[CMake] add_subdirectory inheritance (patch)

David Cole david.cole at kitware.com
Thu Apr 19 08:56:03 EDT 2012 

If that's the case then "NOINHERIT" is not the correct name for this.
(Because that, to me, primarily implies CMake variable value
inheritance, and directory properties, and everything that inherits.)



On Thu, Apr 19, 2012 at 8:48 AM, irukandji <irukandji at voidptr.eu> wrote:
> What my thought was:
>
> if you are adding the subdirectory, you want to keep what is stored within
> the cmake variables so you can fine grain what to use and not to use in
> subdirectory or pass just some settings from caller, if this would be also
> removed there would be no way to pass anything to subdirectory.
>
> Also the system directories are kept (as they are considered system wide).
> Evertything else is not copyed (void cmMakefile::InitializeFromParent()).
>
> (some code reviewing from your side wouldnt be a bad idea, i have checked
> what is passed and what not using debugger so this should work, there is
> always a possibility i have missed something i am not aware of)
>
> Regards,
> irukandji
>
>
> On 2012-04-19 12:10, David Cole wrote:
>>
>> So, wait. This intends to avoid inheritance of preprocessor, compiler
>> and linker stuff, but it still allows inheritance of all other
>> directory properties and CMake variable values...?
>>
>>
>> On Thu, Apr 19, 2012 at 5:04 AM, irukandji <irukandji at voidptr.eu> wrote:
>>>
>>> Ok, guys, catch... source base is 2.8.7.
>>>
>>> add_subdirectory(source_dir [binary_dir]
>>>                   [EXCLUDE_FROM_ALL] [NOINHERIT])
>>>
>>>
>>> /.../
>>>
>>> If the NOINHERIT argument is provided, the subdirectory build
>>> configuration
>>> will not inherit any preprocessor, compiler or linker specific
>>> parameters.
>>>
>>> Regards,
>>> irukandji
>>>
>>>
>>>
>>> On 2012-04-18 21:07, irukandji wrote:
>>>>
>>>>
>>>> I appreciate the idea but my view is that if the solution (whatever
>>>> dev. solution)
>>>> is not elegant there is something wrong with it.
>>>>
>>>> While testing the posibilities, i had it, i have implemented the
>>>> optional dont_inherit
>>>> flag to add_subdirectory. Tomorrow (some testing first), I'll submit
>>>> a patch, i hope it
>>>> will be accepted as it is completely unintrusive, backward
>>>> compatible, <insert the casual
>>>> buzzwords>,...
>>>>
>>>> Regards,
>>>> irukandji
>>>>
>>>> On 2012-04-18 18:18, Kent Williams wrote:
>>>>>
>>>>>
>>>>> I think I understand what you're trying to do better now.  It's a bit
>>>>> off the beaten path for CMake, and has more moving parts than is
>>>>> strictly necessary.
>>>>>
>>>>> It could be set up as a nested suite of ExternalProjects, and avoid
>>>>> the definitions inheritance issue you're running into.
>>>>>
>>>>> You could also manage this by having a flag that is defined if this is
>>>>> a top-level build and not defined in a standalone build, and using
>>>>> Source Properties to properly set the definitions for the files that
>>>>> need different flags.
>>>>>
>>>>> The problem is that ADD_DEFINITIONS is global for the current project,
>>>>>  It is also -- for that very reason -- if not a deprecated CMake
>>>>> feature, one whose use is discouraged.  You're much better off using
>>>>> SET_SOURCE_FILE_PROPERTIES to handle this kind of configuration trick,
>>>>> since the properties are tied to a particular source file.  You can
>>>>> use macros and FOREACH to avoid having to call
>>>>> SET_SOURCE_FILE_PROPERTIES on every file explicitly.
>>>>>
>>>>> You have become invested in the idea that it can only be done by
>>>>> changing CMake, but you can do it without changing CMake if you get
>>>>> creative with the tools already available to you.
>>>>>
>>>>> On Tue, Apr 17, 2012 at 5:02 PM, irukandji <irukandji at voidptr.eu>
>>>>> wrote:
>>>>>>
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Maybe i can try to reexplain, from head, ignore syntactic errors and
>>>>>> oversimplifying...
