Tag: visual-studio-2019

Visual Studio 2019 and [[nodiscard]] in its Default C++14 Mode

“Back-porting” and enabling [[nodiscard]] in C++14 code bases is a feature that can come in handy.

[[nodiscard]] is a feature that was added in C++17. However, it’s interesting to note that the Visual C++ compiler that comes with Visual Studio 2019 accepts [[nodiscard]] also when you compile C++ code in the default C++14 mode.

C++ project property page in VS 2019, showing the default C++14 mode selected.
Visual Studio 2019 C++ Project Properties

If, for some reason, you can’t compile your C++ code base with C++17 mode enabled, I would still suggest to use [[nodiscard]] in your C++ code, at least in places where it can help spotting subtle bugs (like in the cases suggested here).

C4834 warning message emitted by VC++ 2019 in its default C++14 mode, when the return value of a [[nodiscard]] function is discarded.
C4834 [[nodiscard]]-related warning message emitted by VC++ in default C++14 mode

You could even use some conditional compilation with preprocessor macros to enable [[nodiscard]] when compiling your C++ code with compilers like VC++ 2019 that support this feature, and expand that preprocessor macro to nothing in C++ compilers that don’t support it.