Inserting a '\' into a pattern rule command

[Martin Willers]

Hello,

in my Makefiles, the pattern rule for compiling C sources has the exact 
compiler command hidden behind a clean custom output like "[CC] main.o..."
to reduce visual clutter.
This is a stripped-down Makefile:

========================

CFLAGS += -DFOO -DBAR

%.o : %.c
        @echo "[CC] address@hidden"; \
        $(CC) -c -o $@ $(CFLAGS) $<

test: test.o
        @echo "[LD] address@hidden"
        @#actually link target here

========================

Now, from time to time I'd like to see the exact compiler command-line,
for example for inspecting certain CFLAGS entries which may not be given that 
obvious like in the example above.
For this, I'd need to remove the '\' character in the middle line of the 
pattern rule, so that the $(CC) line is not hidden behind the '@' anymore.

Now my question is: Can I achieve this without having to find that '\' 
character and remove it inbetween the pattern rule? I'd like to be able to 
activate this feature by some environment variable, like:
  $ SHOW_CMD=1 make

I was trying to define some variable with a '\' in it and place it there 
programmatically, but I couldn't get it to work:

## tried both with and without a trailing space in this var,
## and with one as well as two '\' chars
BS:=\ 

%.o : %.c
        @echo "[CC] address@hidden"; $(BS)
        $(CC) -c -o $@ $(CFLAGS) $<

$ make
[CC] test.o...
/bin/sh:  : command not found
make: *** [test.o] Fehler 127


Surely this must be possible?

-- 
 Martin Willers