To allow the user to customize the C++ code that QDoc sees, so as to be able to work-around some limitations on QDoc itself, QDoc defines two symbols: Q_QDOC and Q_CLANG_QDOC, both of which are "true" during an entire execution of QDoc. At a certain point in time, QDoc allowed the user the choice between a custom C++ parser and a Clang based one. The Q_QDOC symbol would always be defined while the Q_CLANG_QDOC symbol would be defined only when the Clang based parser was chosen. In more recent times, QDoc always uses a Clang based parser, such that both Q_CLANG_QDOC and Q_QDOC are always defined, making them equivalent. To avoid using different symbols, and the possible confusion and fragmentation that derives from it, all usages of Q_CLANG_QDOC are now replaced by the equivalent usages of Q_QDOC. Change-Id: I5810abb9ad1016a4c5bbea99acd03381b8514b3f Reviewed-by: Kai Koehne <kai.koehne@qt.io>