Huge +1.
I've encountered this limitation when working on a #context macro. This macro aims to combine #file, #function, #line, #column, and similar identifiers into a single structure, offering a more convenient way for propagating source location information. This would let us realize @davedelong's original idea. The challenge lies in the requirement for default arguments to be literals, which complicates the process. However, it's feasible to encapsulate this information into a single string literal to meet this requirement.