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Re: add Order-only Prerequisites example
From: |
Paul Smith |
Subject: |
Re: add Order-only Prerequisites example |
Date: |
Sun, 08 Jul 2012 11:20:15 -0400 |
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.