[IR] Add isAssignable property to IrValueParameter.

Use it to check that only the value parameters that are explicitly
marked assignable are assigned.

Currently, the only parameters marked assignable are those for
default argument stubs.

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

@@ -199,7 +199,8 @@ interface IrFactory {
         varargElementType: IrType?,
         isCrossinline: Boolean,
         isNoinline: Boolean,
-        isHidden: Boolean = false
+        isHidden: Boolean = false,
+        isAssignable: Boolean = false
     ): IrValueParameter
 
     // Bodies

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

@@ -39,6 +39,11 @@ abstract class IrValueParameter : IrValueDeclaration(), IrSymbolDeclaration<IrVa
     // Once we are able to load any top-level declaration from klib this hack should be deprecated and removed.
     abstract val isHidden: Boolean
 
+    // Parameters are not assignable by default. However, in the IR, assignments to parameters are used
+    // to implement default argument stubs. If the default value is to be used, the value is assigned
+    // to the parameter.
+    abstract val isAssignable: Boolean
+
     abstract var defaultValue: IrExpressionBody?
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyDeclarationBase.kt

@@ -32,7 +32,7 @@ interface IrLazyDeclarationBase : IrDeclaration {
     fun ReceiverParameterDescriptor.generateReceiverParameterStub(): IrValueParameter =
         factory.createValueParameter(
             UNDEFINED_OFFSET, UNDEFINED_OFFSET, origin, IrValueParameterSymbolImpl(this),
-            name, -1, type.toIrType(), null, isCrossinline = false, isNoinline = false
+            name, -1, type.toIrType(), null, isCrossinline = false, isNoinline = false, isAssignable = false
         )
 
     fun generateMemberStubs(memberScope: MemberScope, container: MutableList<IrDeclaration>) {

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/descriptors/IrBuiltIns.kt

@@ -80,7 +80,7 @@ class IrBuiltIns(
                 val valueParameterSymbol = IrValueParameterSymbolImpl(valueParameterDescriptor)
                 irFactory.createValueParameter(
                     UNDEFINED_OFFSET, UNDEFINED_OFFSET, BUILTIN_OPERATOR, valueParameterSymbol, Name.identifier("arg$i"), i,
-                    valueParameterType, null, isCrossinline = false, isNoinline = false
+                    valueParameterType, null, isCrossinline = false, isNoinline = false, isAssignable = false
                 ).apply {
                     parent = operator
                 }
@@ -165,7 +165,7 @@ class IrBuiltIns(
             val valueParameterSymbol = IrValueParameterSymbolImpl(valueParameterDescriptor)
             val valueParameter = irFactory.createValueParameter(
                 UNDEFINED_OFFSET, UNDEFINED_OFFSET, BUILTIN_OPERATOR, valueParameterSymbol, Name.identifier("arg0"), 0,
-                valueIrType, null, isCrossinline = false, isNoinline = false
+                valueIrType, null, isCrossinline = false, isNoinline = false, isAssignable = false
             )
 
             valueParameter.parent = operator

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/descriptors/IrFunctionFactory.kt

@@ -268,7 +268,8 @@ class IrFunctionFactory(private val irBuiltIns: IrBuiltIns, private val symbolTa
         val vDeclaration = irFactory.createValueParameter(
             offset, offset, classOrigin, vSymbol, Name.special("<this>"), -1, type, null,
             isCrossinline = false,
-            isNoinline = false
+            isNoinline = false,
+            isAssignable = false
         )
 
         if (vDescriptor is WrappedReceiverParameterDescriptor) vDescriptor.bind(vDeclaration)
@@ -332,7 +333,8 @@ class IrFunctionFactory(private val irBuiltIns: IrBuiltIns, private val symbolTa
                 val vDeclaration = irFactory.createValueParameter(
                     offset, offset, memberOrigin, vSymbol, Name.identifier("p$i"), i - 1, vType, null,
                     isCrossinline = false,
-                    isNoinline = false
+                    isNoinline = false,
+                    isAssignable = false
                 )
                 vDeclaration.parent = fDeclaration
                 if (vDescriptor is WrappedValueParameterDescriptor) vDescriptor.bind(vDeclaration)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/overrides/FakeOverrideCopier.kt

@@ -95,7 +95,8 @@ class FakeOverrideCopier(
             declaration.type.remapType(),
             declaration.varargElementType?.remapType(),
             declaration.isCrossinline,
-            declaration.isNoinline
+            declaration.isNoinline,
+            false
         ).apply {
             transformAnnotations(declaration)
             // Don't set the default value for fake overrides.

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

@@ -242,7 +242,7 @@ class DeclarationStubGenerator(
     internal fun generateValueParameterStub(descriptor: ValueParameterDescriptor): IrValueParameter = with(descriptor) {
         symbolTable.irFactory.createValueParameter(
             UNDEFINED_OFFSET, UNDEFINED_OFFSET, computeOrigin(this), IrValueParameterSymbolImpl(this), name, index, type.toIrType(),
-            varargElementType?.toIrType(), isCrossinline, isNoinline
+            varargElementType?.toIrType(), isCrossinline, isNoinline, false
         ).also { irValueParameter ->
             if (descriptor.declaresDefaultValue()) {
                 irValueParameter.defaultValue =

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

@@ -348,7 +348,8 @@ open class DeepCopyIrTreeWithSymbols(
             declaration.type.remapType(),
             declaration.varargElementType?.remapType(),
             declaration.isCrossinline,
-            declaration.isNoinline
+            declaration.isNoinline,
+            false
         ).apply {
             transformAnnotations(declaration)
             defaultValue = declaration.defaultValue?.transform()

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

@@ -524,7 +524,7 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
         renderFlagsList(
             "vararg".takeIf { varargElementType != null },
             "crossinline".takeIf { isCrossinline },
-            "noinline".takeIf { isNoinline }
+            "noinline".takeIf { isNoinline },
         )
 
     override fun visitLocalDelegatedProperty(declaration: IrLocalDelegatedProperty, data: Nothing?): String =

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

@@ -896,7 +896,7 @@ class SymbolTable(
         valueParameterFactory: (IrValueParameterSymbol) -> IrValueParameter = {
             irFactory.createValueParameter(
                 startOffset, endOffset, origin, it, nameProvider.nameForDeclaration(descriptor),
-                descriptor.indexOrMinusOne, type, varargElementType, descriptor.isCrossinline, descriptor.isNoinline
+                descriptor.indexOrMinusOne, type, varargElementType, descriptor.isCrossinline, descriptor.isNoinline, false
             )
         }
     ): IrValueParameter =