Building C++20 Modules with Xmake

Xmake has first-class C++20 modules support across GCC, Clang, and MSVC. It handles the BMI (Built Module Interface) cache, dependency scanning, and per-compiler flag differences automatically — you mostly just point it at the files and enable the policy.

1. Prerequisites

• C++20 language version.
• A new-ish compiler: GCC 14+, Clang 16+ (better: 17+), MSVC 19.34+ (VS 2022 17.4+).
• build.c++.modules policy enabled.

2. Minimal executable with modules

Project layout: