Re: What does cl's /FD option do?

This is with VS2K5Pro SP1.

I did the following experiment: create a Win32 Console project, check
the box for ?ATL Headers? in the Application Settings dialog and
compile the resulting stub program. Look at the build log HTML.

Among other options, it specifies ?/FD? which as far as I can tell is
undocumented. And ?/TP .\stdafx.cpp? where /TP is supposed to be
?treat all files as C++? and is not supposed to take a filename
argument (/Tpfilespec is the one that means ?treat the following file
as C++ no matter how it?s named?).

I can find some ancient posts that say /FD was for generating makefile
dependencies (this is like, 2001 or so) and another claim (from 2004 I
think) that it was for enabling minimal rebuild. Exporting makefiles
went away long ago, and minimal rebuild is now /Gm.

Apparently this has been undocumented for a long time... these old
posts also complain about /FD not showing up in the output of cl /?.

And it does seem to be an option that does something... if you stick a
random unused letter in the flags (/K, say) cl will issue warning
D9002 and say that it's "ignoring unknown option '/K'" but it doesn't
do that with /FD.

Anybody know what this is?