Removed useless as casts from compiler code

It allows compiling code with K2 and enabled `-Werror`

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

@@ -120,9 +120,7 @@ class FlattenStringConcatenationLowering(val context: CommonBackendContext) : Fi
                 if (superQualifierSymbol != null)
                     return false
 
-                val function = symbol.owner as? IrSimpleFunction
-                    ?: return false
-
+                val function = symbol.owner
                 return function.isToString || function.isNullableToString
             }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/jsAstUtils.kt

@@ -137,7 +137,7 @@ fun translateFunction(declaration: IrFunction, name: JsName?, context: JsGenerat
 
 private fun isFunctionTypeInvoke(receiver: JsExpression?, call: IrCall): Boolean {
     if (receiver == null || receiver is JsThisRef) return false
-    val simpleFunction = call.symbol.owner as? IrSimpleFunction ?: return false
+    val simpleFunction = call.symbol.owner
     val receiverType = simpleFunction.dispatchReceiverParameter?.type ?: return false
 
     if (call.origin === JsStatementOrigins.EXPLICIT_INVOKE) return false

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/EnumExternalEntriesLowering.kt

@@ -22,7 +22,6 @@ import org.jetbrains.kotlin.ir.builders.irExprBody
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetFieldImpl
@@ -101,8 +100,8 @@ class EnumExternalEntriesLowering(private val context: JvmBackendContext) : File
     }
 
     override fun visitCall(expression: IrCall): IrExpression {
-        val owner = expression.symbol.owner as? IrSimpleFunction
-        val parentClass = owner?.parent as? IrClass ?: return super.visitCall(expression)
+        val owner = expression.symbol.owner
+        val parentClass = owner.parent as? IrClass ?: return super.visitCall(expression)
         val shouldBeLowered = owner.name == SpecialNames.ENUM_GET_ENTRIES && parentClass.isEnumClassWhichRequiresExternalEntries()
         if (!shouldBeLowered) return super.visitCall(expression)
         val field = state!!.getEntriesFieldForEnum(parentClass)

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmOptimizationLowering.kt

@@ -114,7 +114,7 @@ class JvmOptimizationLowering(val context: JvmBackendContext) : FileLoweringPass
         }
 
         private fun optimizePropertyAccess(expression: IrCall, data: IrDeclaration?): IrExpression {
-            val accessor = expression.symbol.owner as? IrSimpleFunction ?: return expression
+            val accessor = expression.symbol.owner
             if (accessor.modality != Modality.FINAL || accessor.isExternal) return expression
             val property = accessor.correspondingPropertySymbol?.owner ?: return expression
             if (property.isLateinit) return expression
@@ -357,9 +357,8 @@ class JvmOptimizationLowering(val context: JvmBackendContext) : FileLoweringPass
             when (statement) {
                 is IrDoWhileLoop -> {
                     // Expecting counter loop
-                    val doWhileLoop = statement as? IrDoWhileLoop ?: return null
-                    if (doWhileLoop.origin != JvmLoweredStatementOrigin.DO_WHILE_COUNTER_LOOP) return null
-                    val doWhileLoopBody = doWhileLoop.body as? IrComposite ?: return null
+                    if (statement.origin != JvmLoweredStatementOrigin.DO_WHILE_COUNTER_LOOP) return null
+                    val doWhileLoopBody = statement.body as? IrComposite ?: return null
                     if (doWhileLoopBody.origin != IrStatementOrigin.FOR_LOOP_INNER_WHILE) return null
                     val iterationInitialization = doWhileLoopBody.statements[0] as? IrComposite ?: return null
                     val loopVariableIndex = iterationInitialization.statements.indexOfFirst { it.isLoopVariable() }

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmPropertiesLowering.kt

@@ -51,7 +51,7 @@ class JvmPropertiesLowering(private val backendContext: JvmBackendContext) : IrE
     }
 
     override fun visitCall(expression: IrCall): IrExpression {
-        val simpleFunction = (expression.symbol.owner as? IrSimpleFunction) ?: return super.visitCall(expression)
+        val simpleFunction = expression.symbol.owner
         val property = simpleFunction.correspondingPropertySymbol?.owner ?: return super.visitCall(expression)
         expression.transformChildrenVoid()
 

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/ResolveInlineCalls.kt

@@ -39,7 +39,7 @@ class ResolveInlineCalls(val context: JvmBackendContext) : IrElementVisitorVoid,
         expression.acceptChildren(this, null)
 
         if (!expression.symbol.owner.isInlineFunctionCall(context)) return
-        val maybeFakeOverrideOfMultiFileBridge = expression.symbol.owner as? IrSimpleFunction ?: return
+        val maybeFakeOverrideOfMultiFileBridge = expression.symbol.owner
         val resolved =
             maybeFakeOverrideOfMultiFileBridge.resolveMultiFileFacadeMember() ?: maybeFakeOverrideOfMultiFileBridge.resolveFakeOverride()
             ?: return

