IR: refactor resolveFakeOverride call sites

Split it to 4 functions for clarity: resolveFakeOverride,
resolveFakeOverrideOrFail, resolveFakeOverrideMaybeAbstract,
resolveFakeOverrideMaybeAbstractOrFail. Remove/inline duplicated
utilities and remove unused parameters.

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/export/ExportModelGenerator.kt

@@ -778,7 +778,7 @@ private fun shouldDeclarationBeExported(declaration: IrDeclarationWithName, cont
 
 fun IrOverridableDeclaration<*>.isAllowedFakeOverriddenDeclaration(context: JsIrBackendContext): Boolean {
     val firstExportedRealOverride = runIf(isFakeOverride) {
-        resolveFakeOverrideOrNull(allowAbstract = true) { it === this || it.parentClassOrNull?.isExported(context) != true }
+        resolveFakeOverrideMaybeAbstract { it === this || it.parentClassOrNull?.isExported(context) != true }
     }
 
     if (firstExportedRealOverride?.parentClassOrNull.isExportedInterface(context)) {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/ic/IdSignatureHashCalculator.kt

@@ -6,14 +6,16 @@
 package org.jetbrains.kotlin.ir.backend.js.ic
 
 import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrFile
+import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrFunctionReference
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.util.IdSignature
 import org.jetbrains.kotlin.ir.util.isFakeOverride
-import org.jetbrains.kotlin.ir.util.render
-import org.jetbrains.kotlin.ir.util.resolveFakeOverride
+import org.jetbrains.kotlin.ir.util.resolveFakeOverrideOrFail
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
@@ -35,12 +37,8 @@ internal class IdSignatureHashCalculator(private val icHasher: ICHasher) {
 
     private val IrFunction.inlineFunctionFlatHash: ICHash
         get() = inlineFunctionFlatHashes.getOrPut(this) {
-            val flatHash = if (isFakeOverride && this is IrSimpleFunction) {
-                resolveFakeOverride()?.let { icHasher.calculateIrFunctionHash(it) }
-                    ?: icError("can not resolve fake override for ${render()}")
-            } else {
-                icHasher.calculateIrFunctionHash(this)
-            }
+            val function = if (isFakeOverride && this is IrSimpleFunction) resolveFakeOverrideOrFail() else this
+            val flatHash = icHasher.calculateIrFunctionHash(function)
             ICHash(symbol.calculateSymbolHash().hash.combineWith(flatHash.hash))
         }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BridgesConstruction.kt

@@ -248,3 +248,9 @@ data class IrBasedFunctionHandle(val function: IrSimpleFunction) : FunctionHandl
     override fun getOverridden() =
         function.overriddenSymbols.map { IrBasedFunctionHandle(it.owner) }
 }
+
+private fun IrSimpleFunction.findInterfaceImplementation(): IrSimpleFunction? {
+    if (isReal) return null
+
+    return resolveFakeOverride()?.run { if (parentAsClass.isInterface) this else null }
+}

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

@@ -195,7 +195,7 @@ fun translateCall(
 
     expression.superQualifierSymbol?.let { superQualifier ->
         val (target: IrSimpleFunction, klass: IrClass) = if (superQualifier.owner.isInterface) {
-            val impl = function.resolveFakeOverride()!!
+            val impl = function.resolveFakeOverrideOrFail()
             Pair(impl, impl.parentAsClass)
         } else {
             Pair(function, superQualifier.owner)