Non-imported extensions are excluded when shadowed by members or something

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

@@ -19,7 +19,6 @@ package org.jetbrains.kotlin.idea.util
 import com.intellij.openapi.project.Project
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.di.InjectorForMacros
-import org.jetbrains.kotlin.idea.imports.canBeReferencedViaImport
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.DelegatingBindingTrace
@@ -35,13 +34,12 @@ import org.jetbrains.kotlin.resolve.scopes.ChainedScope
 import org.jetbrains.kotlin.resolve.scopes.ExplicitImportsScope
 import org.jetbrains.kotlin.resolve.validation.SymbolUsageValidator
 import org.jetbrains.kotlin.types.TypeUtils
-import java.util.ArrayList
+import java.util.*
 
 public class ShadowedDeclarationsFilter(
         private val bindingContext: BindingContext,
         private val moduleDescriptor: ModuleDescriptor,
-        private val project: Project,
-        private val importDeclarations: Boolean = false
+        private val project: Project
 ) {
     private val psiFactory = JetPsiFactory(project)
     private val dummyExpressionFactory = DummyExpressionFactory(psiFactory)
@@ -51,7 +49,27 @@ public class ShadowedDeclarationsFilter(
 
         return declarations
                 .groupBy { signature(it) }
-                .flatMap { filterEqualSignatureGroup(it.value, call) }
+                .values()
+                .flatMap { group -> filterEqualSignatureGroup(group, call) }
+    }
+
+    public fun <TDescriptor : DeclarationDescriptor> filterNonImported(
+            declarations: Collection<TDescriptor>,
+            importedDeclarations: Collection<DeclarationDescriptor>,
+            expression: JetSimpleNameExpression
+    ): Collection<TDescriptor> {
+        val importedDeclarationsSet = importedDeclarations.toSet()
+        val nonImportedDeclarations = declarations.filter { it !in importedDeclarationsSet }
+
+        val call = expression.getCall(bindingContext) ?: return nonImportedDeclarations
+
+        val notShadowed = nonImportedDeclarations
+                .groupBy { signature(it) }
+                .values()
+                .flatMapTo(HashSet<DeclarationDescriptor>()) { group ->
+                    filterEqualSignatureGroup(group + importedDeclarations, call, descriptorsToImport = group)
+                }
+        return declarations.filter { it in notShadowed }
     }
 
     private fun signature(descriptor: DeclarationDescriptor): Any {
@@ -62,7 +80,11 @@ public class ShadowedDeclarationsFilter(
         }
     }
 
-    private fun <TDescriptor : DeclarationDescriptor> filterEqualSignatureGroup(descriptors: Collection<TDescriptor>, call: Call): Collection<TDescriptor> {
+    private fun <TDescriptor : DeclarationDescriptor> filterEqualSignatureGroup(
+            descriptors: Collection<TDescriptor>,
+            call: Call,
+            descriptorsToImport: Collection<TDescriptor> = emptyList()
+    ): Collection<TDescriptor> {
         if (descriptors.size() == 1) return descriptors
 
         val first = descriptors.first()
@@ -128,10 +150,9 @@ public class ShadowedDeclarationsFilter(
         val calleeExpression = call.getCalleeExpression() ?: return descriptors
         var resolutionScope = bindingContext.correctedResolutionScope(calleeExpression) ?: return descriptors
 
-        if (importDeclarations) {
-            val importableDescriptors = descriptors.filter { it.canBeReferencedViaImport() }
+        if (descriptorsToImport.isNotEmpty()) {
             resolutionScope = ChainedScope(resolutionScope.getContainingDeclaration(), "Scope with explicitly imported descriptors",
-                                           ExplicitImportsScope(importableDescriptors), resolutionScope)
+                                           ExplicitImportsScope(descriptorsToImport), resolutionScope)
         }
 
         val dataFlowInfo = bindingContext.getDataFlowInfo(calleeExpression)

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

@@ -226,8 +226,7 @@ abstract class CompletionSessionBase(protected val configuration: CompletionSess
     protected fun getTopLevelExtensions(): Collection<CallableDescriptor> {
         val extensions = indicesHelper.getCallableTopLevelExtensions({ prefixMatcher.prefixMatches(it) }, reference!!.expression)
         //TODO: it filters out too much
-        //TODO: not filtered out dominated by members
-        return ShadowedDeclarationsFilter(bindingContext, moduleDescriptor, project, importDeclarations = true).filter(extensions, reference.expression)
+        return ShadowedDeclarationsFilter(bindingContext, moduleDescriptor, project).filterNonImported(extensions, referenceVariants, reference.expression)
     }
 
     protected fun addAllClasses(kindFilter: (ClassKind) -> Boolean) {

idea/idea-completion/testData/basic/multifile/PreferMemberToExtension/PreferMemberToExtension.dependency.kt

@@ -0,0 +1,3 @@
+package dependency
+
+fun Any.xxx(): Int = 1

idea/idea-completion/testData/basic/multifile/PreferMemberToExtension/PreferMemberToExtension.kt

@@ -0,0 +1,14 @@
+package ppp
+
+import dependency.*
+
+class C {
+    private fun xxx() {}
+
+    fun foo() {
+        xx<caret>
+    }
+}
+
+// EXIST: { lookupString: "xxx", itemText: "xxx", tailText: "()", typeText: "Unit" }
+// NOTHING_ELSE

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/MultiFileJvmBasicCompletionTestGenerated.java

@@ -215,6 +215,12 @@ public class MultiFileJvmBasicCompletionTestGenerated extends AbstractMultiFileJ
         doTest(fileName);
     }
 
+    @TestMetadata("PreferMemberToExtension")
+    public void testPreferMemberToExtension() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("idea/idea-completion/testData/basic/multifile/PreferMemberToExtension/");
+        doTest(fileName);
+    }
+
     @TestMetadata("PreferMoreSpecificExtension1")
     public void testPreferMoreSpecificExtension1() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("idea/idea-completion/testData/basic/multifile/PreferMoreSpecificExtension1/");