feat: add Kotlin 2.1.21 release info (#4817)

* feat: add Kotlin 2.1.21 release info

* feat: 2.1.21 doc update (#4812)

* update: xcode support

* chore: cinterop issue

* chore: fix Gradle max support

---------

Co-authored-by: alepedroza <[email protected]>

* chore: Andrey review

* update: fix for java-test-fixtures plugin in 2.1.21

* chore: fix dates

---------

Co-authored-by: Danil Pavlov <[email protected]>
Co-authored-by: Sarah Haggarty <[email protected]>

Author: 3 people

data/releases.yml

@@ -1,5 +1,5 @@
 url: https://github.com/JetBrains/kotlin/releases
 
 latest:
-  version: 2.1.20
-  url: https://github.com/JetBrains/kotlin/releases/tag/v2.1.20
+  version: 2.1.21
+  url: https://github.com/JetBrains/kotlin/releases/tag/v2.1.21

docs/topics/eap.md

@@ -63,14 +63,4 @@ In this channel, you can also get notifications about new EAP builds.
             <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.2.0-Beta2">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.2.0-Beta2</a>.</p>
         </td>
     </tr>
-    <tr>
-        <td><strong>2.1.21-RC2</strong>
-            <p>Released: <strong>May 1, 2025</strong></p>
-            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.21-RC2" target="_blank">Release on GitHub</a></p>
-        </td>
-        <td>
-            <p>A bug fix release for Kotlin 2.1.20.</p>
-            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.21-RC2">changelog</a>.</p>
-        </td>
-    </tr> 
 </table>

docs/topics/multiplatform/multiplatform-compatibility-guide.md

@@ -18,14 +18,15 @@ the Kotlin version you have in your projects, for example:
 When configuring your project, check the compatibility of a particular version of the Kotlin Multiplatform Gradle plugin
 (same as the Kotlin version in your project) with Gradle, Xcode, and Android Gradle plugin versions:
 
-| Kotlin Multiplatform plugin version | Gradle                                | Android Gradle plugin           | Xcode   |
-|-------------------------------------|---------------------------------------|---------------------------------|---------|
-| 2.1.20                              | %minGradleVersion%–%maxGradleVersion% | 7.4.2–%maxAndroidGradleVersion% | %xcode% |
-| 2.1.0–2.1.10                        | 7.6.3-8.10*                           | 7.4.2–8.7.2                     | 16.0    |
-| 2.0.21                              | 7.5-8.8*                              | 7.4.2–8.5                       | 16.0    |
-| 2.0.20                              | 7.5-8.8*                              | 7.4.2–8.5                       | 15.3    |
-| 2.0.0                               | 7.5-8.5                               | 7.4.2–8.3                       | 15.3    |
-| 1.9.20                              | 7.5-8.1.1                             | 7.4.2–8.2                       | 15.0    |
+| Kotlin Multiplatform plugin version | Gradle                                | Android Gradle plugin                               | Xcode   |
+|-------------------------------------|---------------------------------------|-----------------------------------------------------|---------|
+| 2.1.21                              | %minGradleVersion%–%maxGradleVersion% | %minAndroidGradleVersion%–%maxAndroidGradleVersion% | %xcode% |
+| 2.1.20                              | 7.6.3–8.11                            | 7.4.2–8.7.2                                         | 16.0    |
+| 2.1.0–2.1.10                        | 7.6.3-8.10*                           | 7.4.2–8.7.2                                         | 16.0    |
+| 2.0.21                              | 7.5-8.8*                              | 7.4.2–8.5                                           | 16.0    |
+| 2.0.20                              | 7.5-8.8*                              | 7.4.2–8.5                                           | 15.3    |
+| 2.0.0                               | 7.5-8.5                               | 7.4.2–8.3                                           | 15.3    |
+| 1.9.20                              | 7.5-8.1.1                             | 7.4.2–8.2                                           | 15.0    |
 
 > *Kotlin 2.0.20–2.0.21 and Kotlin 2.1.0–2.1.10 are fully compatible with Gradle up to 8.6.
 > Gradle versions 8.7–8.10 are also supported, with only one exception: If you use the Kotlin Multiplatform Gradle plugin,
@@ -77,6 +78,10 @@ Starting with Gradle 8.7, the Application plugin will no longer work with the Ko
 If you want to use both the Kotlin Multiplatform Gradle plugin and other Gradle plugins for
 Java in your multiplatform project, see [Deprecated compatibility with Kotlin Multiplatform Gradle plugin and Java plugins](multiplatform-compatibility-guide.md#deprecated-compatibility-with-kotlin-multiplatform-gradle-plugin-and-gradle-java-plugins).
 
+If you use the [Java test fixtures](https://docs.gradle.org/current/userguide/java_testing.html#sec:java_test_fixtures) Gradle plugin with Kotlin 2.1.20
+and a Gradle version higher than 8.7, the plugin doesn't work. Instead, upgrade to [Kotlin 2.1.21](releases.md#release-details)
+where this issue is resolved.
+
 If you run into any issues, report them in our [issue tracker](https://kotl.in/issue) or ask for help in our [public Slack channel](https://kotlinlang.slack.com/archives/C19FD9681).
 
