Revised the ProGuard rules and added tests on R8

build.gradle.kts

@@ -21,14 +21,7 @@ plugins {
 
 repositories {
     mavenCentral()
-    maven("https://maven.pkg.jetbrains.space/kotlin/p/dokka/dev")
-    // kotlin-dev with space redirector
-    maven("https://cache-redirector.jetbrains.com/maven.pkg.jetbrains.space/kotlin/p/kotlin/dev")
     maven("https://redirector.kotlinlang.org/maven/dev")
-    // For Dokka that depends on kotlinx-html
-    maven("https://maven.pkg.jetbrains.space/public/p/kotlinx-html/maven")
-    // For local development
-    mavenLocal()
 }
 
 // == common projects settings setup
@@ -60,14 +53,13 @@ allprojects {
     }
     repositories {
         mavenCentral()
-        maven("https://cache-redirector.jetbrains.com/maven.pkg.jetbrains.space/kotlin/p/kotlin/dev")
         maven("https://redirector.kotlinlang.org/maven/dev")
     }
 }
 
 // == BCV setup ==
 apiValidation {
-    ignoredProjects.addAll(listOf("benchmark", "guide", "kotlinx-serialization", "kotlinx-serialization-json-tests"))
+    ignoredProjects.addAll(listOf("benchmark", "guide", "kotlinx-serialization", "kotlinx-serialization-json-tests", "proguard-rules-test"))
     @OptIn(ExperimentalBCVApi::class)
     klib {
         enabled = true
@@ -163,6 +155,7 @@ val unpublishedProjects
         "guide",
         "kotlinx-serialization-json-tests",
         "proto-test-model",
+        "proguard-rules-test",
     )
 val excludedFromBomProjects get() = unpublishedProjects + "kotlinx-serialization-bom"
 

buildSrc/build.gradle.kts

@@ -26,16 +26,8 @@ repositories {
         maven("https://oss.sonatype.org/content/repositories/snapshots")
     }
 
-    // kotlin-dev with space redirector
-    maven("https://cache-redirector.jetbrains.com/maven.pkg.jetbrains.space/kotlin/p/kotlin/dev")
-    maven("https://redirector.kotlinlang.org/maven/dev")
-
-    maven("https://maven.pkg.jetbrains.space/kotlin/p/dokka/dev")
-    // For Dokka that depends on kotlinx-html
-    maven("https://maven.pkg.jetbrains.space/public/p/kotlinx-html/maven")
-
     mavenCentral()
-    mavenLocal()
+    maven("https://redirector.kotlinlang.org/maven/dev")
 }
 
 kotlin {

buildSrc/src/main/kotlin/Java9Modularity.kt

@@ -175,6 +175,7 @@ object Java9Modularity {
 
             val taskKotlinLanguageVersion = compilerOptions.languageVersion.orElse(KotlinVersion.DEFAULT)
             @OptIn(InternalKotlinGradlePluginApi::class)
+            @Suppress("DEPRECATION")
             if (taskKotlinLanguageVersion.get() < KotlinVersion.KOTLIN_2_0) {
                 // part of work-around for https://youtrack.jetbrains.com/issue/KT-60541
                 @Suppress("INVISIBLE_MEMBER")

buildSrc/src/main/kotlin/global-compiler-options.gradle.kts

@@ -33,15 +33,7 @@ tasks.withType(KotlinCompilationTask::class).configureEach {
                 null -> true // Werror is enabled by default
                 else -> throw GradleException("Invalid kotlin_Werror_override value. Use 'enable' or 'disable'")
             }
-
             allWarningsAsErrors = werrorEnabled
-            // Add extra compiler options when -Werror is disabled
-            if (!werrorEnabled) {
-                freeCompilerArgs.addAll(
-                    "-Wextra",
-                    "-Xuse-fir-experimental-checkers"
-                )
-            }
         }
     }
 }
@@ -58,4 +50,4 @@ tasks.withType<KotlinCompilationTask<*>>().configureEach {
         logger.info("Added Kotlin compiler flags: ${compilerOptions.freeCompilerArgs.get().joinToString(", ")}")
         logger.info("allWarningsAsErrors=${compilerOptions.allWarningsAsErrors.get()}")
     }
-}
+}

