feat: Kotlin 2.3.0-RC release details (#5178)

Author: danil-pavlov

docs/kr.tree

@@ -22,7 +22,7 @@
         <toc-element hidden="true" topic="kotlin-tour-intermediate-libraries-and-apis.md"/>
     </toc-element>
     <toc-element toc-title="What's new in Kotlin">
-        <toc-element toc-title="Kotlin 2.3.0-Beta2" topic="whatsnew-eap.md"/>
+        <toc-element toc-title="Kotlin 2.3.0-RC" topic="whatsnew-eap.md"/>
         <toc-element toc-title="Kotlin 2.2.20" accepts-web-file-names="whatsnew.html" topic="whatsnew2220.md"/>
         <toc-element toc-title="Kotlin 2.2.0" topic="whatsnew22.md"/>
         <toc-element topic="compatibility-guide-22.md"/>

docs/topics/eap.md

@@ -52,13 +52,13 @@ In this channel, you can also get notifications about new EAP builds.
         <th>Build highlights</th>
     </tr>
     <tr>
-        <td><strong>2.3.0-Beta2</strong>
-            <p>Released: <strong>October 28, 2025</strong></p>
-            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.0-Beta2" target="_blank">Release on GitHub</a></p>
+        <td><strong>2.3.0-RC</strong>
+            <p>Released: <strong>November 18, 2025</strong></p>
+            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.0-RC" target="_blank">Release on GitHub</a></p>
         </td>
         <td>
             <p>A language release with previews of new features and tooling updates.</p>
-            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.0-Beta2">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.3.0-Beta2</a>.</p>
+            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.0-RC">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.3.0-RC</a>.</p>
         </td>
     </tr>
 </table>

docs/topics/whatsnew/whatsnew-eap.md

@@ -15,7 +15,7 @@ The Kotlin %kotlinEapVersion% release is out! Here are some details of this EAP
 
 * **Language**: [more stable and default features, a new checker for unused return values, and changes to context-sensitive resolution](#language).
 * **Kotlin/JVM**: [support for Java 25](#kotlin-jvm-support-for-java-25).
-* **Kotlin/Native**: [improved interop through Swift export and type checks on generic type boundaries enabled by default](#kotlin-native).
+* **Kotlin/Native**: [improved interop through Swift export](#kotlin-native-improved-interop-through-swift-export).
 * **Kotlin/Wasm**: [fully qualified names and new exception handling proposal enabled by default](#kotlin-wasm).
 * **Kotlin/JS**: [new experimental suspend function export and `LongArray` representation](#kotlin-js).
 * **Gradle**: [compatibility with Gradle 9.0 and a new API for registering generated sources](#gradle).
@@ -188,9 +188,7 @@ For details, see the full text of the current proposal in [KEEP](https://github.
 
 Starting with Kotlin %kotlinEapVersion%, the compiler can generate classes containing Java 25 bytecode.
 
-## Kotlin/Native
-
-### Improved interop through Swift export
+## Kotlin/Native: improved interop through Swift export
 <primary-label ref="experimental-general"/>
 
 Kotlin %kotlinEapVersion% further improves Kotlin interoperability with Swift through Swift export, adding support for
@@ -232,34 +230,13 @@ fun log(vararg messages: String)
 
 ```Swift
 // Swift
-func log(_ messages: String...)
+public func log(messages: Swift.String...)
 ```
 
 > Generic types in variadic function parameters are not supported yet.
 >
 {style="note"}
 
-### Type checks on generic type boundaries in debug mode
-
-Starting with Kotlin %kotlinEapVersion%, type checks on generic type boundaries are enabled by default in debug mode,
-helping you find errors related to unchecked casts earlier. This change improves safety and makes debugging of invalid
-generic casts more predictable across platforms.
-
-Previously, unchecked casts that led to heap pollution and violation of memory safety could go unnoticed in Kotlin/Native.
-Now, such cases consistently fail with a runtime cast error, similar to Kotlin/JVM or Kotlin/JS. For example:
-
-```kotlin
-fun main() {
-    val list = listOf("hello")
-    val x = (list as List<Int>)[0]
-    println(x) // Now throws a ClassCastException error
-}
-```
-
-This code used to print `6`; now it throws a `ClassCastException` error in debug mode, as expected.
-
-For more information, see [Type checks and casts](typecasts.md).
-
 ## Kotlin/Wasm
 
 ### Fully qualified names enabled by default
@@ -462,3 +439,13 @@ mappings for some functions, please report them to the [Google IssueTracker](htt
 >
 {style="note"}
 
+By default, the mapping file Gradle tasks run regardless of whether you enable the traces. If they cause problems in your
+build, you can disable the feature entirely. Add the following property in the `composeCompiler {}` block of your Gradle configuration:
+
+```kotlin
+composeCompiler {
+    includeComposeMappingFile.set(false)
+}
+```
+
+Please report any problems encountered to the [Google IssueTracker](https://issuetracker.google.com/issues/new?component=610764&template=1424126).

docs/v.list

@@ -14,8 +14,8 @@
     <var name="apiVersion" value="2.1"/>
 
     <!-- Kotlin EAP -->
-    <var name="kotlinEapVersion" value="2.3.0-Beta2"/>
-    <var name="kotlinEapReleaseDate" value="October 28, 2025"/>
+    <var name="kotlinEapVersion" value="2.3.0-RC"/>
+    <var name="kotlinEapReleaseDate" value="November 18, 2025"/>
 
     <!-- Libraries and Frameworks -->
     <var name="coroutinesVersion" value="1.10.2"/>