[IR] Add isHidden flag into IrValueParameter

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrValueParameterImpl.kt

@@ -38,7 +38,8 @@ class IrValueParameterImpl(
     override val type: IrType,
     override val varargElementType: IrType?,
     override val isCrossinline: Boolean,
-    override val isNoinline: Boolean
+    override val isNoinline: Boolean,
+    override val isHidden: Boolean = false
 ) : IrValueParameter() {
     @ObsoleteDescriptorBasedAPI
     override val descriptor: ParameterDescriptor

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrValueParameter.kt

@@ -40,7 +40,8 @@ internal class PersistentIrValueParameter(
     override val type: IrType,
     override val varargElementType: IrType?,
     override val isCrossinline: Boolean,
-    override val isNoinline: Boolean
+    override val isNoinline: Boolean,
+    override val isHidden: Boolean = false
 ) : IrValueParameter(),
     PersistentIrDeclarationBase<ValueParameterCarrier>,
     ValueParameterCarrier {
@@ -52,7 +53,7 @@ internal class PersistentIrValueParameter(
     init {
         symbol.bind(this)
     }
-
+    
     override var lastModified: Int = stageController.currentStage
     override var loweredUpTo: Int = stageController.currentStage
     override var values: Array<Carrier>? = null

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrValueParameter.kt

@@ -32,6 +32,11 @@ abstract class IrValueParameter : IrValueDeclaration(), IrSymbolDeclaration<IrVa
     abstract val varargElementType: IrType?
     abstract val isCrossinline: Boolean
     abstract val isNoinline: Boolean
+    // if true parameter is not included into IdSignature.
+    // Skipping hidden params makes IrFunction be look similar to FE.
+    // NOTE: it is introduced to fix KT-40980 because more clear solution was not possible to implement.
+    // Once we are able to load any top-level declaration from klib this hack should be deprecated and removed.
+    abstract val isHidden: Boolean
 
     abstract var defaultValue: IrExpressionBody?