Kotlin 2.4.0: Address peer review

* Update documentation to only claim support for 2.4.0x
* Python test code; remove newlines between imports.
* Sync comments between kotlin 1.8 and 1.9
* Update code comments to attach where actually relevant,
  and improve comments on IrMemberAccessExpression<*>.extensionReceiverParameterIndex()

Author: andersfugmann

docs/codeql/reusables/supported-versions-compilers.rst

@@ -21,7 +21,7 @@
    Java,"Java 7 to 26 [6]_","javac (OpenJDK and Oracle JDK),
 
    Eclipse compiler for Java (ECJ) [7]_",``.java``
-   Kotlin,"Kotlin 1.8.0 to 2.4.\ *x*","kotlinc",``.kt``
+   Kotlin,"Kotlin 1.8.0 to 2.4.0\ *x*","kotlinc",``.kt``
    JavaScript,ECMAScript 2022 or lower,Not applicable,"``.js``, ``.jsx``, ``.mjs``, ``.es``, ``.es6``, ``.htm``, ``.html``, ``.xhtm``, ``.xhtml``, ``.vue``, ``.hbs``, ``.ejs``, ``.njk``, ``.json``, ``.yaml``, ``.yml``, ``.raml``, ``.xml`` [8]_"
    Python [9]_,"2.7, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13",Not applicable,``.py``
    Ruby [10]_,"up to 3.3",Not applicable,"``.rb``, ``.erb``, ``.gemspec``, ``Gemfile``"

java/kotlin-extractor/src/main/kotlin/utils/versions/v_1_8_0/Kotlin2ComponentRegistrar.kt

@@ -28,6 +28,8 @@ abstract class Kotlin2ComponentRegistrar : ComponentRegistrar {
 
     fun registerExtractorExtension(extension: IrGenerationExtension) {
         val p = project ?: throw IllegalStateException("registerExtractorExtension called before registerProjectComponents")
+        // Register with LoadingOrder.LAST to ensure the extractor runs after other
+        // IR generation plugins (like kotlinx.serialization) have generated their code.
         val extensionPoint = p.extensionArea.getExtensionPoint(IrGenerationExtension.extensionPointName)
         extensionPoint.registerExtension(extension, LoadingOrder.LAST, p)
     }

java/kotlin-extractor/src/main/kotlin/utils/versions/v_2_4_0/IrCompat.kt

@@ -30,33 +30,36 @@ val IrFunction.codeQlExtensionReceiverParameter: IrValueParameter?
     get() = parameters.firstOrNull { it.kind == org.jetbrains.kotlin.ir.declarations.IrParameterKind.ExtensionReceiver }
 
 // Helper: get the offset of value arguments in the arguments list
-// In 2.4.0, arguments[] includes dispatch/extension receivers before regular params
 private fun IrMemberAccessExpression<*>.valueArgumentOffset(): Int {
     val owner = symbol.owner as? IrFunction ?: return 0
     return owner.parameters.count { it.kind != org.jetbrains.kotlin.ir.declarations.IrParameterKind.Regular }
 }
 
 // IrMemberAccessExpression: valueArgumentsCount
+// In 2.4.0, arguments[] includes dispatch/extension receivers before regular params
 val IrMemberAccessExpression<*>.codeQlValueArgumentsCount: Int
     get() = arguments.size - valueArgumentOffset()
 
 // IrMemberAccessExpression: getValueArgument
+// In 2.4.0, arguments[] includes dispatch/extension receivers before regular params
 fun IrMemberAccessExpression<*>.codeQlGetValueArgument(index: Int): IrExpression? = arguments[index + valueArgumentOffset()]
 
 // IrMemberAccessExpression: putValueArgument
+// In 2.4.0, arguments[] includes dispatch/extension receivers before regular params
 fun IrMemberAccessExpression<*>.codeQlPutValueArgument(index: Int, value: IrExpression?) {
     arguments[index + valueArgumentOffset()] = value
 }
 
-// IrMemberAccessExpression: extensionReceiver
-// For IrCall/IrFunctionReference, look at symbol.owner (IrFunction) directly.
-// For IrPropertyReference, symbol.owner is IrProperty; use the getter's parameters instead.
+// Re-add accessor for the extensionReceiver property removed in Kotlin 2.4.0.
 val IrMemberAccessExpression<*>.codeQlExtensionReceiver: IrExpression?
     get() {
         val erp = extensionReceiverParameterIndex() ?: return null
         return arguments[erp]
     }
 
+// Find the argument index corresponding to the extension receiver parameter.
+// Calls and function references expose an IrFunction owner directly; property
+// references need to look through their getter or setter.
 private fun IrMemberAccessExpression<*>.extensionReceiverParameterIndex(): Int? {
     // Direct function owner (IrCall, IrFunctionReference, etc.)
     (symbol.owner as? IrFunction)?.codeQlExtensionReceiverParameter?.let {
@@ -118,4 +121,3 @@ fun codeQlAnnotationFromSymbolOwner(
 
 fun codeQlAnnotationFromSymbolOwner(type: IrType, symbol: IrConstructorSymbol): IrConstructorCall =
     IrAnnotationImpl.fromSymbolOwner(type, symbol)
-

java/ql/integration-tests/kotlin/all-platforms/enhanced-nullability/test.py

@@ -1,5 +1,4 @@
 import pathlib
-
 import pytest
 
 

java/ql/integration-tests/kotlin/all-platforms/external-property-overloads/test.py

@@ -1,5 +1,4 @@
 import commands
-
 import pytest
 
 

java/ql/integration-tests/kotlin/all-platforms/file_classes/test.py

@@ -1,5 +1,4 @@
 import commands
-
 import pytest
 
 

java/ql/integration-tests/kotlin/all-platforms/java-interface-redeclares-tostring/test.py

@@ -1,5 +1,4 @@
 import commands
-
 import pytest
 
 

java/ql/integration-tests/kotlin/all-platforms/kotlin_java_lowering_wildcards/test.py

@@ -1,5 +1,4 @@
 import commands
-
 import pytest