Re: multi-target with -j2

On Sun, Jun 8, 2025 at 12:35 AM <[email protected]> wrote:
> I am a happy user of make (various implementations) for 25 years. Today I
> learned that "multiple target rules" don't do what I thought they do.
> While dealing with this, I think I've found a bug, either in code or in
> documentation. Plus I have a related suggestion for the doc.
>
>
> 1. multi target with "&:" ran twice
>
> Attached is a minimal test case. When run with -j2, it executes the "foo1
> foo2" rule twice, in parallel.

Please verify that you're using a version of GNU make that's new
enough to support this functionality.  It was added in version 4.3 and
the behavior was tweaked slightly in 4.4.

On a system I have with version 4.4, I see the expected behavior with
your supplied makefile:

$ make -j2
date > foo1
sleep 1
date > foo2
cat foo1 foo2 > bar1
cat foo1 foo2 > bar2
$

If you believe you have a new enough version, please include the
output of "make --version" and information about your OS/distribution.


Philip Guenther