Re: add Order-only Prerequisites example

[Paul Smith]

On Sun, 2012-07-08 at 06:04 +0800, address@hidden wrote:
> Can you please add at least _one_ example to
> (info "(make) Prerequisite Types")
> also consider retitling it "Order-only Prerequisites" or adding a sub-section.
> 
> Does it mean the only difference between
> A:B C;D
> A:|B C;D
> is that C might be run first in the former?

No.  C will never be run first, before B.  If you enable parallel builds
then B and C might be run at the same time (but B will still be started
first, then C).

In the first example, first B and C will be rebuilt then A will be
rebuilt if either A doesn't exist, OR B or C are newer than A.

In the second example, first B and C will be rebuilt then A will be
rebuilt if A doesn't exist, period.  Since B and C are related to A by
build order ONLY, they are built first BUT they don't play a role in
deciding if A should be rebuilt.