Wow, this is really good, there are still things I can learn.

C++ really has a lot of good things. It's just a shame it's so slow to compile.

I'm curious if anybody is working to make C++ faster to compile. Even if it was a subset of the language, with some features removed, it would be good enough for me.

* Compile with clang, link with mold or at least lld. mold can link gigabyte-sized binaries in, like, one second

* Use ninja instead of make

* Use PCH

* -gsplit-dwarf

This is all solid advice (particularly using a faster linker).

IME, the single best way to reduce your C++ compile times is to compile less code:

* Remove all unnecessary headers. Template expansion is slow, and preprocessing is even slower. Some of the standard includes (like `` and ``) are notorious for slowing individual translation units to a crawl. `#pragma once` for your own headers also helps with cpp-time performance.

* Forward-declare as much as you can. Forward type declarations mean that the compiler doesn't need to process all of `Foo` when it sees `Foo&` or `Foo`.

Use pImpl wherever you can (and makes sense). Private implementations similarly reduce the amount of code the compiler needs to analyze.

For better or worse, the current winds suggest that C++ compilation times will only continue to get worse (more constexpr/consteval, even more complex templating features/concepts, etc.).

> * Forward-declare as much as you can. Forward type declarations mean that the compiler doesn't need to process all of `Foo` when it sees `Foo&` or `Foo`.

I've found the include-what-you-use (IWYU) tool [1][2] can help immensely with automating this process, especially on large code-bases.

It uses LLVM/Clang to analyze a .cpp file / translation unit and produces the minimal subset of exactly which includes are necessary and what types can be forward declared.

[1] https://include-what-you-use.org/

[2] https://github.com/include-what-you-use/include-what-you-use