prevent date/time modification to update targets

[Cristian Zoicas]

Hello all

I  would like to know if it is possible to specify a prerequisite
for a target and for this prerequisite only its existence matters
when updating the target ( the modification time is ignored ).

In fact I want to create the following within my makefile:

out_directory
out_directory/file1.o
out_directory/file2.o

So I created the following makefile:

all: out_directory/file1.o out_directory/file2.o

out_directory/file1.o: source_file1.c out_directory
         $(CC) -o $@ -c $<

out_directory/file2.o: source_file2.c out_directory
         $(CC) -o $@ -c $<

out_directory:
        mkdir $@


For the first time when you run make all works ok. When you run it the
second  time 'file1.o' will  be rebuilt even if source_file1.c was not
changed.


this is because when you run make for the first time, the creation of
out_directory/file2.o changes the modification time of out_directory
and when you run it for the second time this triggers the compilation
of source_file1.c

Any help is welcomed.

cristian zoicas