🚀 go-pugleaf

GNU's cpp expands macros, but not in the way that I want.  It adds
a space after the macro expansion (which is documented in cpp.info,
node Output), and this space has caused a problem.

I recently built X11R5 for the first time using (mostly) gcc-2.1.
X uses cpp's macro expansion facility to "fill-in-the-blanks" for
some implementation-dependent items, in particular the directory for
xdm's configuration data.  cpp left a space in the middle of a path
name.

The code that produces xdm-config is in ./mit/clients/xdm/config/Makefile:

xdm-config:: xdm-conf.cpp
	$(RM) $@
	$(CPP) -DXDMDIR=$(XDMDIR) <xdm-conf.cpp | sed -e '/^#  *[0-9][0-9]*  *.*$$/d' -e '/^XCOMM$$/s//#/' -e '/^XCOMM[^a-zA-Z0-9_]/s/^XCOMM/#/' >$@

where XDMDIR has been defined as something like `/usr/X11R5/lib/X11/xdm'.
Here's a simpler example that shows the effect:

Put the following in Makefile:

CPP = /usr/gnu/lib/gcc-lib/sparc-sunos4.1.1/2.1/cpp
# CPP = /usr/lib/cpp

xdm-config:: xdm-conf.cpp
	rm -f $@
	$(CPP) -DXDMDIR=floob <xdm-conf.cpp >$@

And here's a piece of xdm-conf.cpp:

DisplayManager.errorLogFile:	XDMDIR/xdm-errors
DisplayManager.pidFile:		XDMDIR/xdm-pid
DisplayManager.keyFile:		XDMDIR/xdm-keys

Invoking make with Makefile as above, the results are:

# 1 ""
DisplayManager.errorLogFile:    floob /xdm-errors
DisplayManager.pidFile:         floob /xdm-pid
DisplayManager.keyFile:         floob /xdm-keys

With the other CPP line enabled, the results are:

# 1 "" 
DisplayManager.errorLogFile:    floob/xdm-errors
DisplayManager.pidFile:         floob/xdm-pid
DisplayManager.keyFile:         floob/xdm-keys

The first output line is the result of skipping the sed script.  I ran
this on a SPARC 4/60 w/ SunOS 4.1.1, and also tried it on a VAX runing
ULTRIX 4.1 with the same results: GNU cpp added a space, and the native
system cpp gave the results I wanted.

Is there any (convenient) way to change GNU cpp's action of adding
a space after macro expansion?

	-- Vince


-- 
Vince Tessier			Dairyland Fertilizer & Supply
vtessier@vela.acs.oakland.edu	"Purveyors of Bullshit to the Trade"