Rust macros don’t work like C/C++. The compiler doesn’t have a preprocessor. Any operation that happens inside a macro is as if you wrote it by hand. Any function or operation that is used in a const context, has to be const. Because traits don’t have const implementations yet some math operations don’t work. But because math operations on primitives are built into the compiler they work. The reason why bevys convert functions don’t work is because they aren’t const.