[CMake] Still problems with add_custom_command

[Martin Kupke]

Hi,

in my CMake project I have the need for a custom command that should be 
processed in case a file is touched...that is the file the custom 
command depends on. I already use the add_custom_command and 
add_custom_target CMake instructions in my project, but always for 
CMakeLists.txt files in subfolders where a static library will be build.

I think I have a real simple requirement, but I don't get it work up to now.
In my main project  I have a subfolder with an own CMakeLists.txt file, 
this subfolder is added to the main project by instruction 
add_subdirectory( "${CMAKE_CURRENT_SOURCE_DIR}/subfolder" ).
Within the CMakeLists.txt in the subfolder I want to call a custom 
command, so I added the following lines:
message( "My Tool started by custom command / target" )
add_custom_command( OUTPUT Out.txt
                     COMMAND tool.exe ${ToolConfig}
                     DEPENDS ${ToolConfig} )
add_custom_target( TOOL_CFG_OUT
                    DEPENDS Out.txt )

In my main project I added the custom target as dependency in the way:
add_dependencies( ${PROJECT_NAME} TOOL_CFG_OUT )

If I start the CMake process generating the Makefile I see the output of 
my message "My Tool started by custom command / target", but the custom 
command is never called.
I would like to have a build configuration that every time the dependend 
file which is declared in the variable ${ToolConfig} is touched, the 
command tool.exe is started.

What am I doing wrong? Do you have a sample for me how to start a custom 
command every time a file is touched. I don't get it work.

Thanks in advance,
Martin...