>>>>>> **********************************
>>>>>> /sources/cmakelist.txt
>>>>>>
>>>>>> /sources/binaries/helloworld
>>>>>> ..................cmakelists.txt
>>>>>>
>>>>>> /sources/binaries/hellocmake
>>>>>> ..................cmakelists.txt
>>>>>>
>>>>>> /sources/libraries/stdio
>>>>>> ..................cmakelists.txt
>>>>>> ..................description.txt
>>>>>>
>>>>>> /sources/libraries/gfx
>>>>>> ..................cmakelists.txt
>>>>>> ..................description.txt
>>>>>> **********************************
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> helloworld: <<
>>>>>>
>>>>>>
>>>>>>
>>>>>> project(helloworld)
>>>>>> include("${libs}/stdio/description.txt")
>>>>>> include("${libs}/network/description.txt")
>>>>>> file(glob da_files "*.*")
>>>>>> add_executable( helloworld da_files )
>>>>>> helper_add_stdio()
>>>>>> **********************************
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> stdio description <<
>>>>>>
>>>>>>
>>>>>>
>>>>>> function (helper_add_stdio)
>>>>>> include_directory( "${sources}/libraries/stdio" )
>>>>>> target_add_library( ${CMAKE_PROJECT_NAME}
>>>>>> "${BINDIR}/whatever/stdio.lib"
>>>>>> )
>>>>>> add_definition( -DUSING_STDIO )
>>>>>> ...
>>>>>> execute(grab_me_a_beer_and_add_some_more_flags)
>>>>>> ...
>>>>>> if(not exists "${BINDIR}/whatever/stdio.lib")
>>>>>> add_subdirectory( "/sources/libraries/stdio")
>>>>>> endif()
>>>>>> endfunction()
>>>>>> **********************************
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> hellocmake <<
>>>>>>
>>>>>>
>>>>>>
>>>>>> project(hellocmake)
>>>>>> include("${libs}/gfx/description.txt")
>>>>>> include("${libs}/network/description.txt")
>>>>>> file(glob da_files "*.*")
>>>>>> add_executable( hellocmake da_files )
>>>>>> helper_add_gfx()
>>>>>> helper_add_stdio()
>>>>>> **********************************
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> gfx description <<
>>>>>>
>>>>>>
>>>>>>
>>>>>> function (helper_add_gfx)
>>>>>> include_directory( "${sources}/libraries/gfx" )
>>>>>> target_add_library( ${CMAKE_PROJECT_NAME} "${BINDIR}/whatever/gfx.lib"
>>>>>> )
>>>>>> add_definition( -DUSING_GFX )
>>>>>> ...
>>>>>> if(not exists "${BINDIR}/whatever/gfx.lib")
>>>>>> add_subdirectory( "${sources}/libraries/gfx"
>>>>>> "${BINDIR}/whatever/gfx.lib" )
>>>>>> endif()
>>>>>> endfunction()
>>>>>> **********************************
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> sources/cmakelist.txt <<
>>>>>>
>>>>>>
>>>>>>
>>>>>> add_subdirectory( "/sources/binaries/helloworld" )
>>>>>> add_subdirectory( "/sources/binaries/hellocmake" )
>>>>>> **********************************
>>>>>>
>>>>>> * If i run cmake on helloworld, lets say for windows, i get solution
>>>>>> and
>>>>>> vcprojs
>>>>>> of helloworld with dependancy to generated vcproj for stdio. Stand
>>>>>> alone.
>>>>>>
>>>>>> * If i run cmake on hellocmake, lets say for windows, i get solution
>>>>>> and
>>>>>> vcprojs
>>>>>> of hellocmake with dependancy to generated vcproj for stdio and gfx.
>>>>>> Stand
>>>>>> alone.
>>>>>>
>>>>>> * If i run cmake on /sources/cmakelist.txt i get full build.
>>>>>>
>>>>>> * The author(s) of helloworld doesnt need to have a clue about stdio
>>>>>> library
>>>>>> its paths
>>>>>> or whatever as the author(s) of stdio/description.txt has prepared
>>>>>> everything for him
>>>>>> (in a perfect world :) ). Same goes for hellocmake.
>>>>>>
>>>>>> * The full build doesnt need to understand what is behind the
>>>>>> helloworld
>>>>>> and
>>>>>> hellocmake as
>>>>>> they both will take care about building the dependancies on their own.
>>>>>>
>>>>>> * The coupling is minimized.
>>>>>>
>>>>>> * The description.txt can serve as a hook in case of changing whatever
>>>>>> settings for
>>>>>> the libraries (from renaming them, to changing directory tree,
>>>>>> changing
>>>>>> compiler flags etc)
>>>>>>
>>>>>> This is what i would like to achieve. But if you look at >> hellocmake
>>>>>> <<,
>>>>>> the
>>>>>> stdio cmakelists will inherit the include path from gfx library which
>>>>>> you
>>>>>> really
>>>>>> dont want. It will also inherit -DUSING_GFX even if it has nothing to
>>>>>> do
>>>>>> with it.
