Kotlin: support 2.4.20-RC2 by andersfugmann · Pull Request #22404 · github/codeql

andersfugmann · 2026-08-21T11:44:17Z

Summary

Support Kotlin 2.4.20-RC2 in the Kotlin extractor. Kotlin 2.4.20 GA remains unsupported.

The implementation is split between release-driven compatibility changes and two observed RC2 behaviours. The release changelog explicitly removes remaining ComponentRegistrar usage (KT-85816) and applies @K1Deprecation to public K1 APIs (KT-86046). The RC2 compiler also gives generated interface forwarders synthetic source offsets and rejects the previous repeatable-annotation access path. The extractor adapts to those behaviours without changing query results.

Motivation for each change

Change	Motivation
Add standalone, embeddable, and standard-library RC2 artefacts	Build and test the extractor against the published `v2.4.20-RC2` compiler rather than an inferred compatible version.
Add an 2.4.20-specific `CompilerPluginRegistrar` implementation	`ComponentRegistrar` is absent from the 2.4.20 compiler, matching KT-85816. The existing registrar cannot be loaded because it implements both APIs.
Package the legacy `ComponentRegistrar` service only before 2.4.20	Older compilers still require the legacy service, while 2.4.20 fails if that service refers to the removed class. This keeps compatibility selection at the build boundary.
Opt in to `org.jetbrains.kotlin.K1Deprecation` from 2.4.20	The extractor still uses K1 compatibility APIs. KT-86046 makes the opt-in an error-level requirement in 2.4.20.
Reuse the `annotationClass` compatibility extension	2.4.20 rejects the previous IR parent access. The existing extension uses `constructedClass` and also compiles with the oldest supported Kotlin 1.8.0 compiler.
Assign fabricated interface forwarders the enclosing class location	2.4.20 reports synthetic offsets for these generated declarations. They have no direct source declaration, so the enclosing class is the stable location and preserves previous database and query output. This behaviour was observed during extraction and is not called out explicitly in the release changelog.
Make 2.4.20-RC2 the development and Kotlin 2 test default	Exercise the newly supported compiler in the normal Kotlin 2 suite.
Test 2.4.20 GA in the too-new diagnostic	Verify the intended RC2-only boundary directly.
Update documentation and the change note to 2.4.20-RC2	Avoid implying support for 2.4.20 GA.

Compatibility

Compiler variants before 2.4.20 retain their existing registrar and service packaging.
The K1 opt-in changes compilation only and does not change extracted data.
Repeatable annotation extraction uses the existing cross-version compatibility path.
Generated forwarders retain their previous observable locations. No fake-override, AST, expression-type, or inherited-interface-default expectations change.
Kotlin 2.4.20 GA and other prerelease spellings remain unsupported.

Validation

Built all 26 extractor variants: standalone and embeddable for every compiler version declared in VERSIONS
Ran ten representative tests for every supported compiler and applicable language mode: K1 for Kotlin 1.8 through 2.3, and K2 for Kotlin 2.0 through 2.4
Built standalone and embeddable 2.4.20-RC2 extractor variants
Built the oldest supported 1.8.0 extractor variant
Full Kotlin 2 suite passed in eight sequential shards with one test thread
Full Kotlin 1 suite passed with 2.3.20 in eight sequential shards with one test thread
All 36 Kotlin all-platform extraction tests passed in eight sequential shards
All 63 Kotlin all-platform QL integration tests passed in eight sequential shards
The published v2.4.20-RC2 compiler passed the Kotlin basic functionality extraction test
The too-new diagnostic test rejects 2.4.20 GA

No tests are disabled. The only changed generated expectation is the too-new diagnostic.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Kotlin 2.4.20-RC removes the remaining ComponentRegistrar API under KT-85816. Use an RC-specific registrar that only implements CompilerPluginRegistrar, and package the legacy ComponentRegistrar service only for older compilers. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Kotlin 2.4.20-RC marks public K1 APIs with K1Deprecation under KT-86046 and rejects the previous repeatable-annotation IR access path. Opt in to K1Deprecation for 2.4.20 and later, and use the existing annotationClass compatibility extension. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Kotlin 2.4.20-RC assigns synthetic source offsets to generated interface forwarders. Use the enclosing class location for each fabricated forwarder and its generated body and accesses, preserving existing database and query output. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace the previous 2.4.20-RC dependency set and compatibility marker with RC2 while preserving existing extraction output. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

andersfugmann · 2026-08-28T11:41:57Z

Bumped artifacts to Kotlin 2.4.20-RC2

Copilot

Copilot review overview

Review tier: Balanced
Findings: None

What changed in this PR

Adds preliminary Kotlin 2.4.20-RC2 extractor support while continuing to reject Kotlin 2.4.20 GA.

Changes:

Adds RC2 compiler dependencies and extractor variants.
Adapts compiler registration, annotations, and synthetic forwarder locations.
Updates defaults, diagnostics, documentation, and release notes.

