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Re: Are prerequisites made in deterministic order when parallelism is di

From: Edward Welbourne
Subject: Re: Are prerequisites made in deterministic order when parallelism is disabled?
Date: Wed, 14 Jun 2017 07:00:05 +0000

Brett Stahlman (13 June 2017 17:33)
> I don't see anything in the Make docs that guarantees prerequisites
> will be processed in left to right order. Opinions on the web seems to
> be split into 2 camps:
> 1. Make always builds dependencies in left to right order, but a
>    well-designed Makefile won't rely upon it.
> 2. Make is free to build dependencies in any order it likes, provided
>    it respects the stated dependencies.
> My own recent experience suggests #2 is the correct statement, but I
> can't rule out the possibility that a bug in my Makefile is producing
> the apparent non-determinism I'm observing. At any rate, can anyone
> point me to a definitive source on this?

I suspect most implementations of make do in fact build in left-to-right
order but none guarantee it; and I won't be surprised if GNU make used
to but has lately stopped doing so, although I can't give you a
definitive source either way.  I certainly wouldn't ever assume
deterministic build order; if one prerequisite needs to be built before
another, the make-file should express that via a dependency (perhaps
just an order-only one).


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