[CMake] Generated source files and dependencies(+) (Wojciech Migda)

[Clinton Stimpson]

Why not include it in the foo target, instead of making a new a_h_gen target 
and doing extra dependencies manually?

-----------------
INCLUDE_DIRECTORIES( ${CMAKE_CURRENT_SOURCE_DIR} )
SET_SOURCE_FILE_PROPERTIES( ${CMAKE_CURRENT_SOURCE_DIR}/a.h PROPERTIES     
   GENERATED TRUE )

ADD_CUSTOM_COMMAND(
  OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/a.h"
  COMMAND echo \"\#define STAMP \\\"\" `date` \"\\\"\"  > a.h
  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/a.txt"
)

ADD_LIBRARY( foo STATIC a.c ${CMAKE_CURRENT_SOURCE_DIR}/a.h)
----------------

Clint

On Tuesday 08 September 2009 01:31:32 pm Wojciech Migda wrote:
> Hi,
>
> some time ago there was a discussion, which has highlighted problem I
> am facing now, but it did not provide final conclusions
> (http://www.cmake.org/pipermail/cmake/2008-September/024093.html).
>
> Take this example:
>
> --------------------------
> INCLUDE_DIRECTORIES( ${CMAKE_CURRENT_SOURCE_DIR} )
>
> SET_SOURCE_FILE_PROPERTIES( ${CMAKE_CURRENT_SOURCE_DIR}/a.h PROPERTIES
> GENERATED TRUE )
>
> ADD_CUSTOM_COMMAND(
>   OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/a.h"
>   COMMAND echo \"\#define STAMP \\\"\" `date` \"\\\"\"  > a.h
>   DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/a.txt"
> )
>
> ADD_CUSTOM_TARGET( a_h_gen DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/a.h )
>
> ADD_LIBRARY( foo STATIC a.c )
> ---------------------------------
>
> Here we have file a.c which includes file a.h.
> a.h is generated, with dependency on a.txt.
>
> What I'd expect from the above (and what ZNV hinted in the 2008
> thread) building foo library should check dependencies of a.c and if
> a.h doesn't exist generate it or it a.txt has changed regenerate a.h
>
> However, files generated with cmake 2.6.4 show that:
>
> 1. in Makefile2 a.c has no dependencies on a.h or a_h_gen
> 2. depend.make for foo library has dependency on a.h only if a.h
> existed at the time of cmake execution or during dependency scanning
> for a.c
>
> The result is that building foo doesn't generate a.h nor a.h is
> refreshed if a.txt changed even though depend.make for foo lists a.h
> as its dependency. If I add the following line at the end:
>
> ADD_DEPENDENCIES( foo a_h_gen )
>
> a dependency for foo on a_h_gen will appear in Makefile2 and
> everything will work as expected.
>
> This however, in a real life example I am working on there are
> hundreds of source files and tens of libraries which indirectly may
> depend on a generated header and thus manual specification of
> dependency between built library and generated file is simply impractical.
>
> Thus, my question is whether I am missing something in my example
> CMakeLists.txt or cmake at this stage is simply unable to handle such
> situation.
>
> In the 2008 discussion ZNV illustrated exactly the same situation by
> the single vs. two-level dependency illustration, and Esben's response
> was that properly constructed CMakeLists.txt file shall enforce single
> level of dependencies. Nonetheless, the example above shows that it is
> not the case.
>
> Any hints allowing me to reach the desired cmake behaviour will be
> appreciated. THANKS.
>
> -Wojciech
>
>
> ----------------------------------------------------------------------
> Wykonaj diagnostyke skory i odbierz swoj Prezent!
> http://link.interia.pl/f22f1
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the CMake FAQ at:
> http://www.cmake.org/Wiki/CMake_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.cmake.org/mailman/listinfo/cmake