
             = JetAddImportAction(project, editor, element, suggestions)
 
     private fun computeSuggestions(element: JetSimpleNameExpression): Collection<FqName> {
+        if (!element.isValid()) return listOf()
+
         val file = element.getContainingFile() as? JetFile ?: return listOf()
 
         var referenceName = element.getReferencedName()
@@ -114,7 +121,12 @@ public class AutoImportFix(element: JetSimpleNameExpression) : JetHintAction<Jet
 
         val searchScope = searchScopeForSourceElementDependencies(file) ?: return listOf()
 
-        val resolutionScope = resolveSession.resolveToElement(element)[BindingContext.RESOLUTION_SCOPE, element] ?: return listOf()
+        val bindingContext = resolveSession.resolveToElement(element)
+
+        val diagnostics = bindingContext.getDiagnostics().forElement(element)
+        if (!diagnostics.any { it.getFactory() in ERRORS }) return listOf()
+
+        val resolutionScope = bindingContext[BindingContext.RESOLUTION_SCOPE, element] ?: return listOf()
         val containingDescriptor = resolutionScope.getContainingDeclaration()
 
         fun isVisible(descriptor: DeclarationDescriptor): Boolean {
@@ -192,6 +204,8 @@ public class AutoImportFix(element: JetSimpleNameExpression) : JetHintAction<Jet
     }
 
     class object {
+        private val ERRORS = setOf(Errors.UNRESOLVED_REFERENCE, Errors.UNRESOLVED_REFERENCE_WRONG_RECEIVER)
+
         public fun createFactory(): JetSingleIntentionActionFactory {
             return object : JetSingleIntentionActionFactory() {
                 override fun createAction(diagnostic: Diagnostic): JetIntentionAction<JetSimpleNameExpression>? {