Don't delete import from stdlib if alias exists and used

#KT-31414 Fixed

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

@@ -60,7 +60,8 @@ class OptimizedImportsBuilder(
     }
 
     data class InputData(
-        val descriptorsToImport: Map<DeclarationDescriptor, Set<Name>>,
+        val descriptorsToImport: Set<DeclarationDescriptor>,
+        val namesToImport: Map<FqName, Set<Name>>,
         val references: Collection<AbstractReference>
     )
 
@@ -119,9 +120,9 @@ class OptimizedImportsBuilder(
             .mapTo(importsToGenerate) { it.importPath }
 
         val descriptorsByParentFqName = HashMap<FqName, MutableSet<DeclarationDescriptor>>()
-        for ((descriptor, names) in data.descriptorsToImport) {
+        for (descriptor in data.descriptorsToImport) {
-            for (name in names) {
+            val fqName = descriptor.importableFqName!!
-                val fqName = descriptor.importableFqName!!
+            for (name in data.namesToImport.getValue(fqName)) {
                 val alias = if (name != fqName.shortName()) name else null
 
                 val explicitImportPath = ImportPath(fqName, false, alias)
@@ -149,16 +150,16 @@ class OptimizedImportsBuilder(
                     || !starImportPath.isAllowedByRules()
             if (useExplicitImports) {
                 fqNames
-                    .filter { !isImportedByDefault(it) }
+                    .filter(this::needExplicitImport)
                     .mapTo(importsToGenerate) { ImportPath(it, false) }
             } else {
                 descriptors
                     .asSequence()
                     .filterIsInstance<ClassDescriptor>()
                     .map { it.importableFqName!! }
-                    .filterTo(classNamesToCheck) { !isImportedByDefault(it) }
+                    .filterTo(classNamesToCheck, this::needExplicitImport)
 
-                if (!fqNames.all(this::isImportedByDefault)) {
+                if (fqNames.all(this::needExplicitImport)) {
                     importsToGenerate.add(starImportPath)
                 }
             }
@@ -205,7 +206,7 @@ class OptimizedImportsBuilder(
                         (oldTargets + newTargets).forEach {
                             lockImportForDescriptor(
                                 it,
-                                data.descriptorsToImport.getOrElse(it) { listOf(it.name) }.intersect(names)
+                                data.namesToImport.getOrElse(it.importableFqName!!) { listOf(it.name) }.intersect(names)
                             )
                         }
                     }
@@ -321,6 +322,12 @@ class OptimizedImportsBuilder(
         }
     }
 
+    private fun needExplicitImport(fqName: FqName): Boolean = hasAlias(fqName) || !isImportedByDefault(fqName)
+
+    private fun hasAlias(fqName: FqName) = data.namesToImport[fqName]?.let {
+        it.singleOrNull() == null
+    } ?: false
+
     private fun isImportedByDefault(fqName: FqName) = importInsertHelper.isImportedWithDefault(ImportPath(fqName, false), file)
 
     private fun isImportedByLowPriorityDefault(fqName: FqName) =

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

@@ -79,11 +79,12 @@ class KotlinImportOptimizer : ImportOptimizer {
             .mapNotNull { it.importPath }
             .groupBy(keySelector = { it.fqName }, valueTransform = { it.importedName as Name })
 
-        private val descriptorsToImport = LinkedHashMap<DeclarationDescriptor, HashSet<Name>>()
+        private val descriptorsToImport = LinkedHashSet<DeclarationDescriptor>()
+        private val namesToImport = LinkedHashMap<FqName, HashSet<Name>>()
         private val abstractRefs = ArrayList<OptimizedImportsBuilder.AbstractReference>()
 
         val data: OptimizedImportsBuilder.InputData
-            get() = OptimizedImportsBuilder.InputData(descriptorsToImport, abstractRefs)
+            get() = OptimizedImportsBuilder.InputData(descriptorsToImport, namesToImport, abstractRefs)
 
         override fun visitElement(element: PsiElement) {
             ProgressIndicatorProvider.checkCanceled()
@@ -119,7 +120,8 @@ class KotlinImportOptimizer : ImportOptimizer {
                     if (isAccessibleAsMember(importableDescriptor, element, bindingContext)) continue
 
                     val descriptorNames = (aliases[importableFqName].orEmpty() + importableFqName.shortName()).intersect(names)
-                    descriptorsToImport.getOrPut(importableDescriptor) { LinkedHashSet() } += descriptorNames
+                    namesToImport.getOrPut(importableFqName) { LinkedHashSet() } += descriptorNames
+                    descriptorsToImport += importableDescriptor
                 }
             }
 

