What does it mean to be a "fictitious module"? I thought at first this meant that it isn't really defined as a module but through other means, but the linked source code has a "module Crystal::Macros" line, so it looks pretty real to me.
You might notice the very top of the file that skips it unless docs are being generated. Or the fact that every function is completely empty.
It’s a module that exists solely for generating documentation.