[LLVMdev] [cfe-dev] Testing and CMake

[Cédric Venet]

>
> Is it true that CMake only generates absolute paths? Any idea on the  
> difficulty of generating relative paths? I consider this a pretty big  
> obstacle...
>   

It is probably impossible, by design:

 From the CMake FAQ: http://www.cmake.org/Wiki/CMake_FAQ

Why does CMake use full paths, or can I copy my build tree?

CMake uses full paths because:
- configured header files may have full paths in them, and moving those 
files without re-configuring would cause upredictable behavior.
- because cmake supports out of source builds, if custom commands used 
relative paths to the source tree, they would not work when they are run 
in the build tree because the current directory would be incorrect.
- on Unix systems rpaths might be built into executables so they can 
find shared libraries at run time. If the build tree is moved old 
executables may use the old shared libraries, and not the new ones.

Can the build tree be copied or moved?
The short answer is NO. The reason is because full paths are used in 
CMake, see above. The main problem is that cmake would need to detect 
when the binary tree has been moved and rerun. Often when people want to 
move a binary tree it is so that they can distribute it to other users 
who may not have cmake in which case this would not work even if cmake 
would detect the move.
The workaround is to create a new build tree without copying or moving 
the old one.