Is there a way to tell Perforce to leave text files alone without setting the file-type as binary? Or barring that, is there a way to tell the Perforce client to diff binaries?
I have just come across exactly the same problem, but have a better solution that does not involve changing client specs (which are international, and not all of which I have write access to).
All of our clients are Windows PCs, but Cygwin is included within the Perforce Depot. Cygwin is a Windows implementation of Unix, and requires that text files use LF for line endings.
A possible solution for older versions of Cygwin is to mount the root using the "text" option, meaning that files can have CR+LF line endings. However, on upgrading to Cygwin 1.7.9, this no longer worked, as mounts are transient unless they are written into /etc/fstab. I did not manage to make this work.
Luckily, the Perforce Guru sitting next to me came up with the solution of changing the filetype to binary+D, which uses the same RCS incremental patch storage as text files, but without the automatic line ending conversion.
I can diff these "text" files successfully between my local workspace and the depot.