JVM: add inline lambdas' captured parameters to constructor first

This makes the code a bit cleaner, but has no effect other than that.

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/AnonymousObjectTransformer.kt

@@ -511,30 +511,20 @@ class AnonymousObjectTransformer(
             val capturedOuterThisTypes = mutableSetOf<String>()
             for (info in capturedLambdas) {
                 for (desc in info.capturedVars) {
-                    // Merge all outer `this` of the same type captured by inlined lambdas, since they have to be the same
-                    // object. Outer `this` captured by the original object itself should have been renamed above,
-                    // and can have a different value even if the same type is captured by a lambda.
-                    val recapturedParamInfo = if (isThis0(desc.fieldName))
-                        capturedParamBuilder.addCapturedParam(desc, desc.fieldName, !capturedOuterThisTypes.add(desc.type.className))
-                    else
-                        capturedParamBuilder.addCapturedParam(desc, addUniqueField(desc.fieldName + INLINE_TRANSFORMATION_SUFFIX), false)
+                    val recapturedParamInfo = constructorParamBuilder.addCapturedParam(
+                        desc,
+                        // Merge all outer `this` of the same type captured by inlined lambdas, since they have to be the same
+                        // object. Outer `this` captured by the original object itself should have been renamed above,
+                        // and can have a different value even if the same type is captured by a lambda.
+                        if (isThis0(desc.fieldName)) desc.fieldName else addUniqueField(desc.fieldName + INLINE_TRANSFORMATION_SUFFIX),
+                        (isThis0(desc.fieldName) && !capturedOuterThisTypes.add(desc.type.className))
+                    )
                     if (desc.isSuspend) {
                         recapturedParamInfo.functionalArgument = NonInlineArgumentForInlineSuspendParameter.INLINE_LAMBDA_AS_VARIABLE
                     }
-                    val composed = StackValue.field(
-                        desc.type,
-                        oldObjectType, /*TODO owner type*/
-                        recapturedParamInfo.newFieldName,
-                        false,
-                        StackValue.LOCAL_0
-                    )
-                    recapturedParamInfo.remapValue = composed
+                    capturedParamBuilder.addCapturedParam(recapturedParamInfo, recapturedParamInfo.newFieldName).remapValue =
+                        StackValue.field(desc.type, oldObjectType, recapturedParamInfo.newFieldName, false, StackValue.LOCAL_0)
                     allRecapturedParameters.add(desc)
-
-                    // DO NOT assign a remap value to the constructor parameter - this would cause the inliner to miscount
-                    // the arguments, eventually generating code that overwrites some of these captures with other stuff.
-                    // Plus we don't really want to remap local loads to field reads anyway, the latter are faster.
-                    constructorParamBuilder.addCapturedParam(recapturedParamInfo, recapturedParamInfo.newFieldName).remapValue = null
                 }
             }
         } else if (capturedLambdas.isNotEmpty()) {
@@ -545,12 +535,10 @@ class AnonymousObjectTransformer(
                 ?: throw AssertionError("Expecting RegeneratedLambdaFieldRemapper, but ${parentFieldRemapper.parent}")
             val ownerType = Type.getObjectType(parent.originalLambdaInternalName)
             val desc = CapturedParamDesc(ownerType, AsmUtil.THIS, ownerType)
-            val recapturedParamInfo = capturedParamBuilder.addCapturedParam(desc, AsmUtil.CAPTURED_THIS_FIELD/*outer lambda/object*/, false)
-            val composed = StackValue.LOCAL_0
-            recapturedParamInfo.remapValue = composed
+            val recapturedParamInfo =
+                constructorParamBuilder.addCapturedParam(desc, AsmUtil.CAPTURED_THIS_FIELD/*outer lambda/object*/, false)
+            capturedParamBuilder.addCapturedParam(recapturedParamInfo, recapturedParamInfo.newFieldName).remapValue = StackValue.LOCAL_0
             allRecapturedParameters.add(desc)
-
-            constructorParamBuilder.addCapturedParam(recapturedParamInfo, recapturedParamInfo.newFieldName).remapValue = null
         }
 
         transformationInfo.allRecapturedParameters = allRecapturedParameters

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LocalDeclarationsLowering.kt

@@ -172,13 +172,9 @@ class LocalDeclarationsLowering(
         val capturedValueToField: MutableMap<IrValueDeclaration, PotentiallyUnusedField> = mutableMapOf()
 
         override fun irGet(startOffset: Int, endOffset: Int, valueDeclaration: IrValueDeclaration): IrExpression? {
-            // On the JVM backend, `AnonymousObjectTransformer` in the bytecode inliner uses field assignment
-            // instructions to find captured parameters. Most of the time this is unimportant, as captured
-            // parameters are effectively indistinguishable from normal ones; the exception is ones that can
-            // take an inline lambda value, as the parameter needs to be replaced with the lambda's capture.
-            // Thus we cannot erase the field - the inliner won't handle the inline lambda without it.
-            // (Most of the time this is inconsequential - if the object really is instantiated with an inline
-            // lambda, the field will be erased completely regardless of whether it's used.)
+            // TODO: this used to be a hack for the JVM bytecode inliner (which misbehaved when inline lambdas had no fields),
+            //  but it's no longer necessary. It is only here for backwards compatibility with old kotlinc versions
+            //  and can be removed, probably in 1.9.
             if (!forceFieldsForInlineCaptures || !valueDeclaration.isInlineDeclaration()) {
                 // We're in the initializer scope, which will be moved to a primary constructor later.
                 // Thus we can directly use that constructor's context and read from a parameter instead of a field.