https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87656
--- Comment #2 from Manuel López-Ibáñez <manu at gcc dot gnu.org> --- From: https://gcc.gnu.org/wiki/DiagnosticsGuidelines As a rough guideline, a warning option should be: enabled by default if it has (almost) no false positives (e.g., -Woverflow); added to -Wall if it is generally useful with low number of false positives that are easy to work-around; added to -Wextra if it has quite a lot of false positives but they are still easy to work-around; Warning options should move up in this list when bugfixes reduce the number of false positives. These cases are not meant to be exhaustive: some options should never be enabled by other option if the warning is too specific (-Wdouble-promotion); other options are already controlled by options such as -Wpedantic and -Wformat and do not need to move up in this list (but they might if deemed useful). There are two types of bugs that should be added to this meta-bug: 1. Adding the warning to Wall/Wextra breaks GCC's build because of questionable GCC code (maybe not wrong, but avoiding the warning makes the code better). That is, the warning works as expected but GCC needs to be fixed. 2. The warning generates false positives in user code that are not easy to work-around. That is, the warning could be improved.
