Fixed reference search of implicitly imported top-level functions

idea/idea-analysis/src/org/jetbrains/kotlin/idea/search/ideaExtensions/KotlinReferenceScopeOptimizer.kt

@@ -15,6 +15,8 @@ import com.intellij.psi.search.UsageSearchContext
 import org.jetbrains.kotlin.fileClasses.javaFileFacadeFqName
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.idea.search.excludeFileTypes
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.isSubpackageOf
 import org.jetbrains.kotlin.psi.KtCallableDeclaration
 import org.jetbrains.kotlin.psi.KtFile
 
@@ -26,10 +28,13 @@ class KotlinReferenceScopeOptimizer : ScopeOptimizer {
         return null
     }
 
+    // package "kotlin" and some of its subpackages may be imported by default
+    private val kotlinPackage = FqName.fromSegments(listOf("kotlin"))
+
     private fun getRestrictedScopeForTopLevelCallable(callable: KtCallableDeclaration): GlobalSearchScope? {
         val useScope = callable.useScope as? GlobalSearchScope ?: return null
         val file = callable.parent as KtFile
-        val packageName = file.packageFqName.takeUnless { it.isRoot } ?: return null
+        val packageName = file.packageFqName.takeUnless { it.isRoot || it.isSubpackageOf(kotlinPackage) } ?: return null
         val project = file.project
         val cacheManager = CacheManager.SERVICE.getInstance(project)
 
@@ -37,7 +42,6 @@ class KotlinReferenceScopeOptimizer : ScopeOptimizer {
         val javaScope = GlobalSearchScope.getScopeRestrictedByFileTypes(useScope, JavaFileType.INSTANCE)
         val restScope = useScope.excludeFileTypes(KotlinFileType.INSTANCE, JavaFileType.INSTANCE) as GlobalSearchScope
 
-        //TODO: use all components of package name?
         val shortPackageName = packageName.shortName().identifier
         val kotlinFiles = cacheManager.getVirtualFilesWithWord(shortPackageName, UsageSearchContext.IN_CODE, kotlinScope, true)
 

idea/idea-analysis/src/org/jetbrains/kotlin/idea/search/ideaExtensions/KotlinReferenceScopeOptimizer.kt.201

@@ -23,10 +23,13 @@ class KotlinReferenceScopeOptimizer : ScopeOptimizer {
         return null
     }
 
+    // package "kotlin" and some of its subpackages may be imported by default
+    private val kotlinPackage = FqName.fromSegments(listOf("kotlin"))
+
     private fun getRestrictedScopeForTopLevelCallable(callable: KtCallableDeclaration): GlobalSearchScope? {
         val useScope = callable.useScope as? GlobalSearchScope ?: return null
         val file = callable.parent as KtFile
-        val packageName = file.packageFqName.takeUnless { it.isRoot } ?: return null
+        val packageName = file.packageFqName.takeUnless { it.isRoot || it.isSubpackageOf(kotlinPackage) } ?: return null
         val project = file.project
         val searchHelper = PsiSearchHelper.getInstance(project)
 

idea/testData/findUsages/kotlin/findFunctionUsages/stdlibExtensionUsages.0.kt

@@ -0,0 +1,13 @@
+// PSI_ELEMENT: org.jetbrains.kotlin.psi.KtNamedFunction
+// OPTIONS: usages
+package sample
+
+fun foo(list: List<String>) {
+    val s = list.<caret>joinToString()
+}
+
+fun bar(list: List<Int>) {
+    val s = list.joinToString()
+}
+
+

idea/testData/findUsages/kotlin/findFunctionUsages/stdlibExtensionUsages.results.txt

@@ -0,0 +1,2 @@
+Function call 10 val s = list.joinToString()
+Function call 6 val s = list.joinToString()

idea/tests/org/jetbrains/kotlin/findUsages/FindUsagesTestGenerated.java

@@ -754,6 +754,11 @@ public class FindUsagesTestGenerated extends AbstractFindUsagesTest {
                 runTest("idea/testData/findUsages/kotlin/findFunctionUsages/objectExpressionMemberInTopLevel.0.kt");
             }
 
+            @TestMetadata("stdlibExtensionUsages.0.kt")
+            public void testStdlibExtensionUsages() throws Exception {
+                runTest("idea/testData/findUsages/kotlin/findFunctionUsages/stdlibExtensionUsages.0.kt");
+            }
+
             @TestMetadata("synthesizedFunction.0.kt")
             public void testSynthesizedFunction() throws Exception {
                 runTest("idea/testData/findUsages/kotlin/findFunctionUsages/synthesizedFunction.0.kt");