Preprocessing C++ only

[Alan Larkin]

I cant figure out how to write a Makefile.am which directs that a %.cpp
be preprocessed to a %.i (and not compiled). Anybody got a suggestion?

Something like:

AM_CPPFLAGS = -I$(top_srcdir)/src @INCLTDL@
bin_PROGRAMS = Quadratic
Quadratic_SOURCES = Quadratic.cpp
Quadratic_CPPFLAGS = -E #-o Quadratic.i

chokes with the following:

<snip>
g++ -DHAVE_CONFIG_H -I. -I../src  -E    -g -O2 -MT Quadratic-Quadratic.o
-MD -MP -MF .deps/Quadratic-Quadratic.Tpo -c -o Quadratic-Quadratic.o
`test -f 'Quadratic.cpp' || echo './'`Quadratic.cpp

mv -f .deps/Quadratic-Quadratic.Tpo .deps/Quadratic-Quadratic.Po
/bin/sh ../libtool --tag=CXX   --mode=link g++  -g -O2   -o Quadratic
Quadratic-Quadratic.o

g++ -g -O2 -o Quadratic Quadratic-Quadratic.o Quadratic-Quadratic.o:
file not recognized: File format not recognized
collect2: ld returned 1 exit status
make[1]: *** [Quadratic] Error 1
<snip>

Thanks very much.