>>>>>>
>>>>>> Regards,
>>>>>> irukandji
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 2012-04-17 22:56, irukandji wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> I don't know how you'd ever maintain a sane overall project if it
>>>>>>>> depends on each subdirectory having conflicting compiler flags.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Well here is the fun, there is not something like "you", we are
>>>>>>> taling
>>>>>>> about
>>>>>>> over 100 developers and if everyone is handling his own garden, this
>>>>>>> is
>>>>>>> not
>>>>>>> a problem. I cant tell you the details (the lawyers stuff) but
>>>>>>> believe
>>>>>>> me
>>>>>>> it
>>>>>>> is as sane as it can be in regards of doing insane things :)
>>>>>>>
>>>>>>> I'll check your suggestions tomorrow, thank you.
>>>>>>>
>>>>>>> Regards,
>>>>>>> irukandji
>>>>>>>
>>>>>>> On 2012-04-17 20:54, Kent Williams wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> I think then that you shouldn't use add_subdirectory.
>>>>>>>>
>>>>>>>> I'd suggest using the ExternalProject module in this case, because
>>>>>>>> it
>>>>>>>> uncouples the subdirectory's project from the parent project.  In
>>>>>>>> that
>>>>>>>> case, each subdirectory can be its own project and maintain private
>>>>>>>> configurations.
>>>>>>>>
>>>>>>>> You can manage dependencies between ExternalProjects with the
>>>>>>>> DEPENDS
>>>>>>>> keyword.
>>>>>>>>
>>>>>>>> I think that what you're describing doesn't really make any sense to
>>>>>>>> me.  I don't know how you'd ever maintain a sane overall project if
>>>>>>>> it
>>>>>>>> depends on each subdirectory having conflicting compiler flags.
>>>>>>>>
>>>>>>>> Another way you can manage this sort of thing is to use Source file
>>>>>>>> properties -- see SET_SOURCE_FILE_PROPERTIES in the CMake
>>>>>>>> documentation and the "Properties on Source Files" section as well.
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, Apr 17, 2012 at 1:27 PM, irukandji <irukandji at voidptr.eu>
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Oh, hi :)
>>>>>>>>>
>>>>>>>>> Well, the add_subdirectory takes all the preprocessor defines and
>>>>>>>>> include/library
>>>>>>>>> paths defined before calling it into the added "subdirectory"
>>>>>>>>> cmakelists.txt.
>>>>>>>>>
>>>>>>>>> If cmakelists.txt A defines -DWhatever and calls
>>>>>>>>> add_subdirectory(/B)
>>>>>>>>> where
>>>>>>>>> the
>>>>>>>>> cmakelists.txt for building library B resides then the library B is
>>>>>>>>> going to
>>>>>>>>> be
>>>>>>>>> built with -DWhatever. This is probably great behaviour for some
>>>>>>>>> cases
>>>>>>>>> but
>>>>>>>>> can
>>>>>>>>> also be undesired:
>>>>>>>>> in my case, each library has its own description file, residing in
>>>>>>>>> same
>>>>>>>>> directory
>>>>>>>>> as its cmakelists.txt, with only one function, which is included
>>>>>>>>> and
>>>>>>>>> called
>>>>>>>>> with few
>>>>>>>>> parameters to specify runtime etc. by each binary which has a
>>>>>>>>> dependancy
>>>>>>>>> to
>>>>>>>>> library.
>>>>>>>>> The description file function sets the -I to itself for caller, the
>>>>>>>>> -l
>>>>>>>>> to
>>>>>>>>> its output
>>>>>>>>> and, if the output file is not found, also calls add_subdirectory
>>>>>>>>> on
>>>>>>>>> its
>>>>>>>>> own
>>>>>>>>> directory.
>>>>>>>>>
>>>>>>>>> This is a perfect situation for developers as we can just do out of
>>>>>>>>> source
>>>>>>>>> configuration
>>>>>>>>> for whatever directory (where project resides) and only the
>>>>>>>>> dependancy
>>>>>>>>> tree
>>>>>>>>> for that
>>>>>>>>> particular binary is built.
