Add minor improvements to psi2ir and IR utilities:

* Generate missing IR parameter declarations in external stubs
* Use origin = FAKE_OVERRIDE in external IR stubs for fake overrides
* Set .parent in external IR stubs
* Set .parent in IR generated by some utility methods

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -113,6 +113,7 @@ fun IrClass.addSimpleDelegatingConstructor(superConstructorSymbol: IrConstructor
                 )
         )
 
+        constructor.parent = this
         this.declarations.add(constructor)
     }
 }

compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/util/IrUtils.kt

@@ -126,7 +126,9 @@ fun IrFunction.createParameterDeclarations() {
             innerStartOffset(this), innerEndOffset(this),
             IrDeclarationOrigin.DEFINED,
             this
-    )
+    ).also {
+        it.parent = this@createParameterDeclarations
+    }
 
     dispatchReceiverParameter = descriptor.dispatchReceiverParameter?.irValueParameter()
     extensionReceiverParameter = descriptor.extensionReceiverParameter?.irValueParameter()
@@ -140,7 +142,9 @@ fun IrFunction.createParameterDeclarations() {
                 innerStartOffset(it), innerEndOffset(it),
                 IrDeclarationOrigin.DEFINED,
                 it
-        )
+        ).also { typeParameter ->
+            typeParameter.parent = this
+        }
     }
 }
 

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

@@ -55,6 +55,7 @@ class IrBuiltIns(val builtIns: KotlinBuiltIns) {
     private fun addStubToPackageFragment(descriptor: SimpleFunctionDescriptor): IrSimpleFunction {
         val irSimpleFunction = stubBuilder.generateFunctionStub(descriptor)
         irBuiltInsExternalPackageFragment.declarations.add(irSimpleFunction)
+        irSimpleFunction.parent = irBuiltInsExternalPackageFragment
         return irSimpleFunction
     }
 

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

@@ -71,20 +71,34 @@ class DeclarationStubGenerator(
         }
 
     fun generateFunctionStub(descriptor: FunctionDescriptor): IrSimpleFunction =
-        symbolTable.declareSimpleFunctionWithOverrides(UNDEFINED_OFFSET, UNDEFINED_OFFSET, origin, descriptor.original).also { irFunction ->
+        symbolTable.declareSimpleFunctionWithOverrides(
+            UNDEFINED_OFFSET, UNDEFINED_OFFSET,
+            if (descriptor.kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE) {
+                IrDeclarationOrigin.FAKE_OVERRIDE
+            } else {
+                origin
+            },
+            descriptor.original
+        ).also { irFunction ->
             generateTypeParameterStubs(descriptor.typeParameters, irFunction)
-            generateValueParametersStubs(descriptor.valueParameters, irFunction)
+            generateValueParametersStubs(irFunction)
         }
 
     private fun generateConstructorStub(descriptor: ClassConstructorDescriptor): IrConstructor =
         symbolTable.declareConstructor(UNDEFINED_OFFSET, UNDEFINED_OFFSET, origin, descriptor.original).also { irConstructor ->
-            generateValueParametersStubs(descriptor.valueParameters, irConstructor)
+            generateValueParametersStubs(irConstructor)
         }
 
-    private fun generateValueParametersStubs(valueParameters: Collection<ValueParameterDescriptor>, function: IrFunction) {
-        valueParameters.mapTo(function.valueParameters) { generateValueParameterStub(it) }
+    private fun generateValueParametersStubs(function: IrFunction) {
+        val descriptor = function.descriptor
+        function.dispatchReceiverParameter = descriptor.dispatchReceiverParameter?.generateReceiverParameterStub()
+        function.extensionReceiverParameter = descriptor.extensionReceiverParameter?.generateReceiverParameterStub()
+        descriptor.valueParameters.mapTo(function.valueParameters) { generateValueParameterStub(it) }
     }
 
+    private fun ReceiverParameterDescriptor.generateReceiverParameterStub(): IrValueParameter =
+        IrValueParameterImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, origin, this)
+
     private fun generateValueParameterStub(descriptor: ValueParameterDescriptor): IrValueParameter =
         IrValueParameterImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, origin, descriptor).also { irValueParameter ->
             if (descriptor.declaresDefaultValue()) {
@@ -108,6 +122,7 @@ class DeclarationStubGenerator(
             }
 
             generateTypeParameterStubs(descriptor.declaredTypeParameters, irClass)
+            irClass.thisReceiver = descriptor.thisAsReceiverParameter.generateReceiverParameterStub()
             generateChildStubs(descriptor.constructors, irClass)
             generateMemberStubs(descriptor.defaultType.memberScope, irClass)
             generateMemberStubs(descriptor.staticScope, irClass)

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

@@ -52,6 +52,6 @@ class ExternalDependenciesGenerator(val symbolTable: SymbolTable, val irBuiltIns
             topLevelDescriptors.mapTo(irExternalPackageFragment.declarations) {
                 stubGenerator.generateMemberStub(it)
             }
-        }
+        }.patchDeclarationParents()
 
 }