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/GenericReturnTypeLowering.kt

@@ -8,20 +8,17 @@ package org.jetbrains.kotlin.backend.wasm.lower
 import org.jetbrains.kotlin.backend.common.FileLoweringPass
 import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
-import org.jetbrains.kotlin.backend.common.lower.irComposite
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.ir.backend.js.utils.erasedUpperBound
 import org.jetbrains.kotlin.ir.backend.js.utils.realOverrideTarget
 import org.jetbrains.kotlin.ir.builders.irImplicitCast
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.defaultType
 import org.jetbrains.kotlin.ir.util.irCall
-import org.jetbrains.kotlin.ir.util.isTypeParameter
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
 /**
@@ -48,8 +45,7 @@ class GenericReturnTypeLowering(val context: WasmBackendContext) : FileLoweringP
     }
 
     private fun transformGenericCall(call: IrCall, scopeOwnerSymbol: IrSymbol): IrExpression {
-        val function: IrSimpleFunction =
-            call.symbol.owner as? IrSimpleFunction ?: return call
+        val function = call.symbol.owner
 
         val erasedReturnType: IrType =
             function.realOverrideTarget.returnType.eraseUpperBoundType()

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/preprocessor/IrInterpreterConstGetterPreprocessor.kt

@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFunction
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetObjectValueImpl
@@ -25,8 +24,7 @@ class IrInterpreterConstGetterPreprocessor : IrInterpreterPreprocessor {
     }
 
     override fun visitCall(expression: IrCall, data: IrInterpreterPreprocessorData): IrElement {
-        val function = (expression.symbol.owner as? IrSimpleFunction) ?: return super.visitCall(expression, data)
-        val field = function.correspondingPropertySymbol?.owner?.backingField ?: return super.visitCall(expression, data)
+        val field = expression.symbol.owner.correspondingPropertySymbol?.owner?.backingField ?: return super.visitCall(expression, data)
         return expression.lowerConstRead(field, data) ?: super.visitCall(expression, data)
     }
 

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/transformer/IrConstOnlyNecessaryTransformer.kt

@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.interpreter.IrInterpreter
 import org.jetbrains.kotlin.ir.interpreter.checker.EvaluationMode
@@ -35,7 +34,7 @@ internal class IrConstOnlyNecessaryTransformer(
     interpreter, irFile, mode, checker, evaluatedConstTracker, inlineConstTracker, onWarning, onError, suppressExceptions
 ) {
     override fun visitCall(expression: IrCall, data: Data): IrElement {
-        val isConstGetter = (expression.symbol.owner as? IrSimpleFunction)?.correspondingPropertySymbol?.owner?.isConst == true
+        val isConstGetter = expression.symbol.owner.correspondingPropertySymbol?.owner?.isConst == true
         if (!data.inAnnotation && !isConstGetter) {
             expression.transformChildren(this, data)
             return expression

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrUtils.kt

@@ -17,9 +17,9 @@ import org.jetbrains.kotlin.ir.builders.irImplicitCast
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
-import org.jetbrains.kotlin.ir.overrides.IrUnimplementedOverridesStrategy
 import org.jetbrains.kotlin.ir.overrides.FakeOverrideBuilderStrategy
 import org.jetbrains.kotlin.ir.overrides.IrFakeOverrideBuilder
+import org.jetbrains.kotlin.ir.overrides.IrUnimplementedOverridesStrategy
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.symbols.impl.IrPropertySymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrSimpleFunctionSymbolImpl
@@ -28,11 +28,7 @@ import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
 import org.jetbrains.kotlin.ir.types.impl.makeTypeProjection
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
-import org.jetbrains.kotlin.name.ClassId
-import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.name.SpecialNames
-import org.jetbrains.kotlin.name.StandardClassIds
+import org.jetbrains.kotlin.name.*
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.*
 import java.io.StringWriter
@@ -842,7 +838,7 @@ fun IrClass.addSimpleDelegatingConstructor(
         )
     }
 
-val IrCall.isSuspend get() = (symbol.owner as? IrSimpleFunction)?.isSuspend == true
+val IrCall.isSuspend get() = symbol.owner.isSuspend
 val IrFunctionReference.isSuspend get() = (symbol.owner as? IrSimpleFunction)?.isSuspend == true
 
 val IrFunction.isOverridable get() = this is IrSimpleFunction && this.isOverridable