[K/N][IR] Fix for https://youtrack.jetbrains.com/issue/KT-48559

Aligned SAM conversion lowering with the JVM's one
Also refactored other places with erasure

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/descriptors/DescriptorUtils.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.backend.konan.ir.getSuperClassNotAny
 import org.jetbrains.kotlin.backend.konan.ir.getSuperInterfaces
 import org.jetbrains.kotlin.backend.konan.llvm.isVoidAsReturnType
 import org.jetbrains.kotlin.backend.konan.llvm.longName
+import org.jetbrains.kotlin.backend.konan.lower.erasedUpperBound
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
 import org.jetbrains.kotlin.ir.IrBuiltIns
@@ -19,7 +20,6 @@ import org.jetbrains.kotlin.ir.expressions.IrConst
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.types.IrType
-import org.jetbrains.kotlin.ir.types.classifierOrFail
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.resolve.annotations.argumentValue
 import org.jetbrains.kotlin.resolve.constants.StringValue
@@ -150,21 +150,14 @@ private fun IrFunction.bridgeDirectionToAt(overriddenFunction: IrFunction, index
     return if (otherKind == kind)
         BridgeDirection.NONE
     else when (kind) {
-        TypeKind.VOID, TypeKind.REFERENCE -> BridgeDirection(irClass?.erasure(), BridgeDirectionKind.UNBOX)
+        TypeKind.VOID, TypeKind.REFERENCE -> BridgeDirection(irClass?.erasedUpperBound, BridgeDirectionKind.UNBOX)
         TypeKind.VALUE_TYPE -> BridgeDirection(
-                irClass?.erasure().takeIf { otherKind == TypeKind.VOID } /* Otherwise erase to [Any?] */,
+                irClass?.erasedUpperBound.takeIf { otherKind == TypeKind.VOID } /* Otherwise erase to [Any?] */,
                 BridgeDirectionKind.BOX)
         TypeKind.ABSENT -> error("TypeKind.ABSENT should be on both sides")
     }
 }
 
-private tailrec fun IrType.erasure(): IrClass =
-        when (val classifier = classifierOrFail) {
-            is IrClassSymbol -> classifier.owner
-            is IrTypeParameterSymbol -> classifier.owner.superTypes.first().erasure()
-            else -> error(classifier)
-        }
-
 internal class BridgeDirections(private val array: Array<BridgeDirection>) {
     constructor(irFunction: IrSimpleFunction, overriddenFunction: IrSimpleFunction)
             : this(Array<BridgeDirection>(ParameterIndex.allParametersCount(irFunction)) {

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/IrToBitcode.kt

@@ -1519,7 +1519,8 @@ internal class CodeGeneratorVisitor(val context: Context, val lifetimes: Map<IrE
 
     private fun evaluateCast(value: IrTypeOperatorCall): LLVMValueRef {
         context.log{"evaluateCast                   : ${ir2string(value)}"}
-        val dstClass = value.typeOperand.getClass()!!
+        val dstClass = value.typeOperand.getClass()
+                ?: error("No class for ${value.typeOperand.render()} from \n${functionGenerationContext.irFunction?.render()}")
 
         val srcArg = evaluateExpression(value.argument)
         assert(srcArg.type == codegen.kObjHeaderPtr)

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/BridgesBuilding.kt

@@ -211,7 +211,7 @@ private fun IrBlockBodyBuilder.buildTypeSafeBarrier(function: IrFunction,
         if (!typeSafeBarrierDescription.checkParameter(i))
             continue
 
-        val type = originalValueParameters[i].type.erasureForTypeOperation()
+        val type = originalValueParameters[i].type.erasure()
         // Note: erasing to single type is not entirely correct if type parameter has multiple upper bounds.
         // In this case the compiler could generate multiple type checks, one for each upper bound.
         // But let's keep it simple here for now; JVM backend doesn't do this anyway.
@@ -264,4 +264,4 @@ private fun Context.buildBridge(startOffset: Int, endOffset: Int,
         +irReturn(delegatingCall)
     }
     return bridge
-}
+}

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/FunctionReferenceLowering.kt

@@ -111,7 +111,7 @@ internal class FunctionReferenceLowering(val context: Context): FileLoweringPass
                         return super.visitTypeOperator(expression)
                     }
                     reference.transformChildrenVoid()
-                    return transformFunctionReference(reference, expression.typeOperand)
+                    return transformFunctionReference(reference, expression.typeOperand.erasure())
                 }
                 return super.visitTypeOperator(expression)
             }
@@ -377,8 +377,7 @@ internal class FunctionReferenceLowering(val context: Context): FileLoweringPass
                 val adaptedParameter = adaptedParameters[index]
                 if (originalParameter.defaultValue != null) return false
                 if (originalParameter.isVararg) {
-                    if (originalParameter.varargElementType!!.erasureForTypeOperation()
-                            == adaptedParameter.type.erasureForTypeOperation())
+                    if (originalParameter.varargElementType!!.erasure() == adaptedParameter.type.erasure())
                         return true
                 }
                 ++index

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TypeOperatorLowering.kt

@@ -17,42 +17,44 @@ import org.jetbrains.kotlin.ir.expressions.IrTypeOperator
 import org.jetbrains.kotlin.ir.expressions.IrTypeOperatorCall
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
-import org.jetbrains.kotlin.ir.types.IrSimpleType
-import org.jetbrains.kotlin.ir.types.IrType
-import org.jetbrains.kotlin.ir.types.makeNotNull
-import org.jetbrains.kotlin.ir.types.makeNullable
+import org.jetbrains.kotlin.ir.types.*
+import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.util.irCall
-import org.jetbrains.kotlin.ir.util.isSimpleTypeWithQuestionMark
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
-internal fun IrType.erasureForTypeOperation(): IrType {
+// TODO: Similar to IrType.erasedUpperBound from jvm.ir
+internal fun IrType.erasure(): IrType {
     if (this !is IrSimpleType) return this
 
