[CMake] Error out on installation when there is already an installation

[John R. Cary]

This is in reference to

iter.cary$ cmake --version
cmake version 2.8.3
iter.cary$ uname -a
Linux iter.txcorp.com 2.6.29.4-167.fc11.x86_64 #1 SMP Wed May 27 
17:27:08 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux


We have a situation where a package needs to be
rebuilt because some dependency is rebuilt.  In
this case, trilinos needs rebuilding because it
depends on openmpi and the version of opempi gets
updated.

Typically, these installations are in a common area,
but by different people.  So one night Joe triggers
a build a trilinos.  Then the next night a new version
of openmpi is available, so Mary triggers a build of
openmpi and then trilinos.

In this situation, Mary's installation of trilinos
fails, because cmake's installation does not overwrite
some files:

-- Installing: 
/usr/local/contrib/trilinos-10.2.0-ser/include/Teuchos_DLLExportMacro.h
-- Up-to-date: 
/usr/local/contrib/trilinos-10.2.0-ser/include/Teuchos_AbstractFactory.hpp
CMake Error at packages/teuchos/src/cmake_install.cmake:54 (FILE):
   file INSTALL cannot set permissions on
   
"/usr/local/contrib/trilinos-10.2.0-ser/include/Teuchos_AbstractFactory.hpp"
Call Stack (most recent call first):
   packages/teuchos/cmake_install.cmake:48 (INCLUDE)
   cmake_install.cmake:41 (INCLUDE)

but then apparently tries to set the permissions anyway.  But
since it did not overwrite, Mary does not own the files, and
so she cannot set the perms.  The result being that the installation
errors out as above, possibly not completing, but at the very
least returning an error code that must be chased down.

It seems to me that one should overinstall, even if the
file is there, if one is going to try to set permissions
afterwards.  Is there a way to force such overinstallation
in cmake?  Or perhaps not error out on a perm change if the
exising perms are okay?

Thx....John Cary