Explore the challenges and solutions of implementing C++11 features in Qt5 while maintaining compatibility with older compilers in this comprehensive CppNow conference talk. Dive into the decision-making process behind selecting which C++11 features to adopt and how to retain compatibility with C++98/C++03 compilers. Gain insights into the mechanisms put in place to support various compilers in both C++98/03 and C++11 modes. Discover practical guidelines for C++ developers facing the task of porting libraries and applications to C++11 while maintaining C++03 compatibility. Learn about specific C++11 language features implemented in Qt5, including template friends, alignment, atomics, const expressions, static initialization, initializer lists, move semantics, and ref qualifiers. Understand the complexities of targeting a large C++ class library at multiple language standards simultaneously and the innovative solutions employed by the Qt development team.