noreturn

 

For the latest documentation on Visual Studio 2017, see Visual Studio 2017 Documentation.

For the latest documentation on Visual Studio 2017, see noreturn on docs.microsoft.com.

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.

System_CAPS_ICON_note.jpg Note

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

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();  
}  

__declspec
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