I'm using Fedora 38 and diffutils 3.9 installed. I also compiled from source and see the same issue.
file1: Here is some old line. file2: Here is some new line. % diff-3.8 -D NEW file1 file2 #ifndef NEW Here is some old line. #else /* NEW */ Here is some new line. #endif /* NEW */ % diff-3.9 -D NEW file1 file2: Here is some old line. Here is some new line.
