GCC 7.x is now out alongside Visual Studio 2018. This means that `sol release v2.20.1`_ is the current version of the code targeted at the older compilers not listed below. Newer code will be targeted at working with the following compilers and leveraging their features, possibly taking advantage of whatever C++17 features are made available by the compilers and standard libraries bundled by-default with them.
**This does not mean we are immediately abandoning older compilers.** We will update this page as relevant bugfixes are backported to the v2.x.x releases. Remember that sol3 is feature-complete: there is nothing more we can add to the library at this time with C++11/C++14 compiler support, so your code will be covered for a long time to come.
Note that Visual Studio's 2018 Community Edition is absolutely free now, and installs faster and easier than ever before. It also removes a lot of hacky work arounds and formally supports decltype SFINAE.
For individiauls who use :doc:`usertypes<api/usertype>` a lot, they can find their compilation times increase. This is due to C++11 and C++14 not having very good facilities for handling template parameters and variadic template parameters. There are a few things in cutting-edge C++17 and C++Next that sol can use, but the problem is many people cannot work with the latest and greatest: therefore, we have to use older techniques that result in a fair amount of redundant function specializations that can be subject to the pickiness of the compiler's inlining and other such techniques.
* When you bind lots of usertypes, put them all in a *single* translation unit (one C++ file) so that it is not recompiled multiple times over, only to be discarded later by the linker.
- Remember that the usertype binding ends up being serialized into the Lua state, so you never need them to appear in a header and cause that same compilation overhead for every compiled unit in your project.
* Consider placing groups of bindings in multiple different translation units (multiple C++ source files) so that only part of the bindings are recompiled when you have to change the bindings.
- Avoid putting your bindings into headers: it *will* slow down your compilation
* If you are developing a shared library, restrict your overall surface area by specifically and explicitly marking functions as visible and exported and leaving everything else as hidden or invisible by default
* For people who already have a tool that retrieves function signatures and arguments, it might be in your best interest to hook into that tool or generator and dump out the information once using sol3's lower-level abstractions. An `issue describing preliminary steps can be found here`_.
The next step for Sol from a developer standpoint is to formally make the library a C++17 one. This would mean using Fold Expressions and several other things which will reduce compilation time drastically. Unfortunately, that means also boosting compiler requirements. While most wouldn't care, others are very slow to upgrade: finding the balance is difficult, and often we have to opt for backwards compatibility and fixes for bad / older compilers (of which there are many in the codebase already).
Hopefully, as things progress, we move things forward.
