On 17/06/2020 13:10, Ponnuvel Palaniyappan wrote: > The default C++ mode, when no -std= is specified, for g++ 9.3.0 is > gnu++14 (it's the same for g++ 10.1.0, too). > >> Looks like it is set by default, even when specifying the C++ standard version for g++ > Why this happens is explained in libstd++'s faq: > https://gcc.gnu.org/onlinedocs/libstdc++/faq.html#faq.predefined Fair enough