[CMake] Generated file and parallel build.

[Óscar Fuentes]

Several libraries depends on a generared header file. For enabling
parallel builds I need to state that dependency, and I do it with
set_source_files_properties. This happens inside a macro:

macro(add_llvm_library name)
  if( LLVM_SOURCE_COMMON_DEPENDS )
    set_source_files_properties( ${ARGN}
      PROPERTIES OBJECT_DEPENDS ${LLVM_SOURCE_COMMON_DEPENDS}
      )
  endif( LLVM_SOURCE_COMMON_DEPENDS )
  add_library( ${name} ${ARGN} )
....

where LLVM_SOURCE_COMMON_DEPENDS contains the name of the custom target
that is used to trigger the custom command that generates the file:

add_custom_command(OUTPUT ${path_to_intrinsics_gen}
  COMMAND tblgen -gen-intrinsic ... -o ${path_to_intrinsics_gen}
  DEPENDS tblgen
  COMMENT "Building intrinsics.gen...")

add_custom_target(intrinsics_gen ALL
  DEPENDS ${path_to_intrinsics_gen})

set(LLVM_SOURCE_COMMON_DEPENDS ${LLVM_SOURCE_COMMON_DEPENDS} intrinsics_gen )

This doesn't work. The parallel build tries to compile the sources
that depends on intrinsics_gen before executing the custom command. I've
tried to use ${path_to_intrinsics_gen} (that is, the custom command
output) instead of intrinsics_gen, to no avail.

What I'm doing wrong?

CMake 2.6.1 -G "Unix Makefiles".

-- 
Oscar