I have the following test file:

#mode preservelf off
#mode user "$" "$" "{" "}{" "}$" "{" "}" "@" "~"
#mode meta "$" "$\w\n" "{" "}{" "}$\w\n" "{" "}"
$define{macro}{xyzzy}$
$macro$

Depending on the value of preservelf, the gpp outputs:

-with preservelf off-

\n
\n
\n
xyzzy\n

-with preservelf on-

\n
\n
\n
\n
xyzzy\n

I'm not sure if this is a bug or an omission on my side, but I'd like gpp to output only a single line (xyzzy\n).