From 4d21309f845b90efcef24996045bce97ac2a9148 Mon Sep 17 00:00:00 2001
From: Atul Gupta <atlgpt17@gmail.com>
Date: Sat, 27 May 2023 21:07:32 +0530
Subject: [PATCH] UnusedPrivateProperty: Fix false postive by ignoring data
 classes (#6151)

---
 .../rules/style/UnusedPrivateProperty.kt      |  9 +++++-
 .../rules/style/UnusedPrivatePropertySpec.kt  | 31 +++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivateProperty.kt b/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivateProperty.kt
index 53a5ccdd2ec..61c322f64ca 100644
--- a/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivateProperty.kt
+++ b/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivateProperty.kt
@@ -14,6 +14,7 @@ import io.gitlab.arturbosch.detekt.api.internal.Configuration
 import io.gitlab.arturbosch.detekt.rules.isActual
 import io.gitlab.arturbosch.detekt.rules.isExpect
 import org.jetbrains.kotlin.com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.psi.KtClass
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi.KtImportDirective
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
@@ -108,11 +109,17 @@ private class UnusedPrivatePropertyVisitor(private val allowedNames: Regex) : De
         constructor.valueParameters
             .filter {
                 (it.isPrivate() || (!it.hasValOrVar() && !constructor.isActual())) &&
-                    it.containingClassOrObject?.isExpect() == false
+                    it.containingClassOrObject?.isExpect() == false &&
+                    isConstructorForDataOrValueClass(constructor).not()
             }
             .forEach { maybeAddUnusedProperty(it) }
     }
 
+    private fun isConstructorForDataOrValueClass(constructor: PsiElement): Boolean {
+        val parent = constructor.parent as? KtClass ?: return false
+        return parent.isData() || parent.isValue() || parent.isInline()
+    }
+
     override fun visitSecondaryConstructor(constructor: KtSecondaryConstructor) {
         super.visitSecondaryConstructor(constructor)
         constructor.valueParameters.forEach { maybeAddUnusedProperty(it) }
diff --git a/detekt-rules-style/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivatePropertySpec.kt b/detekt-rules-style/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivatePropertySpec.kt
index 534b15e8c41..53a6810088c 100644
--- a/detekt-rules-style/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivatePropertySpec.kt
+++ b/detekt-rules-style/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnusedPrivatePropertySpec.kt
@@ -747,6 +747,37 @@ class UnusedPrivatePropertySpec(val env: KotlinCoreEnvironment) {
             """.trimIndent()
             assertThat(subject.lint(code)).isEmpty()
         }
+
+        @Test
+        fun `does not report unused private property in data class - #6142`() {
+            val code = """
+                data class Foo(
+                    private val foo: Int,
+                    private val bar: String,
+                )
+            """.trimIndent()
+            assertThat(subject.lint(code)).isEmpty()
+        }
+
+        @Test
+        fun `does not report unused private property in data class with named constructor`() {
+            val code = """
+                data class Foo constructor(
+                    private val foo: Int,
+                    private val bar: String,
+                )
+            """.trimIndent()
+            assertThat(subject.lint(code)).isEmpty()
+        }
+
+        @Test
+        fun `does not report unused private property in value or inline class`() {
+            val code = """
+                @JvmInline value class Foo(private val value: String)
+                inline class Bar(private val value: String)
+            """.trimIndent()
+            assertThat(subject.lint(code)).isEmpty()
+        }
     }
 
     @Nested