File	Description
`MODULE.bazel`	Registers RC2 dependency repositories.
`java/ql/lib/change-notes/2026-08-21-kotlin-2.4.20.md`	Announces preliminary support.
`java/ql/integration-tests/kotlin/all-platforms/diagnostics/kotlin-version-too-new/fake-kotlinc-source/kotlin/KotlinVersion.java`	Tests the GA rejection boundary.
`java/ql/integration-tests/kotlin/all-platforms/diagnostics/kotlin-version-too-new/diagnostics.expected`	Updates the expected diagnostic.
`java/kotlin-extractor/versions.bzl`	Adds the RC2 extractor version.
`java/kotlin-extractor/src/main/kotlin/utils/versions/v_2_4_20-RC2/Kotlin2ComponentRegistrar.kt`	Implements the supported registrar API.
`java/kotlin-extractor/src/main/kotlin/MetaAnnotationSupport.kt`	Uses compatible annotation-class access.
`java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt`	Stabilizes generated forwarder locations.
`java/kotlin-extractor/dev/wrapper.py`	Makes RC2 the development default.
`java/kotlin-extractor/deps/kotlin-stdlib-2.4.20-RC2.jar`	Adds the RC2 standard library artifact.
`java/kotlin-extractor/deps/kotlin-compiler-embeddable-2.4.20-RC2.jar`	Adds the embeddable compiler artifact.
`java/kotlin-extractor/deps/kotlin-compiler-2.4.20-RC2.jar`	Adds the standalone compiler artifact.
`java/kotlin-extractor/BUILD.bazel`	Configures version-specific APIs and services.
`docs/codeql/reusables/supported-versions-compilers.rst`	Documents preliminary RC2 support.

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

…2.4.20rc

Keep the branch tip separate from the merge commit so semmle-code QLDoc checks compare against the merged CodeQL tree rather than the pre-merge first parent. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jketema

First round of comments. There is an RC3 btw.

jketema · 2026-09-02T13:08:09Z


   Eclipse compiler for Java (ECJ) [6]_",``.java``
-   Kotlin,"Kotlin 1.8.0 to 2.4.1\ *x*","kotlinc",``.kt``
+   Kotlin [13]_,"Kotlin 1.8.0 to 2.4.20-RC2","kotlinc",``.kt``


Footnotes should be ordered. I don't think we need a footnote though, as there's nothing really preliminary about this.

jketema · 2026-09-02T13:12:41Z

 public class KotlinVersion {

-  public static String CURRENT = "999.999.999";
+  public static String CURRENT = "2.4.20";


I understand why you changed this, but in the long run this seems non-ideal because we'll need to keep updating the test.

jketema · 2026-09-02T13:14:03Z

-    ) : Label<out DbCallable> =
-        forceExtractFunction(
+    ) : Label<out DbCallable> {
+        val sourceLoc = tw.getLocation(f.parentClassOrNull ?: f)


What breaks without the changes to this file?

jketema · 2026-09-02T13:16:09Z

@@ -0,0 +1,32 @@
+package com.github.codeql


This file basically mimics what older compilers supplied by default somehow?

github-actions Bot added documentation Java Kotlin labels Aug 21, 2026

andersfugmann force-pushed the andersfugmann/kotlin-2.4.20rc branch 7 times, most recently from f74d5b1 to 2fa6f32 Compare August 26, 2026 10:43

andersfugmann and others added 7 commits August 26, 2026 13:24

Kotlin: add 2.4.20-RC artifacts

93e6135

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Kotlin: enable 2.4.20-RC support

8b8b961

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Kotlin: make 2.4.20-RC the test default

f146aa6

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Kotlin: document preliminary 2.4.20-RC support

b9c81d5

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

andersfugmann force-pushed the andersfugmann/kotlin-2.4.20rc branch from 2fa6f32 to b9c81d5 Compare August 26, 2026 11:25

andersfugmann removed the Java label Aug 26, 2026

andersfugmann self-assigned this Aug 26, 2026

github-actions Bot added the Java label Aug 26, 2026

Kotlin: support 2.4.20-RC2

63553e3

Replace the previous 2.4.20-RC dependency set and compatibility marker with RC2 while preserving existing extraction output. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

andersfugmann changed the title ~~Kotlin: support 2.4.20-RC~~ Kotlin: support 2.4.20-RC2 Aug 28, 2026

andersfugmann marked this pull request as ready for review August 28, 2026 11:42

Copilot AI balanced review requested due to automatic review settings August 28, 2026 11:42

andersfugmann requested review from a team as code owners August 28, 2026 11:42

andersfugmann requested a review from a team as a code owner August 28, 2026 11:42

Copilot started reviewing on behalf of andersfugmann August 28, 2026 11:43 View session

Copilot AI reviewed Aug 28, 2026

View reviewed changes

andersfugmann mentioned this pull request Aug 28, 2026

Kotlin: cover 2.4.20 language features #22462

Draft

andersfugmann and others added 2 commits September 2, 2026 09:32

Merge remote-tracking branch 'origin/main' into andersfugmann/kotlin-…

05a4fe3

…2.4.20rc

Preserve the post-merge QLDoc baseline

b0316a5

Keep the branch tip separate from the merge commit so semmle-code QLDoc checks compare against the merged CodeQL tree rather than the pre-merge first parent. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jketema reviewed Sep 2, 2026

View reviewed changes

Navigation Menu

Uh oh!

Kotlin: support 2.4.20-RC2 - #22404

Kotlin: support 2.4.20-RC2#22404
andersfugmann wants to merge 10 commits into
mainfrom
andersfugmann/kotlin-2.4.20rc

andersfugmann commented Aug 21, 2026 •

edited

Loading

Uh oh!

andersfugmann commented Aug 28, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

jketema left a comment

Uh oh!

jketema Sep 2, 2026

Uh oh!

jketema Sep 2, 2026

Uh oh!

jketema Sep 2, 2026

Uh oh!

jketema Sep 2, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

andersfugmann commented Aug 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Motivation for each change

Compatibility

Validation

Uh oh!

andersfugmann commented Aug 28, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Copilot review overview

Uh oh!

jketema left a comment

Choose a reason for hiding this comment

Uh oh!

jketema Sep 2, 2026

Choose a reason for hiding this comment

Uh oh!

jketema Sep 2, 2026

Choose a reason for hiding this comment

Uh oh!

jketema Sep 2, 2026

Choose a reason for hiding this comment

Uh oh!

jketema Sep 2, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

andersfugmann commented Aug 21, 2026 •

edited

Loading