 **When do the changes take effect?**

docs/topics/releases.md

@@ -104,6 +104,16 @@ The following table lists details of the latest Kotlin releases:
         <th>Build info</th>
         <th>Build highlights</th>
     </tr>
+    <tr>
+        <td><strong>2.1.21</strong>
+            <p>Released: <strong>May 13, 2025</strong></p>
+            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.21" target="_blank">Release on GitHub</a></p>
+        </td>
+        <td>
+            <p>A bug fix release for Kotlin 2.1.20.</p>
+            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.21">changelog</a>.</p>
+        </td>
+    </tr> 
    <tr>
         <td><strong>2.1.20</strong>
             <p>Released: <strong>March 20, 2025</strong></p>

docs/topics/whatsnew/whatsnew2120.md

@@ -6,7 +6,7 @@ The Kotlin 2.1.20 release is here! Here are the main highlights:
 
 * **K2 compiler updates**: [updates to the new kapt and Lombok plugins](#kotlin-k2-compiler)
 * **Kotlin Multiplatform**: [new DSL to replace Gradle's Application plugin](#kotlin-multiplatform-new-dsl-to-replace-gradle-s-application-plugin)
-* **Kotlin/Native**: [new inlining optimization](#kotlin-native-new-inlining-optimization)
+* **Kotlin/Native**: [support for Xcode 16.3 and a new inlining optimization](#kotlin-native)
 * **Kotlin/Wasm**: [default custom formatters, support for DWARF, and migration to Provider API](#kotlin-wasm)
 * **Gradle support**: [compatibility with Gradle's Isolated Projects and custom publication variants](#gradle)
 * **Standard library**: [common atomic types, improved UUID support, and new time-tracking functionality](#standard-library)
@@ -119,7 +119,17 @@ plugin is applied on the first `executable {}` block.
 
 If you run into any issues, report them in our [issue tracker](https://kotl.in/issue) or let us know in our [public Slack channel](https://kotlinlang.slack.com/archives/C19FD9681).
 
-## Kotlin/Native: new inlining optimization
+## Kotlin/Native
+
+### Support for Xcode 16.3
+
+Starting with Kotlin **2.1.21**, the Kotlin/Native compiler supports Xcode 16.3 – the latest stable version of Xcode.
+Feel free to update your Xcode and continue working on your Kotlin projects for Apple operating systems.
+
+The 2.1.21 release also fixes the related [cinterop issue](https://youtrack.jetbrains.com/issue/KT-75781/) that caused
+compilation failures in Kotlin Multiplatform projects.
+
+### New inlining optimization
 <primary-label ref="experimental-opt-in"/>
 
 Kotlin 2.1.20 introduces a new inlining optimization pass, which comes before the actual code generation phase.
@@ -551,9 +561,10 @@ alongside the plugin, due to an option being effectively set twice.
 
 ## Breaking changes and deprecations
 
-* To align Kotlin Multiplatform with upcoming changes in Gradle, we are phasing out the `withJava()` function.
-  [Java source sets are now created by default](multiplatform-compatibility-guide.md#java-source-sets-created-by-default).
 
+* To align Kotlin Multiplatform with upcoming changes in Gradle, we are phasing out the `withJava()` function.
+  [Java source sets are now created by default](multiplatform-compatibility-guide.md#java-source-sets-created-by-default). If you use the [Java test fixtures](https://docs.gradle.org/current/userguide/java_testing.html#sec:java_test_fixtures) Gradle plugin,
+  upgrade directly to [Kotlin 2.1.21](releases.md#release-details) to avoid compatibility issues.
 * The JetBrains team is proceeding with the deprecation of the `kotlin-android-extensions` plugin. If you try to use it
   in your project, you'll now get a configuration error, and no plugin code will be executed.
 

docs/v.list

@@ -5,9 +5,9 @@
 <vars>
 
     <!-- Kotlin -->
-    <var name="kotlinVersion" value="2.1.20" type="string"/>
-    <var name="kotlinReleaseDate" value="March 20, 2025" type="string"/>
-    <var name="kotlinLatestUrl" value="https://github.com/JetBrains/kotlin/releases/tag/v2.1.20" type="string"/>
+    <var name="kotlinVersion" value="2.1.21" type="string"/>
+    <var name="kotlinReleaseDate" value="May 13, 2025" type="string"/>
+    <var name="kotlinLatestUrl" value="https://github.com/JetBrains/kotlin/releases/tag/v2.1.21" type="string"/>
     <var name="kotlinLatestWhatsnew" value="whatsnew2120.md" type="string"/>
 
     <var name="languageVersion" value="2.1" type="string"/>
@@ -35,7 +35,7 @@
 
     <!-- Gradle, KGP, AGP -->
     <var name="minGradleVersion" value="7.6.3" type="string"/>
-    <var name="maxGradleVersion" value="8.11" type="string"/>
+    <var name="maxGradleVersion" value="8.12.1" type="string"/>
 
     <var name="minAndroidGradleVersion" value="7.3.1" type="string"/>
     <var name="maxAndroidGradleVersion" value="8.7.2" type="string"/>
@@ -67,6 +67,6 @@
          value="2.0.0"
          type="string"/>
 
-    <var name="xcode" value="16.0" type="string"/>
+    <var name="xcode" value="16.3" type="string"/>
 
 </vars>