[oe] [meta-oe] opencv picks up eigen3 headers from host include

[Lukas Bulwahn]

Hi everyone,

Working on the meta-ros layer [1] and more specifically bitbaking 
cv-bridge [2], I stepped into an issue with opencv.

When I execute `bitbake opencv` with versions

meta              = "master:bc6258f88705b0e7989089a8666ac5e5d2355823"
meta-oe           = "master:6b50a7d6621eba239380b11606110caab814eb51"

bitbake emits this warning:

WARNING: QA Issue: opencv: The compile log indicates that host include 
and/or library paths were used.
          Please check the log 
'/home/lukas/oe-core/build/tmp-eglibc/work/x86_64-oe-linux/opencv/2.4.3-r2/temp/log.do_compile' 
for more information.


In log.do_compile, the g++ calls have the parameter "-isystem 
/usr/include/eigen3". I have installed libeigen3-dev 3.0.5-1 on my 
ubuntu host machine and bitbake opencv seems to pick up the eigen3 
headers from the host include. To repair this issue, I see two 
alternatives here:

- either add eigen3 as recipe to meta-oe and add eigen3 as a dependency. 
Kartik Mohta provides recipes for eigen at his repository [3] and I have 
some older copy at our repository [4].
- or ensure that opencv does not use eigen3 at all and hence does not 
pick up the eigen3 headers from the host machine.

What are your thoughts?

Lukas

[1] https://github.com/bmwcarit/meta-ros
[2] 
https://github.com/bulwahn/meta-ros/commit/cc0ce9c4c3c49fc72eb95712a629350bc9c6a21a
[3] 
https://github.com/kartikmohta/meta-km/tree/master/recipes-extended/eigen
[4] https://github.com/bmwcarit/meta-ros/tree/master/recipes-extended/eigen