Oh, you got me there, cygwin

I wonder if there's an actual technical reason for this. Especially since the auto option cannot possibly work with those constraints. Hilarious.

$ u2d --help
u2d is part of cygutils version 1.4.4
converts the line endings of text files from
UNIX style (0x0a) to DOS style (0x0d 0x0a)

Usage: u2d [OPTION...] [input file list...]

Main options (not all may apply)
-A, --auto     Output format will be the opposite of the autodetected source
               format
-D, --u2d      Output will be in DOS format
--unix2dos     Output will be in DOS format
-U, --d2u      Output will be in UNIX format
--dos2unix     Output will be in UNIX format
--force        Ignore binary file detection
--safe         Do not modify binary files

Help options
-?, --help     Show this help message
--usage        Display brief usage message
--version      Display version information
--license      Display licensing information

Other arguments
[input file list...]       for each file listed, convert in place.
                           If none specified, then use stdin/stdout

$ u2d -U messages_de.properties
u2d: cannot accept any conversion type argument other
than --u2d (--unix2dos, -D) when the program is called with this name

$ d2u -U messages_de.properties
messages_de.properties: done.