[Bug debug/77985] DW_AT_comp_dir is omitted when filename is absolute and the file does not contain a specific typedef

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77985

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
So I just fixed the bug here, but yes, I don't know about the design decision. 
I suppose CWD was decided to be useless in case of an absolute path to the
file.

I don't think the debug info preserves -I paths in any standard way, so what's
exactly the reason you consider CWD not redundant here?  [we could rewrite the
file-name to relative to CWD]