JVM: rename this$0 when regenerating nested objects too

In the old backend, this was unnecessary because nested objects would
reference their lambdas' captures through the original this$0. On
JVM_IR, using loose capture fields means a name/descriptor clash can
occur on any level of nesting, not just the top.

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

@@ -462,6 +462,29 @@ class AnonymousObjectTransformer(
         val indexToFunctionalArgument = transformationInfo.functionalArguments
         val capturedParams = HashSet<Int>()
 
+        // Possible cases where we need to add each lambda's captures separately:
+        //
+        //   1. Top-level object in an inline lambda that is *not* being inlined into another object. In this case, we
+        //      have no choice but to add a separate field for each captured variable. `capturedLambdas` is either empty
+        //      (already have the fields) or contains the parent lambda object (captures used to be read from it, but
+        //      the object will be removed and its contents inlined).
+        //
+        //   2. Top-level object in a named inline function. Again, there's no option but to add separate fields.
+        //      `capturedLambdas` contains all lambdas used by this object and nested objects.
+        //
+        //   3. Nested object, either in an inline lambda or an inline function. This case has two subcases:
+        //      * The object's captures are passed as separate arguments (e.g. KT-28064 style object that used to be in a lambda);
+        //        we *could* group them into `this$0` now, but choose not to. Lambdas are replaced by their captures to match.
+        //      * The object's captures are already grouped into `this$0`; this includes captured lambda parameters (for objects in
+        //        inline functions) and a reference to the outer object or lambda (for objects in lambdas), so `capturedLambdas` is
+        //        empty anyway.
+        //
+        // The only remaining case is a top-level object inside a (crossinline) lambda that is inlined into another object.
+        // Then, the reference to the soon-to-be-removed lambda class containing the captures (and it exists, or else the object
+        // would not have needed regeneration in the first place) is simply replaced with a reference to the outer object, and
+        // that object will contain loose fields for everything we need to capture.
+        val topLevelInCrossinlineLambda = parentFieldRemapper is InlinedLambdaRemapper && !parentFieldRemapper.parent!!.isRoot
+
         //load captured parameters and patch instruction list
         //  NB: there is also could be object fields
         val toDelete = arrayListOf<AbstractInsnNode>()
@@ -470,10 +493,12 @@ class AnonymousObjectTransformer(
             val parameterAload = fieldNode.previous as VarInsnNode
             val varIndex = parameterAload.`var`
             val functionalArgument = indexToFunctionalArgument[varIndex]
-            val newFieldName = if (isThis0(fieldName) && shouldRenameThis0(parentFieldRemapper, indexToFunctionalArgument.values))
-                getNewFieldName(fieldName, true)
-            else
-                fieldName
+            // If an outer `this` is already captured by this object, rename it if any inline lambda will capture
+            // one of the same type, causing the code below to create a clash. Note that the values can be different.
+            // TODO: this is only really necessary if there will be a name *and* type clash.
+            val shouldRename = !topLevelInCrossinlineLambda && isThis0(fieldName) &&
+                    indexToFunctionalArgument.values.any { it is LambdaInfo && it.capturedVars.any { it.fieldName == fieldName } }
+            val newFieldName = if (shouldRename) addUniqueField(fieldName + INLINE_FUN_THIS_0_SUFFIX) else fieldName
             val info = capturedParamBuilder.addCapturedParam(
                 Type.getObjectType(transformationInfo.oldClassName), fieldName, newFieldName,
                 Type.getType(fieldNode.desc), functionalArgument is LambdaInfo, null
@@ -508,35 +533,17 @@ class AnonymousObjectTransformer(
         //For all inlined lambdas add their captured parameters
         //TODO: some of such parameters could be skipped - we should perform additional analysis
         val allRecapturedParameters = ArrayList<CapturedParamDesc>()
-        if (parentFieldRemapper !is InlinedLambdaRemapper || parentFieldRemapper.parent!!.isRoot) {
-            // Possible cases:
-            //
-            //   1. Top-level object in an inline lambda that is *not* being inlined into another object. In this case, we
-            //      have no choice but to add a separate field for each captured variable. `capturedLambdas` is either empty
-            //      (already have the fields) or contains the parent lambda object (captures used to be read from it, but
-            //      the object will be removed and its contents inlined).
-            //
-            //   2. Top-level object in a named inline function. Again, there's no option but to add separate fields.
-            //      `capturedLambdas` contains all lambdas used by this object and nested objects.
-            //
-            //   3. Nested object, either in an inline lambda or an inline function. This case has two subcases:
-            //      * The object's captures are passed as separate arguments (e.g. KT-28064 style object that used to be in a lambda);
-            //        we could group them into `this$0` now, but choose not to. Lambdas are replaced by their captures.
-            //      * The object's captures are already grouped into `this$0`; this includes captured lambda parameters (for objects in
-            //        inline functions) and a reference to the outer object or lambda (for objects in lambdas), so `capturedLambdas` is
-            //        empty and the choice doesn't matter.
-            //
-            val alreadyAdded = HashMap<String, CapturedParamInfo>()
+        if (!topLevelInCrossinlineLambda) {
+            val capturedOuterThisTypes = mutableSetOf<String>()
             for (info in capturedLambdas) {
                 for (desc in info.capturedVars) {
-                    val key = desc.fieldName + "$$$" + desc.type.className
-                    val alreadyAddedParam = alreadyAdded[key]
-
-                    val recapturedParamInfo = capturedParamBuilder.addCapturedParam(
-                        desc,
-                        alreadyAddedParam?.newFieldName ?: getNewFieldName(desc.fieldName, false),
-                        alreadyAddedParam != null
-                    )
+                    // 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)
                     if (info is ExpressionLambda && info.isCapturedSuspend(desc)) {
                         recapturedParamInfo.functionalArgument = NonInlineableArgumentForInlineableParameterCalledInSuspend
                     }
@@ -551,10 +558,6 @@ class AnonymousObjectTransformer(
                     allRecapturedParameters.add(desc)
 
                     constructorParamBuilder.addCapturedParam(recapturedParamInfo, recapturedParamInfo.newFieldName).remapValue = composed
-
-                    if (isThis0(desc.fieldName)) {
-                        alreadyAdded.put(key, recapturedParamInfo)
-                    }
                 }
             }
         } else if (capturedLambdas.isNotEmpty()) {
@@ -579,24 +582,6 @@ class AnonymousObjectTransformer(
         return constructorAdditionalFakeParams
     }
 
