Require C++11?

[rrthomas]

C++11 support seems to be pretty much ubiquitous in deployed systems now; would it be reasonable to require it? I would be happy to provide a patch.

[wbraswell]

I reluctantly added C++11 support to my JPCRE2-utilizing codebase (https://github.com/wbraswell/rperl) a few years ago, but only after extensive researching & development which proved the necessity of doing so. In other words, I only added C++11 support because I had no choice.

The reason for this is simple but critical: backward compatibility. My code will no longer work on systems which do NOT support C++11, whether it is because the operating system is outdated or perhaps the administrator purposefully configured the OS without C++11 for whatever unknown reasons.

If JPCRE2 does not explicitly require C++11 features to work properly, then I believe the answer is no, we should NOT require C++11. It will not give us any benefit but will inevitably cause JPCRE2 to stop working on some non-C++11 systems.

[rrthomas]

@wbraswell Fine, but for how long? For example, the GNU Coding Standards dropped material specific to K&R C only a few years ago, which seems excessive backwards compatibility. I have assumed C99 to be a reasonable default in my projects for 5 years; that too seems rather conservative. No currently-supported GNU/Linux distro that I'm aware of lacks C++11 support, and I believe the same is true of macOS; I'm not sure about Windows. I'm aware there are other OSes, too!

Looking at https://en.cppreference.com/w/cpp/compiler_support one can see that more-or-less full C++11 support requires GCC 5, Clang 3.8, and MSVC 2015.

[wbraswell]

Backward compatibility should be maintained for as long as possible.
Just because some (or most) people want to upgrade, doesn't mean everyone wants to (or can) upgrade.