Is folly buildable/usable with c++17?

[perseoGI]

Greetings from @conan-io,

We are trying to update folly recipe in Conan Center Index: conan-io/conan-center-index#27995 (comment)
While testing, we found that trying to compile folly with C++17 throws several errors, among them:

folly/debugging/exception_tracer/ExceptionTracerLib.cpp:78:10: error: no member named 'erase' in namespace 'std'
   78 |     std::erase(*callbacks, f);
      |     ~~~~~^

It seems folly is directly using C++20 features in their source files. So I guess at least C++20 is needed in order to compile the library.

But is folly still safe to be used (as a dependency) from a C++17 context? Menaning that if this library (nowadays) is still think to be used from C++17.

In the project README, it clearly says that it is a C++17 library

https://github.com/facebook/folly/blob/main/README.md?plain=1#L13

[mszabo-wikia]

There's at least #2477 as a known bug that'd cause issues in this situation.

Personally I think requiring C++20 would be the sustainable way forward; most other Meta C++ libraries such as fbthrift, HHVM, mcrouter, fizz etc. already require it.