exit: redefinition; '__declspec(noreturn)' or '[[noreturn]]'

The error message "redefinition; '__declspec(noreturn)' or '[[noreturn]]'" in C++ typically occurs when the exit function is redefined with conflicting attributes.

To understand this error message, let's break it down step by step:

  1. Redefinition: The error message indicates that there is a redefinition of the exit function. This means that the exit function is being declared or defined more than once in your code.

  2. '__declspec(noreturn)' or '[[noreturn]]': The error message further specifies that the conflicting redefinition involves the attributes '__declspec(noreturn)' or '[[noreturn]]'. These attributes are used to indicate that a function does not return to its caller.

  3. '__declspec(noreturn)': This attribute is a Microsoft-specific extension and can be used to specify that a function does not return.

  4. '[[noreturn]]': This attribute is a C++11 standard attribute and can also be used to specify that a function does not return.

Now, based on the error message, you should check your code for any conflicting definitions or declarations of the exit function. Make sure that the function is defined or declared only once in your code, and that the attributes '__declspec(noreturn)' or '[[noreturn]]' are used consistently.

Here is an example of how the exit function can be correctly declared with the [[noreturn]] attribute:

[[noreturn]] void exit(int status);

By ensuring that the exit function is defined or declared only once with the correct attributes, you can resolve the "redefinition; '__declspec(noreturn)' or '[[noreturn]]'" error in C++.