The translation units in C++ tend to pay this cost a number of times over because of the way header files are processed. With modules, this theoretically could

The translation units in C++ tend to pay this cost a number of times over because of the way header files are processed. With modules, this theoretically could start getting closer to Rust, but for large projects, C++ templates can still be orders of magnitude worse in terms of instantiation cost. This is partly why there are hacks like unity builds (not related to the engine, where all source is bundled into a single translation unit). These have plenty of drawbacks too so it's not a clear win. Adding to all of this, there are fancier mechanisms for template meta-programming like SFINAE rules + computed template values. Sure, it's "turing complete" but this is why we see such clever libraries with huge explosions in code generation size. I'm far from an expert in modern C++ features but it's clear that there is an entire interpreted programming language of templates bolted on the to the rest of C++. It reminds me of this post on a similar take on Haskell type level programming: https://aphyr.com/posts/342-typing-the-technical-interview https://aphyr.com/posts/342-typing-the-technical-interview (or similar feats by Oleg Kiselyov).