Yeah, I really missed ubiquitous C preprocessor macros in C++, so let's bring them back, but now inside string literals. Sweet.

Seriously, I just keep being amazed that people are running with the idea of having a full-blown untyped and unchecked formatting mini language (that's what libfmt, which became C++20 format, literally calls it) inside string literals — i.e., the part of the source code that you're specifically telling the compiler to not treat as code.

Think about it for a minute.