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

@@ -49,7 +49,6 @@ 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
@@ -75,12 +74,10 @@ class KotlinUnusedImportInspection : AbstractKotlinInspection() {
                 .map { it.fqName }
                 .toSet()
 
-            val fqNames = HashMap<FqName, Set<Name>>()
+            val fqNames = optimizerData.namesToImport
             val parentFqNames = HashSet<FqName>()
-            for ((descriptor, names) in optimizerData.descriptorsToImport) {
+            for (descriptor in optimizerData.descriptorsToImport) {
                 val fqName = descriptor.importableFqName!!
-                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()
                     if (!parentFqName.isRoot) {

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias.dependency.kt

@@ -0,0 +1,9 @@
+package pack1
+
+fun a() {
+
+}
+
+fun Int.a() {
+
+}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias.kt

@@ -0,0 +1,15 @@
+import pack1.a
+import pack1.a as a1
+import kotlin.collections.List
+import kotlin.collections.List as List1
+import kotlin.run as run1
+import kotlin.run
+
+fun foo() {
+    run {}
+    run1 {}
+    List<String>(1) {}
+    List1<String>(1) {}
+    a()
+    a1()
+}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias.kt.after

@@ -0,0 +1,15 @@
+import pack1.a
+import kotlin.collections.List
+import kotlin.run
+import pack1.a as a1
+import kotlin.collections.List as List1
+import kotlin.run as run1
+
+fun foo() {
+    run {}
+    run1 {}
+    List<String>(1) {}
+    List1<String>(1) {}
+    a()
+    a1()
+}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias.kt.log

@@ -0,0 +1,37 @@
+Additional checking of reference Getter: List
+Additional checking of reference KtSimpleNameReference: List
+Additional checking of reference Getter: List1
+Additional checking of reference KtSimpleNameReference: List1
+Changed resolve of KtSimpleNameReference: List1
+Additional checking of reference Getter: a1
+Additional checking of reference KtSimpleNameReference: a1
+Changed resolve of KtSimpleNameReference: a1
+Additional checking of reference Getter: run
+Additional checking of reference KtSimpleNameReference: run
+Additional checking of reference Getter: run1
+Additional checking of reference KtSimpleNameReference: run1
+Changed resolve of KtSimpleNameReference: run1
+Additional checking of reference KtInvokeFunctionReference: List1<String>(1) {}
+Additional checking of reference KtInvokeFunctionReference: List<String>(1) {}
+Additional checking of reference KtInvokeFunctionReference: a1()
+Additional checking of reference KtInvokeFunctionReference: run {}
+Additional checking of reference KtInvokeFunctionReference: run1 {}
+Trying to build import list again with import rules: +pack1.a as a1, +kotlin.collections.List as List1, +kotlin.run as run1
+Additional checking of reference Getter: List
+Additional checking of reference KtSimpleNameReference: List
+Additional checking of reference Getter: List1
+Additional checking of reference KtSimpleNameReference: List1
+Changed resolve of KtSimpleNameReference: List1
+Additional checking of reference Getter: a1
+Additional checking of reference KtSimpleNameReference: a1
+Changed resolve of KtSimpleNameReference: a1
+Additional checking of reference Getter: run
+Additional checking of reference KtSimpleNameReference: run
+Additional checking of reference Getter: run1
+Additional checking of reference KtSimpleNameReference: run1
+Changed resolve of KtSimpleNameReference: run1
+Additional checking of reference KtInvokeFunctionReference: List1<String>(1) {}
+Additional checking of reference KtInvokeFunctionReference: List<String>(1) {}
+Additional checking of reference KtInvokeFunctionReference: a1()
+Additional checking of reference KtInvokeFunctionReference: run {}
+Additional checking of reference KtInvokeFunctionReference: run1 {}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias2.dependency.kt

