[CMake] dependency hell with custom commands and multiple outputs

[Michael Wild]

set(srcs ...)
set(output ...)
set(target ...)
set(stamp-file "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/precompile/${target}.stamp)
add_custom_command(
  OUTPUT "${stamp-file}"
  COMMAND command-to-precompile ${srcs}
  COMMAND "${CMAKE_COMMAND}" -E touch "${stamp-file}"
  DEPENDS ${srcs}
  WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
  COMMENT "Precompiling ${target}"
  VERBATIM
  )
set_source_files_properties(${output} PROPERTIES GENERATED TRUE)
set_property(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}" APPEND PROPERTY
    ADDITIONAL_MAKE_CLEAN_FILES ${output})
  

HTH

Michael

On 18. Jan, 2010, at 17:01 , Romain CHANU wrote:

> Michael,
> 
> How do you generate your "sentinel" or "stamp" used by your
> add_custom_command?
> 
> Cheers,
> 
> Romain
> 
> 2010/1/18 Michael Wild <themiwi at gmail.com>
> 
>> Yes, it worked for me.
>> 
>> But, as I already mentioned, be careful to mark the files as GENERATED and
>> add them to the ADDITIONAL_MAKE_CLEAN_FILES directory property. One caveat
>> is, however, that if you delete any of the output files, CMake won't
>> regenerate them unless you also delete the stamp file (or that one is
>> out-of-date).
>> 
>> Also, if your custom output depends on compiler flags, you'll probably want
>> to include ${CMAKE_CFG_INTDIR} in the output-paths to support
>> multi-configuration IDE's. This can be tricky to do if you use wrapper-cmake
>> scripts, because the IDE's expand the variable at build-time and only if
>> they see it on the command line, so you have to make sure it shows up
>> there...
>> 
>> Michael
>> 
>> On 18. Jan, 2010, at 15:56 , Romain CHANU wrote:
>> 
>>> Hi Michael.
>>> 
>>> I got the same situation here. I am using a command which outputs a lot
>> of
>>> files (>100 files).
>>> 
>>> Have you tried what David is suggesting?
>>> 
>>> Thank you to update us.
>>> 
>>> Cheers,
>>> 
>>> 2010/1/13 Michael Wild <themiwi at gmail.com>
>>> 
>>>> Hmmm, thought of something like that myself, but am not sure whether
>>>> dependencies will be handled correctly. Of course, I'll have to label
>> the
>>>> products as GENERATED and add them to  ADDITIONAL_MAKE_CLEAN_FILES. Will
>>>> give it a try...
>>>> 
>>>> 
>>>> Michael
>>>> 
>>>> 
>>>> On 13. Jan, 2010, at 16:17 , David Cole wrote:
>>>> 
>>>>> The best way to deal with this is probably to have a single "sentinel"
>> or
>>>>> "stamp" file that gets generated *every* time the command runs. And
>> then
>>>>> list that file as it's only output that CMake knows about... (But still
>>>> with
>>>>> the full list of inputs.)
>>>>> 
>>>>> Does that work?
>>>>> 
>>>>> 
>>>>> On Wed, Jan 13, 2010 at 8:26 AM, Michael Wild <themiwi at gmail.com>
>> wrote:
>>>>> 
>>>>>> Hi all
>>>>>> 
>>>>>> I just ran into an interesting problem. Say I have a custom command
>> that
>>>>>> produces several files, but only updates them as needed. E.g.
>>>>>> 
>>>>>> add_custom_command(OUTPUT file1.c file2.c file3.c
>>>>>> COMMAND generator file1.inp file2.inp file3.inp
>>>>>> DEPENDS generator file1.inp file2.inp file3.inp
>>>>>> VERBATIM)
>>>>>> 
>>>>>> Now, suppose that file2.inp is changed, the build system will run the
>>>>>> command to update the output. Now, the "generator" program is really
>>>> smart
>>>>>> and only updates file2.c. This causes all hell to break lose (at least
>>>> with
>>>>>> the GNU Makefile generator on OS X), causing the command to run three
>>>> times,
>>>>>> desperately trying to update file1.c and file3.c (because file2.inp is
>>>> newer
>>>>>> than them) and then, as it seems, gives up. The thing repeats with
>> every
>>>>>> invocation of "make".
>>>>>> 
>>>>>> Now, the "generator" requires all the input files to be processed in
>> one
>>>>>> step, so I can't split the command as one would usually do. Also,
>>>> touching
>>>>>> all the output files after calling "generator" isn't really viable
>> since
>>>> I'd
>>>>>> like to prevent unnecessary re-compilation of the produced .c files.
>>>>>> 
>>>>>> 
>>>>>> Are there any good solutions to this problem?
>>>>>> 
>>>>>> 
>>>>>> Michael
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>> 
>>