[CMake] How to rerun cmake if a file changes

[Vladislav Vaintroub]

Hello,
we use a text file as input for out build to store version info.  The
content of this file is
./VERSION:

MYSQL_VERSION_MAJOR=5
MYSQL_VERSION_MINOR=5
MYSQL_VERSION_PATCH=8
MYSQL_VERSION_EXTRA=

During cmake run, the information is extracted, parsed,
CPACK_PACKAGE_FILE_NAME is generated,  and some other things happen, e.g we
configure a header file mysql_version.h. 
So far, it works nicely, the only problem  with it is that cmake is not
rerun when this file changes. I made an attempt to fix it by introducing
custom command and custom target

ADD_CUSTOM_COMMAND(
   OUTPUT  ${CMAKE_BINARY_DIR}/VERSION.dep
   COMMAND ${CMAKE_COMMAND} ${CMAKE_BINARY_DIR}
   COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_BINARY_DIR}/VERSION.dep
   DEPENDS ${CMAKE_SOURCE_DIR}/VERSION
   )
ADD_CUSTOM_TARGET(check_version ALL DEPENDS ${CMAKE_BINARY_DIR}/VERSION.dep)

This seems to work but is not without problems. For example the very first
build with rerun cmake to generate VERSION.dep.  It takes some seconds with
Makefiles,  this is not a big problem, however in Visual Studio (I'm using
VS2010) the very first build would tell me "N  solutions regenerated, you
want to rebuild?", and then  I clicking "OK" a COM error would popup (the
build would actually still continue run successfully despite popups and COM
error).

So the question is if there is a nicer way to accomplish what I want to do.
I'm aware that if VERSION had CMake syntax with SET(MYSQL_MAJOR_VERSION 5)
etc, then I could just INCLUDE this file, and this would fix  problems I
have.  I'm however more interested in a solution that would not force that
file to be written in CMake syntax. 

Thanks,
Vladislav