[CMake] [CMake 0012322]: Ability to add source files to target created with ExternalProject

[David Cole]

The typical ExternalProject is a bit of a black-box to the containing
project, and a list of sources is something most users will not
have... That's another reason why I am skeptical as to the usefulness
of this feature to the general ExternalProject consumer.


On Fri, Aug 12, 2011 at 11:24 AM, Yuri Timenkov <yuri at timenkov.ru> wrote:
> Ok, I'll double-check this next monday. That's why I was confused.
>
> On the second thought if you have a list of sources you can add them as
> dependencies in addition to build rule, then step will be re-run as
> expected. May be it's my case.
>
> Anyways I need to do some more investigation.
>
> Best wishes,
> Yuri
>
> On Aug 12, 2011 6:54 PM, "David Cole" <david.cole at kitware.com> wrote:
>> You can re-open the issue if you would like to have more discussion there.
>>
>> The build step does not always re-run. If you have an "update" step
>> before the build step, then the update step always re-runs, and the
>> build step after it, but many external projects do not have an update
>> step, or anything else that "always" forces a build when there's a
>> "Build Solution" executed on the containing project. (If it does, then
>> that's a bug, because it's only supposed to re-execute steps that
>> *need* to be re-executed.)
>>
>>
>> Thanks,
>> David
>>
>>
>> On Fri, Aug 12, 2011 at 10:46 AM, Yuri Timenkov <yuri at timenkov.ru> wrote:
>>> Hello David,
>>> It seems that I can't add notes to closed bug, so I ask you directly.
>>> I don't quite understand what kind of automatic dependencies you're
>>> talking
>>> about.
>>> If I change file in this way and do "build solution" cmake will
>>> automatically launch build for external project. IIRC it always executes
>>> build when I build solution.
>>> As I said, for my local purposes I can use modified ExternalProject.cmake
>>> file, but I thought such feature might be useful for others.
>>>
>>> On Fri, Aug 12, 2011 at 5:24 PM, Mantis Bug Tracker
>>> <mantis at public.kitware.com> wrote:
>>>>
>>>> A NOTE has been added to this issue.
>>>> ======================================================================
>>>> http://public.kitware.com/Bug/view.php?id=12322
>>>> ======================================================================
>>>> Reported By:                Yuri
>>>> Assigned To:                David Cole
>>>> ======================================================================
>>>> Project:                    CMake
>>>> Issue ID:                   12322
>>>> Category:                   CMake
>>>> Reproducibility:            always
>>>> Severity:                   tweak
>>>> Priority:                   normal
>>>> Status:                     resolved
>>>> Resolution:                 won't fix
>>>> Fixed in Version:           CMake 2.8.6
>>>> ======================================================================
>>>> Date Submitted:             2011-07-08 05:27 EDT
>>>> Last Modified:              2011-08-12 09:24 EDT
>>>> ======================================================================
>>>> Summary:                    Ability to add source files to target
>>>> created
>>>> with
>>>> ExternalProject
>>>> Description:
>>>> In my scenario I have part of project which should be built with
>>>> different
>>>> toolset (Main project is built with VC2010, and some legacy libraries
>>>> with
>>>> VC6
>>>> and VS2005).
>>>> Basically nested project contains
>>>> set(Proj_SRCS src1.cpp src2.cpp...)
>>>> add_library(Proj MODULE ${Proj_SRCS})
>>>>
>>>> So set() command may be moved into separate file which in turn could be
>>>> included
>>>> into main project. So I want to see them there to edit in IDE, but not
>>>> compile.
>>>>
>>>> The only possibility to add files to custom target - is specify SOURCES
>>>> in
>>>> add_custom_target command (It's impossible to call cmTarget::AddSources
>>>> from
>>>> outside). However, ExternalProject_Add macro doesn't add any sources.
>>>>
>>>> Moreover, there is a kind of chicken-and-egg problem: all arguments are
>>>> parsed
>>>> and set as property on target. But you can't set property while there is
>>>> no
>>>> target.
>>>>
>>>> So as quick work-around I made private copy of ExternalProject.cmake and
>>>> pass
>>>> sources as directory property.
>>>>
>>>> So I'm asking for ideas how to properly implement this feature: modify
>>>> somehow
>>>> parameters parsing in ExternalProject, or may be introduce command which
>>>> allows
>>>> adding new sources to existing targets (I'm not sure if this will work,
>>>> but for
>>>> me it sounds like target_link_libraries command).
>>>> ======================================================================
>>>>
>>>> ----------------------------------------------------------------------
>>>>  (0027196) David Cole (manager) - 2011-08-12 09:23
>>>>  http://public.kitware.com/Bug/view.php?id=12322#c27196
>>>> ----------------------------------------------------------------------
>>>> I don't think we should do this.
>>>>
>>>> If we allow source files from external projects to be added directly to
>>>> the IDE
>>>> representations of the external projects in the containing project, then
>>>> people
>>>> will expect the dependencies to work correctly automatically...
>>>>
>>>> The dependencies will not work automatically. You will have to
>>>> forcefully
>>>> trigger an incremental rebuild of the external project on *any* build of
>>>> the
>>>> containing project, and then hope that its build system appropriately
>>>> picks up
>>>> only the incremental build changes necessary.
>>>>
>>>> I view this as fragile, and would not like to see it go in CMake unless
>>>> it
>>>> can
>>>> be made robust, and shown to work automatically and as developers would
>>>> expect
>>>> in the vast majority of use cases.
>>>>
>>>> ----------------------------------------------------------------------
>>>>  (0027197) David Cole (manager) - 2011-08-12 09:24
>>>>  http://public.kitware.com/Bug/view.php?id=12322#c27197
>>>> ----------------------------------------------------------------------
>>>> If you need more help on this issue/topic, please send email to the
>>>> CMake
>>>> users
>>>> list asking for advice there. There's a much wider readership of the
>>>> mailing
>>>> list than there is of the bug database.
>>>>
>>>> Issue History
>>>> Date Modified    Username       Field                    Change
>>>> ======================================================================
>>>> 2011-07-08 05:27 Yuri           New Issue
>>>> 2011-08-12 09:19 David Cole     Assigned To               => David Cole
>>>> 2011-08-12 09:19 David Cole     Status                   new => assigned
>>>> 2011-08-12 09:23 David Cole     Note Added: 0027196
>>>> 2011-08-12 09:23 David Cole     Status                   assigned =>
>>>> resolved
>>>> 2011-08-12 09:23 David Cole     Fixed in Version          => CMake 2.8.6
>>>> 2011-08-12 09:23 David Cole     Resolution               open => won't
>>>> fix
>>>> 2011-08-12 09:24 David Cole     Note Added: 0027197
>>>> ======================================================================
>>>>
>>>
>>>
>