Yup. Unfortunately the project I'm working on does not have any debug info. There are not even lingering __FILE__ strings anywhere. Just picking out the TU bounds has been a chore!
It's a huge benefit that things like the OS and SDK are known and predictable. This got me a foothold. Otherwise I would have gotten nowhere.
I'm still impressed that this decomp has macros (fully lost in the assembly) and nearly-100% meaningful variable names and struct layouts. That's not easy!