KT-38003 works for Java implementations of extension method

idea/src/org/jetbrains/kotlin/idea/slicer/OutflowSlicer.kt

@@ -19,10 +19,7 @@ import org.jetbrains.kotlin.idea.findUsages.handlers.SliceUsageProcessor
 import org.jetbrains.kotlin.idea.search.declarationsSearch.forEachOverridingElement
 import org.jetbrains.kotlin.idea.search.ideaExtensions.KotlinReadWriteAccessDetector
 import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.psiUtil.getNonStrictParentOfType
-import org.jetbrains.kotlin.psi.psiUtil.getParentOfTypeAndBranch
-import org.jetbrains.kotlin.psi.psiUtil.isAncestor
-import org.jetbrains.kotlin.psi.psiUtil.parameterIndex
+import org.jetbrains.kotlin.psi.psiUtil.*
 import org.jetbrains.kotlin.resolve.source.getPsi
 
 class OutflowSlicer(
@@ -69,19 +66,20 @@ class OutflowSlicer(
             //TODO: expect/actual
 
             val callable = variable.ownerFunction as? KtCallableDeclaration
+            val parameterIndex = variable.parameterIndex()
             callable?.forEachOverridingElement(scope = analysisScope) { _, overridingMember ->
                 when (overridingMember) {
                     is KtCallableDeclaration -> {
                         val parameters = overridingMember.valueParameters
                         check(parameters.size == callable.valueParameters.size)
-                        parameters[variable.parameterIndex()].passToProcessor()
+                        parameters[parameterIndex].passToProcessor()
                     }
 
                     is PsiMethod -> {
                         val parameters = overridingMember.parameterList.parameters
-                        check(parameters.size == callable.valueParameters.size)
-                        parameters[variable.parameterIndex()].passToProcessor()
-                        processor.process(JavaSliceUsage.createRootUsage(parameters[variable.parameterIndex()], parentUsage.params))
+                        val shift = if (callable.receiverTypeReference != null) 1 else 0
+                        check(parameters.size == callable.valueParameters.size + shift)
+                        processor.process(JavaSliceUsage.createRootUsage(parameters[parameterIndex + shift], parentUsage.params))
                     }
 
                     else -> {} // not supported

idea/testData/slicer/outflow/abstractExtensionMethodParameter.java

@@ -0,0 +1,6 @@
+class JavaClass implements I {
+    @Override
+    public void foo(int receiver, Object p) {
+        System.out.println(p);
+    }
+}

idea/testData/slicer/outflow/abstractExtensionMethodParameter.kt

@@ -0,0 +1,15 @@
+// FLOW: OUT
+
+interface I {
+    fun Int.foo(p: Any)
+}
+
+class C1 : I {
+    override fun Int.foo(p: Any) {
+        println(p) // this usage will be shown twice due to bug in Java implementation: https://youtrack.jetbrains.com/issue/IDEA-236958
+    }
+}
+
+fun I.bar(s: String) {
+    1.foo(<caret>s)
+}

idea/testData/slicer/outflow/abstractExtensionMethodParameter.results.txt

@@ -0,0 +1,7 @@
+14 1.foo(<bold>s</bold>)
+4 	fun Int.foo(<bold>p: Any</bold>)
+3 		public void foo(int receiver, Object <bold>p</bold>) {
+4 			System.out.println(<bold>p</bold>);
+9 			println(<bold>p</bold>) // this usage will be shown twice due to bug in Java implementation: https://youtrack.jetbrains.com/issue/IDEA-236958
+8 		override fun Int.foo(<bold>p: Any</bold>) {
+9 			DUPLICATE: println(<bold>p</bold>) // this usage will be shown twice due to bug in Java implementation: https://youtrack.jetbrains.com/issue/IDEA-236958

idea/tests/org/jetbrains/kotlin/idea/slicer/SlicerTreeTestGenerated.java

@@ -348,6 +348,11 @@ public class SlicerTreeTestGenerated extends AbstractSlicerTreeTest {
         runTest("idea/testData/slicer/inflow/whenExpression.kt");
     }
 
+    @TestMetadata("outflow/abstractExtensionMethodParameter.kt")
+    public void testOutflow_AbstractExtensionMethodParameter() throws Exception {
+        runTest("idea/testData/slicer/outflow/abstractExtensionMethodParameter.kt");
+    }
+
     @TestMetadata("outflow/abstractMethodParameter1.kt")
     public void testOutflow_AbstractMethodParameter1() throws Exception {
         runTest("idea/testData/slicer/outflow/abstractMethodParameter1.kt");