KT-16439 Generated methods of data classes have no expression for default arguments

Provide default argument expressions for generated 'copy' declaration.

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt

@@ -51,6 +51,9 @@ fun <T : IrElement> IrStatementsBuilder<T>.defineTemporaryVar(value: IrExpressio
     return temporary.descriptor
 }
 
+fun IrBuilderWithScope.irExprBody(value: IrExpression) =
+        IrExpressionBodyImpl(startOffset, endOffset, value)
+
 fun IrBuilderWithScope.irReturn(value: IrExpression) =
         IrReturnImpl(startOffset, endOffset, context.builtIns.nothingType, scope.assertCastOwner(), value)
 

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrBuilder.kt

@@ -49,7 +49,7 @@ abstract class IrStatementsBuilder<out T : IrElement>(
     }
 
     protected abstract fun addStatement(irStatement: IrStatement)
-    protected abstract fun doBuild(): T
+    abstract fun doBuild(): T
 }
 
 open class IrBlockBodyBuilder(

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrMemberFunctionBuilder.kt

@@ -17,10 +17,13 @@
 package org.jetbrains.kotlin.ir.builders
 
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.impl.IrFunctionImpl
+import org.jetbrains.kotlin.ir.expressions.IrExpression
 
 class IrMemberFunctionBuilder(
         context: IrGeneratorContext,
@@ -30,10 +33,16 @@ class IrMemberFunctionBuilder(
         startOffset: Int = UNDEFINED_OFFSET,
         endOffset: Int = UNDEFINED_OFFSET
 ) : IrBlockBodyBuilder(context, Scope(function), startOffset, endOffset) {
-    inline fun addToClass(body: IrMemberFunctionBuilder.() -> Unit) {
-        val irFunction = IrFunctionImpl(startOffset, endOffset, origin, function)
-        body()
+    lateinit var irFunction: IrFunction
+
+    inline fun addToClass(body: IrMemberFunctionBuilder.(IrFunction) -> Unit) {
+        irFunction = IrFunctionImpl(startOffset, endOffset, origin, function)
+        body(irFunction)
         irFunction.body = doBuild()
         irClass.addMember(irFunction)
     }
+
+    fun putDefault(parameter: ValueParameterDescriptor, value: IrExpression) {
+        irFunction.putDefault(parameter, irExprBody(value))
+    }
 }