-    private fun shouldRenameThis0(parentFieldRemapper: FieldRemapper, values: Collection<FunctionalArgument>): Boolean {
-        return if (isFirstDeclSiteLambdaFieldRemapper(parentFieldRemapper)) {
-            values.any { it is LambdaInfo && it.capturedVars.any { isThis0(it.fieldName) } }
-        } else false
-    }
-
-    private fun getNewFieldName(oldName: String, originalField: Boolean): String {
-        if (AsmUtil.CAPTURED_THIS_FIELD == oldName) {
-            return if (!originalField) {
-                oldName
-            } else {
-                //rename original 'this$0' in declaration site lambda (inside inline function) to use this$0 only for outer lambda/object access on call site
-                addUniqueField(oldName + INLINE_FUN_THIS_0_SUFFIX)
-            }
-        }
-        return addUniqueField(oldName + INLINE_TRANSFORMATION_SUFFIX)
-    }
-
     private fun addUniqueField(name: String): String {
         val existNames = fieldNames.getOrPut(name) { LinkedList() }
         val suffix = if (existNames.isEmpty()) "" else "$" + existNames.size
@@ -604,7 +589,4 @@ class AnonymousObjectTransformer(
         existNames.add(newName)
         return newName
     }
-
-    private fun isFirstDeclSiteLambdaFieldRemapper(parentRemapper: FieldRemapper): Boolean =
-        parentRemapper !is RegeneratedLambdaFieldRemapper && parentRemapper !is InlinedLambdaRemapper
 }

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxInlineCodegenTestGenerated.java

@@ -647,6 +647,18 @@ public class FirBlackBoxInlineCodegenTestGenerated extends AbstractFirBlackBoxIn
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt

@@ -0,0 +1,14 @@
+// FILE: 1.kt
+package test
+
+class C(val x: String) {
+    fun f(y: String) = C(y).g { x }
+
+    inline fun g(crossinline h: () -> String) =
+        { { h() + x }() }()
+}
+
+// FILE: 2.kt
+import test.*
+
+fun box() = C("O").f("K")

compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt

@@ -0,0 +1,14 @@
+// FILE: 1.kt
+package test
+
+class C(val x: String) {
+    inline fun f(crossinline h: () -> String) = C("").g { x + h() }
+
+    inline fun g(crossinline h: () -> String) =
+        { { h() + x }() }()
+}
+
+// FILE: 2.kt
+import test.*
+
+fun box() = C("O").f { "K" }

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxInlineCodegenTestGenerated.java

@@ -647,6 +647,18 @@ public class BlackBoxInlineCodegenTestGenerated extends AbstractBlackBoxInlineCo
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/CompileKotlinAgainstInlineKotlinTestGenerated.java

@@ -647,6 +647,18 @@ public class CompileKotlinAgainstInlineKotlinTestGenerated extends AbstractCompi
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxInlineCodegenTestGenerated.java

@@ -647,6 +647,18 @@ public class IrBlackBoxInlineCodegenTestGenerated extends AbstractIrBlackBoxInli
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrCompileKotlinAgainstInlineKotlinTestGenerated.java

@@ -647,6 +647,18 @@ public class IrCompileKotlinAgainstInlineKotlinTestGenerated extends AbstractIrC
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/JvmIrAgainstOldBoxInlineTestGenerated.java

@@ -647,6 +647,18 @@ public class JvmIrAgainstOldBoxInlineTestGenerated extends AbstractJvmIrAgainstO
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/JvmOldAgainstIrBoxInlineTestGenerated.java

@@ -647,6 +647,18 @@ public class JvmOldAgainstIrBoxInlineTestGenerated extends AbstractJvmOldAgainst
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @Test
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @Test
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @Test
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenInlineES6TestGenerated.java

@@ -506,6 +506,16 @@ public class IrJsCodegenInlineES6TestGenerated extends AbstractIrJsCodegenInline
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/twoDifferentDispatchReceivers.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenInlineTestGenerated.java

@@ -506,6 +506,16 @@ public class IrJsCodegenInlineTestGenerated extends AbstractIrJsCodegenInlineTes
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/twoDifferentDispatchReceivers.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenInlineTestGenerated.java

@@ -506,6 +506,16 @@ public class JsCodegenInlineTestGenerated extends AbstractJsCodegenInlineTest {
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_3.kt");
             }
 
+            @TestMetadata("kt8668_nested.kt")
+            public void testKt8668_nested() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested.kt");
+            }
+
+            @TestMetadata("kt8668_nested_2.kt")
+            public void testKt8668_nested_2() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/kt8668_nested_2.kt");
+            }
+
             @TestMetadata("twoDifferentDispatchReceivers.kt")
             public void testTwoDifferentDispatchReceivers() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/anonymousObject/twoCapturedReceivers/twoDifferentDispatchReceivers.kt");