No, it is the way.
Edit: no one has time for inventing unique names for include guards.
#pragma once is broken by design
I think you're suggesting that you don't need to make up the names for include guards because all tools / IDEs for C++ write them for you automatically anyway. But that isn't my experience. Many IDEs don't write include guards for you automatically ... because everybody uses #pragma once already.
> #pragma once is broken by design
I think you're referring to the historical problem with #pragma once, which is that it can be hard for the compiler to identify what is really the same file (and therefore shouldn't be included a second time). If you hard link to the same file, or soft link to it, is it the same? What if the same file is mapped to two different mount points? What if genuinely different files have the same contents (e.g., because the same library is included from two different installation paths)? In practice, soft/hard links to the same file are easily detectable, and anything more obscure indicates such a weird problem with your setup that you surely have bigger issues. #pragma once is fine.
(Historically, it also had the benefit that compilers would know not to even re-read the header, whereas with traditional include guards they would need to re-include the file (e.g. in case the whole file is not wrapped in the #ifdef, or in case something else has undefined it since) only to then discard the contents. I've even seen coding guidelines requiring external include guards wrapped around every use of headers with #include <...>. Yuck! But modern compilers can work out when include guards are meant to mean that so today that difference probably no longer exists.)
They don't. They are not C++ and at most they are compiler-specific.
It's fine if you opt to not write C++ and instead target specific compilers instead. Just don't pretend it's not frowned upon or kosher.
Since you seem to be more knowledgeble about this, I'm curious to know which C++ compilers lack support? I know that at least the 3 big ones do (GCC, Clang, and MSVC) and they have for a very long time.
No, this is completely wrong. Pragma once is non-standard compiler directive. It might be supported by some compilers such as msvc but technically it is not even C++.
There are only two options: include guards, and modules.
The whole point is that it's not supported and it's not standard, thus using #pragma once needlessly introduced the risk of having the code break.
You should ask yourself what are you doing and why are you using non-standard constructs that may or may not work, specially when it's rather obvious and trivial to just use include guards. Using #pragma once isn't even qualify as being clever to gain anything.
If the standards still don't have a proper replacement for include guards, then too bad for the standards. The C++ standard wasn't aware of multithreading before C++11, this didn't stop people from writing multithreaded programs.
As to why - #pragma once is just cleaner to look at.
It does with modules... and in ten year if modules support is widespread, I'll consider stoping using pragma once.
Plus, it's nicer to read than #ifndef FOO_BAR_BAZ_PROJ_DIR1_DIR2_DIR3_FILE_H
#endif /* FOO_BAR_BAZ_PROJ_DIR1_DIR2_DIR3_FILE_H */
On every file.
Not being part of the official standard doesn't necessarily mean it's not well supported.
I have genuinely encountered problems due to traditional include guards: in a project I worked on, they had been copied and pasted to one of the headers without being changed properly, but not included in the same translation unit so it went undetected. I noticed it when I needed to use them differently, at which point I got a mysterious compiler error. Admittedly, that was easily fixed, but naturally I checked if a similar problem existed in other files and sure enough it did. Now I need to decide whether to fix all those too and where to draw the line. Time and mental energy wasted for no reason.
I don't want to hear about how extra tooling could have avoided the problem. Using pragma once would have avoided the problem! It's simpler, less effort in the first place, needs no extra tooling and works everywhere in practice.