[CMake] add_custom_command vs add_subdirectory

[Mathieu Malaterre]

Hi,

  I am trying to find a solution with add_custom_command that can only
depends on file generated within the same directory as where it is
defined. What would I need to change here to make this small example
work:

$ cat CMakeLists.txt
project(d12)
cmake_minimum_required(VERSION 2.8)

add_custom_command(
  OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/bla.txt
  COMMAND touch ${CMAKE_CURRENT_BINARY_DIR}/bla.txt
  DEPENDS ${d12_BINARY_DIR}/sub/foo.txt
  )
add_custom_target(bla ALL
  DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/bla.txt
  )
add_subdirectory(sub)

and

$ cat sub/CMakeLists.txt
add_custom_command(
  OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/foo.txt
  COMMAND touch ${CMAKE_CURRENT_BINARY_DIR}/foo.txt
  )


Ref:
svn co https://gdcm.svn.sourceforge.net/svnroot/gdcm/Sandbox/CMakeBug/12

Thanks for suggestions,
-- 
Mathieu