Microsoft Specific

A __declspec extended attribute which can be used in the declaration of functions.

return-type __declspec(nothrow) [call-convention] function-name ([argument-list])

We recommend that all new code use the noexcept operator rather than __declspec(nothrow).

This attribute tells the compiler that the declared function and the functions it calls never throw an exception. However, it does not enforce the directive. In other words, it never causes std::terminate to be invoked, unlike noexcept, or in std:c++17 mode (Visual Studio 2017 version 15.5 and later), throw().

With the synchronous exception handling model, now the default, the compiler can eliminate the mechanics of tracking the lifetime of certain unwindable objects in such a function, and significantly reduce the code size. Given the following preprocessor directive, the three function declarations below are equivalent in /std:c++14 mode:

#define WINAPI __declspec(nothrow) __stdcall

void WINAPI f1();
void __declspec(nothrow) __stdcall f2();
void __stdcall f3() throw();

In /std:c++17 mode, throw() is not equivalent to the others that use __declspec(nothrow) because it causes std::terminate to be invoked if an exception is thrown from the function.

The void __stdcall f3() throw(); declaration uses the syntax defined by the C++ standard. In C++17 the throw() keyword was deprecated.

END Microsoft Specific

__declspec
noexcept
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