Client project post-mortem

The 2024–2025 client project at a hedge fund has been pretty intense. I worked with two teams and three C++ code bases, of which one was new, around 1.5 years old, and the others two much more 'mature'. Both teams were excellent. Absolutely fantastic colleagues, very friendly and professional, a pleasure to work with.

Some random thoughts:

• C++23 is really nice.
  • Couldn't use modules yet, mainly because of several GCC 14 showstopper bugs. Clang 19 worked fine in a proof-of-concept scenario.
  • The non-standard #pragma once has won.
• If you need to program a web server in C++, Drogon is not a bad choice.
• CMake is a terrible mess and everything I learnt about it was against my will. Unfortunately, we are stuck with it.
  • Use CMake presets to simplify your life.
  • Treat CMake as the source of truth and avoid any complex build scripts.
• Bazel is probably the most capable C++ build system at the moment.
• VSCode as a C++ IDE is pretty good, actually. Never expected to say that.
  • Use clangd extension instead of Microsoft IntelliSense.
  • Have plenty of RAM.
• Devcontainers can be fiddly, but when they work they are fantastic.
• CLion is great, but
  • Devcontainers support was completely broken last time I checked, around September 2025
  • Have at least 64GB of RAM.
• Builds have to be isolated.
  • A single configuration must build into a single build directory.
  • During the build the source tree must not be modified, no files must be added to it outside the build tree, including any generated sources.
• Builds and unit tests have to be fast.
  • Don't treat slow regression tests as unit tests.
  • Use mold linker which is blazing fast even compared with lld.
  • Use ccache with remote backend and distcc.
  • Use Clang Build Analyzer to optimise the build.
• Releases must require as few manual steps as possible. Ideally, to release software you should execute a single command.
  • It should be quick and easy to release a one-line PR.
  • Try not to mix different changes in one PR. That includes formatting and other no-op changes.
  • Use clang-format with pre-commit hooks and your editor to keep code tidy and avoid pointless style discussions.
• Kubernetes is great, but requires mad YAML skills.
• Life is so much easier when you don't have to support Windows.
• While AI was being heavily pushed from above, I did not use it. Judging by how other developers used it, I decided I don't want to outsource my thinking to chatbots just yet.