The `...` here is going to be Rust code that must be "run" at compile-time, because it can be used as a constant in the code -- for example, it can be used for array lengths.
Notice that CTFE is *not* the same as constant propagation: Constant propagation is an optimization pass done by LLVM that will opportunistically change code like `3 + 4` into `7` to avoid run-time work.
The `...` here is going to be Rust code that must be "run" at compile-time, because it can be used as a constant in the code -- for example, it can be used for array lengths.
Notice that CTFE is *not* the same as constant propagation: Constant propagation is an optimization pass done by LLVM that will opportunistically change code like `3 + 4` into `7` to avoid run-time work.