[CMake] Interference between siblings

[Weiguang Guan]

Hi CMake users,

Variables, include paths, library paths, etc. are inherited from top-level 
directory to subdirectories. If we follow this philosophy sibling 
directories shouldn't affect one another. However, I find this is not the 
case. 

I have a source tree, which looks like

src 
    / libraries 
		/ vtk
		/ itk
		/ ...
    / apps	
		/ app1 
		/ app2

where CMakeLists.txt in a non-leaf directory contains nothing but 
SUBDIRS(...). Then I create a directory 'build' to be the root of build 
tree. In the build directory I ccmake ....../src, then the build tree is 
generated, which looks like

build
    / libraries
                / vtk
                / itk
                / ...
    / apps
                / app1
                / app2

Take the Makefile for app1 as an example. It is different from the 
Makefile generated by using ccmake ....../src/apps/app1.
 
Weiguang

-- 
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Weiguang Guan, Research Engineer
RHPCS, McMaster University
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