Older/ReSharper20163Cpp/Cpp17NestedNamespace.cpp (11 lines of code) (raw):

#include "stdafx.h" // Convert to nested namespace definition (C++17) // // Place text caret on `One` below, Alt+Enter and select "Convert to nested namespace definition" // // Requires /std:c++latest set in C/C++ | Command Line | Additional Options project properties namespace One { namespace Two { int GetMeaningOfLife() { return 42; } } }