>>>>>>>>>
>>>>>>>>> It also brings additional benefit that the team which takes care
>>>>>>>>> about
>>>>>>>>> specific
>>>>>>>>> library also takes care for description file and needed defines
>>>>>>>>> which
>>>>>>>>> splits
>>>>>>>>> the
>>>>>>>>> ownership of projects and also presents a single point of inclusion
>>>>>>>>> for
>>>>>>>>> that
>>>>>>>>> particular
>>>>>>>>> library, meaning only one file has to be changed for library
>>>>>>>>> specializations.
>>>>>>>>>
>>>>>>>>> For the nightly builds, only executables are added to the build
>>>>>>>>> while
>>>>>>>>> everything
>>>>>>>>> else is built only if actually used.
>>>>>>>>>
>>>>>>>>> It works great, but the add_subdirectory is propagating the
>>>>>>>>> settings
>>>>>>>>> from
>>>>>>>>> executable
>>>>>>>>> to dependant libraries and messes the build.
>>>>>>>>>
>>>>>>>>> The question actually is: can i workaround this behaviour and if
>>>>>>>>> not,
>>>>>>>>> can
>>>>>>>>> you please
>>>>>>>>> include the parameter to add_subdirectory function to NOT propagate
>>>>>>>>> the
>>>>>>>>> settings.
>>>>>>>>>
>>>>>>>>> Regards,
>>>>>>>>> Irukandji
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 2012-04-17 17:58, Kent Williams wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Frankly, I don't entirely understand what the problem is, or what
>>>>>>>>>> your
>>>>>>>>>> proposed solution is.
>>>>>>>>>>
>>>>>>>>>> What is it that you don't want the subdirectory context to
>>>>>>>>>> inherit?
>>>>>>>>>>
>>>>>>>>>> On Tue, Apr 17, 2012 at 10:30 AM, irukandji <irukandji at voidptr.eu>
>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> (as no one answered to my previous email, let me add this:
>>>>>>>>>>> multiplatform
>>>>>>>>>>> project with few million lines
>>>>>>>>>>> of code, sheer size of the project is not allowing to turn around
>>>>>>>>>>> whole
>>>>>>>>>>> directory tree as price / performance
>>>>>>>>>>> is a very relevant factor and even rewriting makefiles/vcprojs to
>>>>>>>>>>> cmake
>>>>>>>>>>> will
>>>>>>>>>>> take months)
>>>>>>>>>>>
>>>>>>>>>>> The add_subdirectory inheritance striked which is practically a
>>>>>>>>>>> show
>>>>>>>>>>> stopper, it was already discussed here
>>>>>>>>>>> http://www.mail-archive.com/cmake@cmake.org/msg34291.html What
>>>>>>>>>>> was
>>>>>>>>>>> proposed
>>>>>>>>>>> (DONT_INHERIT) was a great idea
>>>>>>>>>>> and improvement to versability of CMake and also harmless for
>>>>>>>>>>> backward
>>>>>>>>>>> compatibility so i dont really
>>>>>>>>>>> understand why forcing subproject to inherit all the settings.
>>>>>>>>>>>
>>>>>>>>>>> Yes, what is added with add_subdirectory is not a child but a
>>>>>>>>>>> sibling
>>>>>>>>>>> or
>>>>>>>>>>> even some other part of the tree
>>>>>>>>>>> but the point is that it doesnt stop the cmake from building it
>>>>>>>>>>> correctly
>>>>>>>>>>> but this inheritance is a problem
>>>>>>>>>>> as it adds include directories to wrong versions of headers in
>>>>>>>>>>> public
>>>>>>>>>>> libs
>>>>>>>>>>> (due to bugs in different versions,
>>>>>>>>>>> affecting different platforms,... the unification is impossible),
>>>>>>>>>>> the
>>>>>>>>>>> flags
>>>>>>>>>>> are used on wrong places etc.
>>>>>>>>>>>
>>>>>>>>>>> Is there a way to workaround it?
>>>>>>>>>>>
>>>>>>>>>>> Thank you.
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> 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
>>>>>>>>>>>
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>>>>>>>>>>> http://www.cmake.org/mailman/listinfo/cmake
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>>
>>>>>>>>> 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
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>>
>>>>>>> Powered by www.kitware.com
>>>>>>>
>>>>>>> Visit other Kitware open-source projects at
>>>>>>> http://www.kitware.com/opensource/opensource.html
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>>>>>>> Please keep messages on-topic and check the CMake FAQ at:
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>>>>>>>
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>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>>
>>>>>> 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
>>>>>>
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>>>>
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>>>>
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>>>
>>>
>>>
>>> --
>>>
>>> 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:
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>

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