Supported usages as destructuring declaration for other class

idea/idea-analysis/src/org/jetbrains/kotlin/idea/search/usagesSearch/destructuringDeclarationUsages.kt

@@ -44,6 +44,7 @@ import org.jetbrains.kotlin.idea.util.fuzzyExtensionReceiverType
 import org.jetbrains.kotlin.idea.util.toFuzzyType
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.*
+import org.jetbrains.kotlin.resolve.dataClassUtils.getComponentIndex
 import org.jetbrains.kotlin.resolve.descriptorUtil.isExtension
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.util.isValidOperator
@@ -278,7 +279,21 @@ private class Processor(
         //TODO: what about Scala and other JVM-languages?
         val declarationUsageScope = GlobalSearchScope.projectScope(declaration.project).restrictToKotlinSources()
         ReferencesSearch.search(declaration, declarationUsageScope).forEach { reference ->
-            (reference.element as? KtReferenceExpression)?.let { processSuspiciousExpression(it) }
+            if (reference is KtDestructuringDeclarationReference) { // declaration usage in form of destructuring declaration
+                val entries = reference.element.entries
+                val componentIndex = when (declaration) {
+                    is KtParameter -> declaration.dataClassComponentFunction()?.name?.asString()?.let { getComponentIndex(it) }
+                    is KtFunction -> declaration.name?.let { getComponentIndex(it) }
+                    //TODO: java component functions (see KT-13605)
+                    else -> null
+                }
+                if (componentIndex != null && componentIndex <= entries.size) {
+                    processDeclarationOfTypeWithDataClass(entries[componentIndex - 1])
+                }
+            }
+            else {
+                (reference.element as? KtReferenceExpression)?.let { processSuspiciousExpression(it) }
+            }
         }
     }
 
@@ -313,8 +328,6 @@ private class Processor(
                         }
                     }
                 }
-
-            //TODO: entry of data type
             }
         }
     }

idea/testData/findUsages/kotlin/conventions/components/dataClass.0.java

@@ -8,4 +8,4 @@ class JavaClass {
     }
 
     public void takeA(A a){}
-}
+}

idea/testData/findUsages/kotlin/conventions/components/dataClass.2.kt

@@ -1,6 +1,6 @@
 import pack.A
 
-fun test(javaClass: JavaClass) {
+fun test(javaClass: JavaClass, javaClass2: JavaClass2) {
     val a = A(1, "2", Any())
     a.n
     a.component1()

idea/testData/findUsages/kotlin/conventions/components/dataClass.3.kt

@@ -0,0 +1,16 @@
+package pack
+
+data class B(val a: A, val n: Int)
+
+class C {
+    operator fun component1(): A = TODO()
+    operator fun component2() = 0
+}
+
+fun f(b: B, c: C) {
+    val (a, n) = b
+    val (x, y, z) = a
+
+    val (a1, n1) = c
+    val (x1, y1, z1) = a1
+}

idea/testData/findUsages/kotlin/conventions/components/dataClass.results.txt

@@ -12,4 +12,6 @@
 [dataClass.2.kt] Value read 33 val (x, y) = list[0]
 [dataClass.2.kt] Value read 5 a.n
 [dataClass.2.kt] Value read 8 val (x, y, z) = a
-[dataClass.2.kt] Value read 9 val (x1, y1, z1) = f()
+[dataClass.2.kt] Value read 9 val (x1, y1, z1) = f()
+[dataClass.3.kt] Value read 12 val (x, y, z) = a
+[dataClass.3.kt] Value read 15 val (x1, y1, z1) = a1