GNU make behavior question

[Paul Lew]

Should make consider the prerequisite newer than target in case when
the file mod time for the prerequisite and the target are identical?

We have make file that uses 'cp -p' command to preserve file mod time.
The following is a simplified version of the makefile that illustrates
the problem:

> uname -a
SunOS cns-build2 5.6 Generic_105181-16 sun4u sparc

> make -v
GNU Make version 3.79.1, by Richard Stallman and Roland McGrath.
Built for sparc-sun-solaris2.6
Copyright (C) 1988, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 2000
        Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

Report bugs to <address@hidden>.

> cd /tmp

> touch bar

> cat > Makefile
foo:  bar
      cp -p bar foo

> make
cp -p bar foo

> make                  <== why it rebuild?
cp -p bar foo

> /usr/ccs/bin/make     <== Sun's make thinks differently
`foo' is up to date.

Which make behavior is the 'appropriate' behavior?  IMHO the Sun make
behaves the way most useful for the users.  Should this be filed as a
bug against GNU make, or a feature?

Thanks in advance..