When @command{windres} reads an @code{rc} file, it runs it through the C
preprocessor first. This option may be used to specify the preprocessor
to use, including any leading arguments. The default preprocessor
-argument is @code{gcc -E -xc-header -DRC_INVOKED}.
+argument is @code{gcc}.
@item --preprocessor-arg @var{option}
When @command{windres} reads an @code{rc} file, it runs it through
text to be passed to preprocessor on its command line.
This option can be used multiple times to add multiple options to the
preprocessor command line.
+If the @option{--preprocessor} option has not been specified then a
+default set of preprocessor arguments will be used, with any
+@option{--preprocessor-arg} options being placed after them on the
+command line. These default arguments are @code{-E -xc-header
+-DRC_INVOKED}.
@item -I @var{directory}
@itemx --include-dir @var{directory}