makefile automatic variables question

[tronix]

Hi all,

I need to write makefile for my project. I wrote some basic makefiles, and
never used automatic variables. But the makefile that my project needs is a
bit more complex (has to be recursive and few other stuff). I'm learning how
to write such makefiles. While learning I came across the automatic
variables and tried them on a simple code (file name: test.c).... I wrote
the following makefile:

EXEC = test
OBJS = test.o

all : $(EXEC)
$(EXEC) : $(OBJS)

% : %.o
        echo "First line\n"
        gcc $< -o $@    


# %.o : %.c
#       echo "This is second line\n"
#       gcc -c $<

.PHONY : clean
clean :
        -rm -f $(EXEC) $(OBJS)

With the lines that are commented I'm not providing any rule to make the
object files. Hence when I execute make I expected this to give me error,
but this proceeds smoothly with following output:

cc    -c -o test.o test.c
echo "First line\n"
First line\n
gcc test.o -o test      

does make "know" howto get .o files even with out specifying. Why doesn't
this give me an error as I expected. 

Thanks.

-----
"tron"ix
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