@@ -0,0 +1,9 @@
+package pack1
+
+fun a() {
+
+}
+
+fun Int.a() {
+
+}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias2.kt

@@ -0,0 +1,10 @@
+import pack1.a
+import pack1.a as a1
+import kotlin.run as run1
+import kotlin.run
+
+fun foo() {
+    run1 {}
+    a()
+    42.a1()
+}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias2.kt.after

@@ -0,0 +1,9 @@
+import pack1.a
+import pack1.a as a1
+import kotlin.run as run1
+
+fun foo() {
+    run1 {}
+    a()
+    42.a1()
+}

idea/testData/editor/optimizeImports/common/DefaultImportAndAlias2.kt.log

@@ -0,0 +1,17 @@
+Additional checking of reference Getter: a1
+Additional checking of reference KtSimpleNameReference: a1
+Changed resolve of KtSimpleNameReference: a1
+Additional checking of reference Getter: run1
+Additional checking of reference KtSimpleNameReference: run1
+Changed resolve of KtSimpleNameReference: run1
+Additional checking of reference KtInvokeFunctionReference: a1()
+Additional checking of reference KtInvokeFunctionReference: run1 {}
+Trying to build import list again with import rules: +pack1.a as a1, +kotlin.run as run1
+Additional checking of reference Getter: a1
+Additional checking of reference KtSimpleNameReference: a1
+Changed resolve of KtSimpleNameReference: a1
+Additional checking of reference Getter: run1
+Additional checking of reference KtSimpleNameReference: run1
+Changed resolve of KtSimpleNameReference: run1
+Additional checking of reference KtInvokeFunctionReference: a1()
+Additional checking of reference KtInvokeFunctionReference: run1 {}

idea/testData/editor/optimizeImports/common/TwoConstructors.kt.after

@@ -1,5 +1,5 @@
 // NAME_COUNT_TO_USE_STAR_IMPORT: 2
-import p1.A
+import p1.*
 import p2.A
 
 fun f() {

idea/testData/editor/optimizeImports/common/TwoConstructors.kt.log

@@ -6,3 +6,4 @@ Additional checking of reference KtSimpleNameReference: A
 Changed resolve of KtSimpleNameReference: A
 Additional checking of reference KtInvokeFunctionReference: A("")
 Additional checking of reference KtInvokeFunctionReference: A(1)
+Trying to build import list again with import rules: +p2.A, +p1.*

idea/testData/editor/optimizeImports/common/WithAlias.dependency.kt

@@ -0,0 +1,9 @@
+package pack1
+
+fun a() {
+
+}
+
+fun Int.a() {
+
+}

idea/testData/editor/optimizeImports/common/WithAlias.kt

@@ -0,0 +1,6 @@
+import pack1.a
+import pack1.a as a1
+
+fun foo() {
+    42.a1()
+}

idea/testData/editor/optimizeImports/common/WithAlias.kt.after

@@ -0,0 +1,5 @@
+import pack1.a as a1
+
+fun foo() {
+    42.a1()
+}

idea/testData/editor/optimizeImports/common/WithAlias.kt.log

@@ -0,0 +1,9 @@
+Additional checking of reference Getter: a1
+Additional checking of reference KtSimpleNameReference: a1
+Changed resolve of KtSimpleNameReference: a1
+Additional checking of reference KtInvokeFunctionReference: a1()
+Trying to build import list again with import rules: +pack1.a as a1
+Additional checking of reference Getter: a1
+Additional checking of reference KtSimpleNameReference: a1
+Changed resolve of KtSimpleNameReference: a1
+Additional checking of reference KtInvokeFunctionReference: a1()

