[CMake] Dependency rule not included

[Michael Wild]

On 12/08/2010 04:28 PM, Vivien Delmon wrote:
> On 12/08/2010 04:13 PM, Michael Wild wrote:
>> On 12/08/2010 03:54 PM, Micha Renner wrote:
>>> Am Mittwoch, den 08.12.2010, 14:55 +0100 schrieb Vivien Delmon:
>>>> CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
>>>> ADD_CUSTOM_COMMAND(OUTPUT toto.h toto.c
>>>>      COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/create_totoc_totoh.sh
>>>> )
>>> SET_SOURCE_FILES_PROPERTIES(toto.h toto.c PROPERTIES GENERATETED TRUE)
>>>
>>> See:
>>> http://www.cmake.org/cmake/help/cmake-2-8-docs.html#command:set_source_files_properties
>>>
>>> and:
>>> http://www.cmake.org/cmake/help/cmake-2-8-docs.html#prop_sf:GENERATED
>>>
>>>
>>>> INCLUDE_DIRECTORIES(${CMAKE_CURRENT_BINARY_DIR})
>>>> ADD_LIBRARY(titi toto.c)
>>>> ADD_LIBRARY(tata tata.c)
>>>
>>> Greetings
>>> Micha
>>>
>>
>>
>> the GENERATED property is set automatically by ADD_CUSTOM_COMMAND. But I
>> suspect the problem is that you used a relative path in your OUTPUT
>> option. *Always* specify full paths in the OUTPUT and DEPENDS options.
>> Also, make the custom command DEPENDS on the create_totoc_totoh.sh
>> script and it's input (perhaps it reads some configuration file or you
>> pass it another file as an argument, etc.).
> 
> Both solutions does not solve the problem.
> 
> CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
> ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/toto.h
> ${CMAKE_CURRENT_SOURCE_DIR}/toto.c
>     COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/create_totoc_totoh.sh
> )
> SET_SOURCE_FILES_PROPERTIES(toto.h toto.c PROPERTIES GENERATETED TRUE)
> INCLUDE_DIRECTORIES(${CMAKE_CURRENT_BINARY_DIR})
> ADD_LIBRARY(titi toto.c)
> ADD_LIBRARY(tata tata.c)
> 
> The problem is that tata.c include toto.h. cmake does not know it
> because C file dependencies are constructed later by make. The result is
> that CMakeFiles/tata.dir/build.make does not include the rule needed to
> construct toto.h. I try to find a way to add this rule.
> A workaround consists in putting toto.h in libtata dependencies but it's
> not a dependency of libtata but a dependency of tata.c.
> 
> The error is :
> [ 33%] Building C object CMakeFiles/tata.dir/tata.c.o
> /home/vivien/tmp/cmake_deps/tata.c:1:18: fatal error: toto.h: No such
> file or directory
> compilation terminated.
> 

Ah, yes. I missed the "tata"<->"toto" difference ;-) In this case you
can use

set_source_files_properties(tata.c PROPERTIES
  OBJECT_DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/toto.h)

Which is, of course, less than ideal because you have to know which
sources include toto.h. *BUT*: Actually, since tata.h is including
toto.h, it is likely that the tata library actually needs to be linked
against the titi library, so adding

TARGET_LINK_LIBRARIES(tata titi)

also solves the problem, but in a much cleaner way.

Another thin: *never* generate output in the source tree. Actually, I
start to think that the ADD_CUSTOM_COMMAND should error out if any of
the OUTPUT files is located in the source tree for out-of-source
builds... At least, it should print a big fat "developer-warning".

Michael