On 01/03/2013 11:11 AM, Paul Smith wrote:
On Thu, 2013-01-03 at 05:53 -0800, Jamie Cuesta wrote:
http://blog.melski.net/2013/01/01/pragma-multi-and-rules-with-multiple-outputs-in-gnu-make/
describes a (IMHO very significant, perhaps even "gaping") limitation of GNU
make (and offers a (IMHO) clean/elegant solution to same).
http://lists.gnu.org/archive/html/make-alpha/2002-12/msg00000.html
There may have been other similar threads since, I can't remember.
I'm not so thrilled about the idea of having a #pragma concept that
changes the way normal rules are interpreted.
We chose the #pragma syntax for two reasons. First, it entirely avoids
the debate about what syntax to use to indicate multiple output targets.
From the linked thread that seems to have been a point of some
contention, and there's disagreement between different make variants --
some use "a + b", some use "[a b]", somebody proposed using something
like "a b |:" or similar. All of the alternatives have drawbacks,
albeit perhaps not anything that would actually impact users in practice
(eg, what if you actually want to have a target named "+"?).
The second advantage of #pragma syntax is that it is not
backwards-incompatible. A makefile using "#pragma multi" will still be
usable with older versions of GNU make, except that you don't get the
special multi-output behavior. In the best case, the alternatives will
cause older versions of GNU make to emit spurious warnings; in the worst
case they could cause build failures. "#pragma multi" is completely
invisible to versions of GNU make that don't support it.
Best regards,
Eric Melski
Chief Architect
Electric Cloud, Inc.
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