[oe] [OE-core] [RFC][PATCH] cmake: respect ${S} and ${B}

[Martin Jansa]

On Thu, Dec 05, 2013 at 12:38:57AM +0000, Ross Burton wrote:
> Hi,
> 
> This is a Request For Comments because it changes behaviour of the cmake class
> and I'm not entirely knowledgeable in cmake.

Neither am I, but patch looks reasonable and I like it, because I was
planing to do something similar.

> For some reason, cmake.bbclass doesn't use ${S} and ${B}, but instead has it's
> own variables OECMAKE_SOURCEPATH ("." by default) and OECMAKE_BUILDPATH ("" by
> default).  Those defaults meant that the build happened in the source directory,
> which conveniently was ${S}.  Unless ${B} was also set, in which case it all
> broke.
> 
> I don't see a good reason for cmake.bbclass having it's own special versions of
> ${S} and ${B}, so this patch drops them and replicates some of the logic in
> autotools.bbclass: specifically the part where if ${S} and ${B} are different,
> delete ${B} before building.  This ensures that switching machine doesn't re-use
> the same build directory, which was the cause of me going back to look at this
> (libproxy trying to use the nuc sysroot when I'm building for qemux86-64).
> 
> Some open questions:
> 
> 1) As I understand it cmake has more reliable support for out-of-tree builds
> than autotools.  If this is the case should cmake.bbclass set B ?=
> "${WORKDIR}/build", or leave setting of B to separatebuilddir.inc?  Are there
> known recipes using cmake that fail with out-of-tree builds?
> 
> 2) Is dropping OECMAKE_SOURCEPATH and OECMAKE_BUILDPATH acceptable?  Nothing in
> oe-core uses them and there's three (IIRC) recipes in meta-oe that use them.
> Assuming the answer to (1) is "separatebuilddir.inc" then the only fallout
> should be these recipes using in-tree builds until OECMAKE_BUILDPATH is replaced
> with B.
> 
> Feedback and testing from people who actively use cmake very welcome.
> 
> Cheers,
> Ross
> _______________________________________________
> Openembedded-core mailing list
> Openembedded-core at lists.openembedded.org
> http://lists.openembedded.org/mailman/listinfo/openembedded-core

-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa at gmail.com
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