Default arguments lowering should not touch inline functions.

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/DefaultArgumentStubGenerator.kt

@@ -58,7 +58,7 @@ class DefaultArgumentStubGenerator internal constructor(val context: Context): D
     private fun lower(irFunction: IrFunction): List<IrFunction> {
         val functionDescriptor = irFunction.descriptor
 
-        if (hasNotDefaultParameters(functionDescriptor))
+        if (!functionDescriptor.needsDefaultArgumentsLowering)
             return irFunction.singletonList()
 
         val bodies = functionDescriptor.valueParameters
@@ -222,7 +222,7 @@ class DefaultParameterInjector internal constructor(val context: Context): BodyL
             override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall): IrExpression {
                 super.visitDelegatingConstructorCall(expression)
                 val descriptor = expression.descriptor
-                if (hasNotDefaultParameters(descriptor))
+                if (!descriptor.needsDefaultArgumentsLowering)
                     return expression
                 val argumentsCount = argumentCount(expression)
                 if (argumentsCount == descriptor.valueParameters.size)
@@ -246,7 +246,7 @@ class DefaultParameterInjector internal constructor(val context: Context): BodyL
                 super.visitCall(expression)
                 val functionDescriptor = expression.descriptor as FunctionDescriptor
 
-                if (hasNotDefaultParameters(functionDescriptor))
+                if (!functionDescriptor.needsDefaultArgumentsLowering)
                     return expression
 
                 val argumentsCount = argumentCount(expression)
@@ -326,8 +326,8 @@ class DefaultParameterInjector internal constructor(val context: Context): BodyL
     private fun log(msg: String) = context.log("DEFAULT-INJECTOR: $msg")
 }
 
-private fun hasNotDefaultParameters(descriptor: CallableDescriptor) = descriptor.valueParameters.none { it.hasDefaultValue() }
-
+private val CallableMemberDescriptor.needsDefaultArgumentsLowering
+    get() = valueParameters.any { it.hasDefaultValue() } && !(this is FunctionDescriptor && isInline)
 
 private fun FunctionDescriptor.generateDefaultsDescription(context: Context): FunctionDescriptor {
     return context.ir.defaultParameterDescriptorsCache.getOrPut(this) {

runtime/src/main/kotlin/kotlin/text/Strings.kt

@@ -312,8 +312,10 @@ public inline fun String.subSequence(start: Int, end: Int): CharSequence = subSe
  * @param startIndex the start index (inclusive).
  * @param endIndex the end index (exclusive). If not specified, the length of the char sequence is used.
  */
+// TODO: uncomment as soon as inlining works for stdlib.
+@Fixme
 @kotlin.internal.InlineOnly
-public inline fun CharSequence.substring(startIndex: Int, endIndex: Int = length): String = subSequence(startIndex, endIndex).toString()
+public /*inline*/ fun CharSequence.substring(startIndex: Int, endIndex: Int = length): String = subSequence(startIndex, endIndex).toString()
 
 /**
  * Returns a substring of chars at indices from the specified [range] of this char sequence.