IIRC I think there was a crate with a procedural macro like that which did something kinda similar to this. However currently that isn't really optimal for quite a few reasons: 1) having a procedural macro by itself pulls in extra dependencies, 2) it introduces extra work for the compiler so it does negatively impact the compile times (the procedural macros don't operate directly on the AST, so they have to parse the token stream into an AST, process it, serialize it back into a raw token stream, and the compiler has to parse it again), 3) Rust's current procedural macro machinery doesn't yet support emitting proper error messages from a procedural macro, so if you'll get an error or a warning from a piece of code generated by a procedural macro it will just point to the #[name_of_the_macro] annotation instead of the actual location where the issue originated from.
