Organize code to minimize header dependencies and improve compilation times. Use forward declarations instead of includes when possible, avoid unnecessary dependencies, and follow proper header organization patterns. Key practices: - Use forward declarations in headers when you only need to declare pointers or references to a type - Implementation files (.cpp) should contain the actual includes, while headers (.h) should minimize dependencies - Avoid including heavy headers when lighter alternatives exist - Never use `static` declarations in header files as they create separate instances in each translation unit - Organize includes to separate interface declarations from implementation dependencies Example: ```cpp // Good: Use forward declaration in header // MyClass.h class WarnUnusedResultAttr; // Forward declaration class MyClass { WarnUnusedResultAttr* attr; }; // MyClass.cpp - actual include in implementation #include "clang/AST/Attr.h" // Bad: Heavy include in header // MyClass.h #include "clang/AST/Attr.h" // Unnecessary dependency ``` This approach reduces compilation times, minimizes rebuild cascades when headers change, and creates cleaner module boundaries.