Unused import: support also imports as alias

#KT-12392 Fixed

idea/ide-common/src/org/jetbrains/kotlin/idea/util/OptimizedImportsBuilder.kt

@@ -61,7 +61,7 @@ class OptimizedImportsBuilder(
     }
 
     data class InputData(
-        val descriptorsToImport: Set<DeclarationDescriptor>,
+        val descriptorsToImport: Map<DeclarationDescriptor, Set<Name>>,
         val references: Collection<AbstractReference>
     )
 
@@ -124,7 +124,7 @@ class OptimizedImportsBuilder(
             .mapTo(importsToGenerate) { it.importPath }
 
         val descriptorsByParentFqName = HashMap<FqName, MutableSet<DeclarationDescriptor>>()
-        for (descriptor in data.descriptorsToImport) {
+        for (descriptor in data.descriptorsToImport.keys) {
             val fqName = descriptor.importableFqName!!
 
             val explicitImportPath = ImportPath(fqName, false)

idea/src/org/jetbrains/kotlin/idea/imports/KotlinImportOptimizer.kt

@@ -79,7 +79,7 @@ class KotlinImportOptimizer : ImportOptimizer {
             .mapNotNull(KtImportDirective::importedFqName)
             .toSet()
 
-        private val descriptorsToImport = HashSet<DeclarationDescriptor>()
+        private val descriptorsToImport = LinkedHashMap<DeclarationDescriptor, Set<Name>>()
         private val abstractRefs = ArrayList<OptimizedImportsBuilder.AbstractReference>()
 
         val data: OptimizedImportsBuilder.InputData
@@ -107,7 +107,6 @@ class KotlinImportOptimizer : ImportOptimizer {
                 val targets = reference.targets(bindingContext)
                 for (target in targets) {
                     val importableDescriptor = target.getImportableDescriptor()
-                    if (importableDescriptor.name !in names) continue // resolved via alias
 
                     val importableFqName = target.importableFqName ?: continue
                     val parentFqName = importableFqName.parent()
@@ -118,7 +117,7 @@ class KotlinImportOptimizer : ImportOptimizer {
 
                     if (isAccessibleAsMember(importableDescriptor, element, bindingContext)) continue
 
-                    descriptorsToImport.add(importableDescriptor)
+                    descriptorsToImport.compute(importableDescriptor) { _, u -> u?.plus(names) ?: names.toHashSet() }
                 }
             }
 

idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt

@@ -49,12 +49,12 @@ import org.jetbrains.kotlin.idea.imports.OptimizedImportsBuilder
 import org.jetbrains.kotlin.idea.imports.importableFqName
 import org.jetbrains.kotlin.idea.util.ProjectRootsUtil
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.KtCodeFragment
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi.KtImportDirective
 import org.jetbrains.kotlin.psi.psiUtil.siblings
 import org.jetbrains.kotlin.resolve.ImportPath
-import java.util.*
 
 class KotlinUnusedImportInspection : AbstractKotlinInspection() {
     data class ImportData(val unusedImports: List<KtImportDirective>, val optimizerData: OptimizedImportsBuilder.InputData)
@@ -75,11 +75,11 @@ class KotlinUnusedImportInspection : AbstractKotlinInspection() {
                 .map { it.fqName }
                 .toSet()
 
-            val fqNames = HashSet<FqName>()
+            val fqNames = HashMap<FqName, Set<Name>>()
             val parentFqNames = HashSet<FqName>()
-            for (descriptor in optimizerData.descriptorsToImport) {
+            for ((descriptor, names) in optimizerData.descriptorsToImport) {
                 val fqName = descriptor.importableFqName!!
-                fqNames.add(fqName)
+                fqNames.compute(fqName) { _, u -> u?.plus(names) ?: names }
 
                 if (fqName !in explicitlyImportedFqNames) { // we don't add parents of explicitly imported fq-names because such imports are not needed
                     val parentFqName = fqName.parent()
@@ -95,12 +95,11 @@ class KotlinUnusedImportInspection : AbstractKotlinInspection() {
             val resolutionFacade = file.getResolutionFacade()
             for (directive in directives) {
                 val importPath = directive.importPath ?: continue
-                if (importPath.alias != null) continue // highlighting of unused alias imports not supported yet
 
                 val isUsed = when {
                     !importPaths.add(importPath) -> false
                     importPath.isAllUnder -> importPath.fqName in parentFqNames
-                    importPath.fqName in fqNames -> true
+                    importPath.fqName in fqNames -> importPath.importedName?.let { it in fqNames.getValue(importPath.fqName) } ?: false
                     // case for type alias
                     else -> directive.targetDescriptors(resolutionFacade).firstOrNull()?.let { it.importableFqName in fqNames } ?: false
                 }

idea/testData/inspections/unusedImport/file.kt

@@ -7,11 +7,12 @@ import java.util.ArrayList // used
 import java.unresolved.* // unused but unresolved
 import java.net.Unresolved // unused but unresolved
 
-import java.net.ConnectException as CE // highlighting of unused aliases not implemented yet
+import java.net.ConnectException as CE // unused
+import java.net.ConnectException as ConExc // used
 
 import RootPackageClass // unused because it's in the current package
 
-fun foo(list: ArrayList<String>, p: RootPackageClass) {
+fun foo(list: ArrayList<String>, p: RootPackageClass, e: ConExc) {
     list.add("")
     Date()
 }

idea/testData/inspections/unusedImport/inspectionData/expected.xml

@@ -17,6 +17,15 @@
         <description>Unused import directive</description>
     </problem>
 
+    <problem>
+        <file>file.kt</file>
+        <line>10</line>
+        <module>light_idea_test_case</module>
+        <entry_point TYPE="file" FQNAME="simple.kt" />
+        <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused import directive</problem_class>
+        <description>Unused import directive</description>
+    </problem>
+
     <problem>
         <file>fileInPack1.kt</file>
         <line>3</line>