On Tue, 21 Jan 2020 at 17:15, Anton Shepelev <anton.txt@xxxxxxxxx> wrote: > > Hello, all > > Shall -std=C++11 activate strict ANSI compliance by > means of __STRICT_ANSI__? Yes. It already does. > I have found only two op- > tions in the docs that activate it for C++ -- %-ansi > and -std=c++98. Are there other ones? All -std=c++NN options do. > I am asking this because in MinGW it does, so that, > for example, _fileno -- the MS analog of the POSIX > fileno, is unavailable in stdio.h with -std=C++11. > The MinGW maintainers maintain an opinion that > -std=C++11 turns on __STRICT_ANSI__, for which rea- > son a non-standard function shall not be available > in a standard header in standard C++11 mode, simply > because it is not part of the standard but an exten- > sion. > > On the other hand, fileno is available in stdio.h on > Linux with -std=C++11. Is it a defect, a courtesy > of the developers, or a requirement for a POSIX OS? That's because g++ on GNU/Linux also defines _GNU_SOURCE for ALL -std options (this is in addition to __STRICT_ANSI__ if you used a -std=c++NN option). Defining _GNU_SOURCE exposes all POSIX functions and GNU extensions. I intend to change that one day, so _GNU_SOURCE will never be automatically defined by the compiler. > In other words, is the programmer entitled to expect > fileno (_fileno) and other POSIX (Microsoft) exten- > sions in stdio.h while compiling with -std=C++11 on > a POSIX (Microsoft) OS, or is through the mere ne- > glect or coutesy of the developers that it *happens* > to be available? It happens to be available on GNU/Linux. That will change one day. It is wrong to expect it to be available when compiling with -std=c++11.
