title	noreturn | Microsoft Docs
ms.custom
ms.date	11/04/2016
ms.technology	cpp-language
ms.topic	language-reference
f1_keywords	noreturn_cpp
dev_langs	C++
helpviewer_keywords	__declspec keyword [C++], noreturn noreturn __declspec keyword
ms.assetid	9c6517e5-22d7-4051-9974-3d2200ae4d1d
author	mikeblome
ms.author	mblome
ms.workload	cplusplus

noreturn

Microsoft Specific

This __declspec attribute tells the compiler that a function does not return. As a consequence, the compiler knows that the code following a call to a __declspec(noreturn) function is unreachable.

If the compiler finds a function with a control path that does not return a value, it generates a warning (C4715) or error message (C2202). If the control path cannot be reached due to a function that never returns, you can use __declspec(noreturn) to prevent this warning or error.

Note

Adding __declspec(noreturn) to a function that is expected to return can result in undefined behavior.

Example

In the following sample,the else clause does not contain a return statement. Declaring fatal as __declspec(noreturn) avoids an error or warning message.

// noreturn2.cpp
__declspec(noreturn) extern void fatal () {}

int main() {
   if(1)
     return 1;
   else if(0)
     return 0;
   else
     fatal();
}

See also

__declspec
Keywords