-    return when (val classifier = classifier) {
-        is IrClassSymbol -> this
+    val upperBound = when (val classifier = classifier) {
+        is IrClassSymbol -> classifier.defaultType
         is IrTypeParameterSymbol -> {
-            val upperBound = classifier.owner.superTypes.firstOrNull()
-                    ?: TODO("${classifier.descriptor} : ${classifier.descriptor.upperBounds}")
-
-            if (this.hasQuestionMark) {
-                // `T?`
-                upperBound.erasureForTypeOperation().makeNullable()
-            } else {
-                upperBound.erasureForTypeOperation()
-            }
+            // Pick the (necessarily unique) non-interface upper bound if it exists
+            classifier.owner.superTypes.firstOrNull {
+                it.classOrNull?.owner?.isInterface == false
+            } ?:
+            // Otherwise, choose either the first IrClass supertype or recurse.
+            // In the first case, all supertypes are interface types and the choice was arbitrary.
+            // In the second case, there is only a single supertype.
+            classifier.owner.superTypes.first().erasure()
         }
         else -> TODO(classifier.toString())
     }
+
+    return if (this.hasQuestionMark)
+        upperBound.makeNullable()
+    else
+        upperBound
 }
 
+internal val IrType.erasedUpperBound get() = this.erasure().getClass() ?: error(this.render())
+
 internal class TypeOperatorLowering(val context: CommonBackendContext) : FileLoweringPass, IrBuildingTransformer(context) {
 
     override fun lower(irFile: IrFile) {
         irFile.transformChildren(this, null)
     }
 
-    private fun IrType.erasure(): IrType = this.erasureForTypeOperation()
-
     private fun lowerCast(expression: IrTypeOperatorCall): IrExpression {
         builder.at(expression)
         val typeOperand = expression.typeOperand.erasure()

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/DFGBuilder.kt

@@ -5,18 +5,21 @@
 
 package org.jetbrains.kotlin.backend.konan.optimizations
 
-import org.jetbrains.kotlin.backend.common.atMostOne
 import org.jetbrains.kotlin.backend.common.ir.allParameters
 import org.jetbrains.kotlin.backend.common.ir.ir2stringWhole
 import org.jetbrains.kotlin.backend.common.ir.simpleFunctions
 import org.jetbrains.kotlin.backend.common.peek
 import org.jetbrains.kotlin.backend.common.pop
 import org.jetbrains.kotlin.backend.common.push
-import org.jetbrains.kotlin.backend.konan.*
-import org.jetbrains.kotlin.backend.konan.descriptors.allOverriddenFunctions
-import org.jetbrains.kotlin.backend.konan.ir.*
-import org.jetbrains.kotlin.backend.konan.llvm.computeFunctionName
-import org.jetbrains.kotlin.backend.konan.llvm.localHash
+import org.jetbrains.kotlin.backend.konan.Context
+import org.jetbrains.kotlin.backend.konan.getInlinedClassNative
+import org.jetbrains.kotlin.backend.konan.ir.actualCallee
+import org.jetbrains.kotlin.backend.konan.ir.isAny
+import org.jetbrains.kotlin.backend.konan.ir.isObjCObjectType
+import org.jetbrains.kotlin.backend.konan.ir.isVirtualCall
+import org.jetbrains.kotlin.backend.konan.isNonGeneratedAnnotation
+import org.jetbrains.kotlin.backend.konan.logMultiple
+import org.jetbrains.kotlin.backend.konan.lower.erasedUpperBound
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.*
@@ -28,9 +31,6 @@ import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
-import org.jetbrains.kotlin.ir.util.constructors
-import org.jetbrains.kotlin.ir.util.getArguments
-import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
@@ -566,27 +566,6 @@ internal class ModuleDFGBuilder(val context: Context, val irModule: IrModuleFrag
             )
         }
 
-        private fun IrType.erasure(): IrType {
-            if (this !is IrSimpleType) return this
-
-            val classifier = this.classifier
-            return when (classifier) {
-                is IrClassSymbol -> this
-                is IrTypeParameterSymbol -> {
-                    val upperBound = classifier.owner.superTypes.singleOrNull() ?:
-                    TODO("${classifier.descriptor} : ${classifier.descriptor.upperBounds}")
-
-                    if (this.hasQuestionMark) {
-                        // `T?`
-                        upperBound.erasure().makeNullable()
-                    } else {
-                        upperBound.erasure()
-                    }
-                }
-                else -> TODO(classifier.toString())
-            }
-        }
-
         private fun expressionToEdge(expression: IrExpression) = expressionToScopedEdge(expression).value
 
         private fun expressionToScopedEdge(expression: IrExpression) =
@@ -595,7 +574,7 @@ internal class ModuleDFGBuilder(val context: Context, val irModule: IrModuleFrag
                         Scoped(
                                 DataFlowIR.Edge(
                                         it.value,
-                                        symbolTable.mapClassReferenceType(expression.typeOperand.erasure().getClass()!!)
+                                        symbolTable.mapClassReferenceType(expression.typeOperand.erasedUpperBound)
                                 ), it.scope)
                     }
                 else {