[CMake] Depending on a Config File (CMake and VC++)

[Steve Johns]

> There was a typo in my example: it should not have the comma between the 
> arguments.  The trailing comma is being considered part of the file name!

Great eye, Brad!

So, here what I have now:

IF(CMAKE_CONFIGURATION_TYPES)
   # Handle multi-configuration generators.
   FOREACH(config ${CMAKE_CONFIGURATION_TYPES})
     CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/traps_config.txt
                    ${CMAKE_CURRENT_BINARY_DIR}/${config}/traps_config.txt 
COPYONLY)
   ENDFOREACH(config)
ELSE(CMAKE_CONFIGURATION_TYPES)
   # Handle single-configuration generators.
   CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/traps_config.txt
                  ${CMAKE_CURRENT_BINARY_DIR}/traps_config.txt COPYONLY)
ENDIF(CMAKE_CONFIGURATION_TYPES)


and here is what happens:

-- Configuring done
-- Generating done
CMake Error: Unknown Target referenced : traps_config.txt
CMake Error: Target: traps depends on unknown target: traps_config.txt


this happens with both in-source and out-of-source builds.

> Be careful with this.  For an in-source build this may not work.  That is 
> why my original example included a ".in" extension on the input file.

I don't really understand that part but I did try this, as an experiment

IF(CMAKE_CONFIGURATION_TYPES)
   # Handle multi-configuration generators.
   FOREACH(config ${CMAKE_CONFIGURATION_TYPES})
     CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/traps_config.in
                   ${CMAKE_CURRENT_BINARY_DIR}/${config}/traps_config.txt 
COPYONLY)
   ENDFOREACH(config)
ELSE(CMAKE_CONFIGURATION_TYPES)
   # Handle single-configuration generators.
   CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/traps_config.in
                ${CMAKE_CURRENT_BINARY_DIR}/traps_config.txt COPYONLY)
ENDIF(CMAKE_CONFIGURATION_TYPES)

with identical, failed results.

As I read the docs, we've asked the system to copy a file.  The file is 
there.  I'm at a loss to see
why it doesn't just happen.   Obviously, I have something more to learn here 
...