buildSrc/src/main/kotlin/kover-conventions.gradle.kts

@@ -47,6 +47,6 @@ kover {
 }
 
 
-val uncoveredProjects get() = setOf(":kotlinx-serialization-bom", ":benchmark", ":guide")
+val uncoveredProjects get() = setOf(":kotlinx-serialization-bom", ":benchmark", ":guide", ":proguard-rules-test")
 // map: variant name -> project path
 val projectsForCoverageVerification get() = mapOf("core" to ":kotlinx-serialization-core", "json" to ":kotlinx-serialization-json", "jsonOkio" to ":kotlinx-serialization-json-okio", "cbor" to ":kotlinx-serialization-cbor", "hocon" to ":kotlinx-serialization-hocon", "properties" to ":kotlinx-serialization-properties", "protobuf" to ":kotlinx-serialization-protobuf", "io" to ":kotlinx-serialization-json-io")

core/jvmMain/src/kotlinx/serialization/internal/Platform.kt

@@ -77,12 +77,20 @@ private fun <T: Any> Class<T>.findInNamedCompanion(vararg args: KSerializer<Any?
     }
 }
 
-private fun <T: Any> Class<T>.findNamedCompanionByAnnotation(): Any? {
-    val companionClass = declaredClasses.firstOrNull { clazz ->
-        clazz.getAnnotation(NamedCompanion::class.java) != null
+private fun <T : Any> Class<T>.findNamedCompanionByAnnotation(): Any? {
+    // search static field with type marked by kotlinx.serialization.internal.NamedCompanion - it's the companion
+    // declaredClasses after R8 even if `-keepattributes InnerClasses, EnclosingMethod` is specified, so we use declaredFields
+    val field = declaredFields.firstOrNull { field ->
+        Modifier.isStatic(field.modifiers) && field.type.getAnnotation(NamedCompanion::class.java) != null
     } ?: return null
 
-    return companionOrNull(companionClass.simpleName)
+    // short version of companionOrNull()
+    return try {
+        field.isAccessible = true
+        field.get(null)
+    } catch (e: Throwable) {
+        null
+    }
 }
 
 private fun <T: Any> Class<T>.isNotAnnotated(): Boolean {

integration-test/build.gradle.kts

@@ -20,7 +20,6 @@ plugins {
 
 repositories {
     mavenCentral()
-    maven("https://cache-redirector.jetbrains.com/maven.pkg.jetbrains.space/kotlin/p/kotlin/dev")
     maven("https://redirector.kotlinlang.org/maven/dev")
     mavenLocal {
         mavenContent {

integration-test/settings.gradle.kts

@@ -17,7 +17,6 @@ pluginManagement {
     repositories {
         mavenCentral()
         maven("https://plugins.gradle.org/m2/")
-        maven("https://cache-redirector.jetbrains.com/maven.pkg.jetbrains.space/kotlin/p/kotlin/dev")
         maven("https://redirector.kotlinlang.org/maven/dev")
         mavenLocal()
     }

rules/common.pro

@@ -1,15 +1,13 @@
-# Keep `Companion` object fields of serializable classes.
+# Keep `Companion` object field of serializable classes.
 # This avoids serializer lookup through `getDeclaredClasses` as done for named companion objects.
--if @kotlinx.serialization.Serializable class **
--keepclassmembers class <1> {
-    static <1>$* Companion;
-}
+ -keepclassmembers @kotlinx.serialization.Serializable class ** {
+    static ** Companion;
+ }
 
 # Keep names for named companion object from obfuscation
 # Names of a class and of a field are important in lookup of named companion in runtime
--keepnames @kotlinx.serialization.internal.NamedCompanion class *
 -if @kotlinx.serialization.internal.NamedCompanion class *
--keepclassmembernames class * {
+-keepclassmembers class * {
     static <1> *;
 }
 
@@ -36,7 +34,6 @@
 # Don't print notes about potential mistakes or omissions in the configuration for kotlinx-serialization classes
 # See also https://github.com/Kotlin/kotlinx.serialization/issues/1900
 -dontnote kotlinx.serialization.**
-
 # Serialization core uses `java.lang.ClassValue` for caching inside these specified classes.
 # If there is no `java.lang.ClassValue` (for example, in Android), then R8/ProGuard will print a warning.
 # However, since in this case they will not be used, we can disable these warnings

rules/r8.pro

@@ -11,6 +11,10 @@
  -if @kotlinx.serialization.Serializable class **
  -keep, allowshrinking, allowoptimization, allowobfuscation, allowaccessmodification class <1>
 
+# Rule to save runtime annotations on named companion class.
+# If the R8 full mode is used, annotations are removed from classes-files.
+-if @kotlinx.serialization.internal.NamedCompanion class *
+-keep, allowshrinking, allowoptimization, allowobfuscation, allowaccessmodification class <1>
 
 # Rule to save INSTANCE field and serializer function for Kotlin serializable objects.
 #