idea/testData/editor/optimizeImports/common/WithAlias2.dependency.kt

@@ -0,0 +1,9 @@
+package pack1
+
+fun a() {
+
+}
+
+fun Int.a() {
+
+}

idea/testData/editor/optimizeImports/common/WithAlias2.kt

@@ -0,0 +1,6 @@
+import pack1.a
+import pack1.a as a1
+
+fun foo() {
+    a()
+}

idea/testData/editor/optimizeImports/common/WithAlias2.kt.after

@@ -0,0 +1,5 @@
+import pack1.a
+
+fun foo() {
+    a()
+}

idea/testData/editor/optimizeImports/jvm/AlreadyOptimized.kt.log

@@ -2,3 +2,8 @@ Additional checking of reference Getter: JavaFile
 Additional checking of reference KtSimpleNameReference: JavaFile
 Changed resolve of KtSimpleNameReference: JavaFile
 Additional checking of reference KtInvokeFunctionReference: JavaFile(StringBuilder().append("Hello").toString())
+Trying to build import list again with import rules: +java.io.File as JavaFile
+Additional checking of reference Getter: JavaFile
+Additional checking of reference KtSimpleNameReference: JavaFile
+Changed resolve of KtSimpleNameReference: JavaFile
+Additional checking of reference KtInvokeFunctionReference: JavaFile(StringBuilder().append("Hello").toString())

idea/tests/org/jetbrains/kotlin/idea/imports/JsOptimizeImportsTestGenerated.java

@@ -79,6 +79,16 @@ public class JsOptimizeImportsTestGenerated extends AbstractJsOptimizeImportsTes
             runTest("idea/testData/editor/optimizeImports/common/CurrentPackage.kt");
         }
 
+        @TestMetadata("DefaultImportAndAlias.kt")
+        public void testDefaultImportAndAlias() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/DefaultImportAndAlias.kt");
+        }
+
+        @TestMetadata("DefaultImportAndAlias2.kt")
+        public void testDefaultImportAndAlias2() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/DefaultImportAndAlias2.kt");
+        }
+
         @TestMetadata("DefaultObjectReference.kt")
         public void testDefaultObjectReference() throws Exception {
             runTest("idea/testData/editor/optimizeImports/common/DefaultObjectReference.kt");
@@ -179,6 +189,16 @@ public class JsOptimizeImportsTestGenerated extends AbstractJsOptimizeImportsTes
             runTest("idea/testData/editor/optimizeImports/common/UnresolvedImport.kt");
         }
 
+        @TestMetadata("WithAlias.kt")
+        public void testWithAlias() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/WithAlias.kt");
+        }
+
+        @TestMetadata("WithAlias2.kt")
+        public void testWithAlias2() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/WithAlias2.kt");
+        }
+
         @TestMetadata("idea/testData/editor/optimizeImports/common/kt21515")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)

idea/tests/org/jetbrains/kotlin/idea/imports/JvmOptimizeImportsTestGenerated.java

@@ -272,6 +272,16 @@ public class JvmOptimizeImportsTestGenerated extends AbstractJvmOptimizeImportsT
             runTest("idea/testData/editor/optimizeImports/common/CurrentPackage.kt");
         }
 
+        @TestMetadata("DefaultImportAndAlias.kt")
+        public void testDefaultImportAndAlias() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/DefaultImportAndAlias.kt");
+        }
+
+        @TestMetadata("DefaultImportAndAlias2.kt")
+        public void testDefaultImportAndAlias2() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/DefaultImportAndAlias2.kt");
+        }
+
         @TestMetadata("DefaultObjectReference.kt")
         public void testDefaultObjectReference() throws Exception {
             runTest("idea/testData/editor/optimizeImports/common/DefaultObjectReference.kt");
@@ -372,6 +382,16 @@ public class JvmOptimizeImportsTestGenerated extends AbstractJvmOptimizeImportsT
             runTest("idea/testData/editor/optimizeImports/common/UnresolvedImport.kt");
         }
 
+        @TestMetadata("WithAlias.kt")
+        public void testWithAlias() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/WithAlias.kt");
+        }
+
+        @TestMetadata("WithAlias2.kt")
+        public void testWithAlias2() throws Exception {
+            runTest("idea/testData/editor/optimizeImports/common/WithAlias2.kt");
+        }
+
         @TestMetadata("idea/testData/editor/optimizeImports/common/kt21515")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)