[cmake-developers] [PATCH] ExternalProject_Add: Allow generator expressions in CMAKE_CACHE_ARGS

[David Cole]

Great -- thanks for checking. This proposed change looks reasonable to me...

On Fri, Apr 17, 2015 at 12:27 PM, Andrey Pokrovskiy
<wonder.mice at gmail.com> wrote:
>> does the external project's configure step re-run when you edit only the CMAKE_CACHE_ARGS for it?
>
> Yes. Verified with the following example:
>
> ----
> cmake_minimum_required(VERSION 3.2)
>
> project(CMakeExternalProjectGenExpr)
>
> include(ExternalProject)
>
> set(ZF_QUEUE_INSTALL_PREFIX "${CMAKE_CURRENT_BINARY_DIR}/zf_queue.install")
>
> ExternalProject_Add(zf_queue_ep
>     GIT_REPOSITORY https://github.com/wonder-mice/zf_queue.git
>     UPDATE_COMMAND ""
>     INSTALL_DIR ${ZF_QUEUE_INSTALL_PREFIX}
>     CMAKE_CACHE_ARGS
>         -DCMAKE_INSTALL_PREFIX:string=<INSTALL_DIR>)
>
> On Fri, Apr 17, 2015 at 4:19 AM, David Cole <DLRdave at aol.com> wrote:
>> With this change, does the external project's configure step re-run
>> when you edit only the CMAKE_CACHE_ARGS for it?
>>
>> (It did with the *.in / configure_file approach...)
>>
>>
>> On Fri, Apr 17, 2015 at 12:55 AM, Andrey Pokrovskiy
>> <wonder.mice at gmail.com> wrote:
>>> In current implementation of ExternalProject_Add generator expressions
>>> are supported in CMAKE_ARGS (probably by coincidence), but not in
>>> CMAKE_CACHE_ARGS. This patch will enable generators expressions in
>>> CMAKE_CACHE_ARGS.
>>>
>>> Use case:
>>> set(LIBEV_LIBRARIES $<TARGET_FILE:ev>)
>>> ExternalProject_Add(
>>>     ...
>>>     CMAKE_CACHE_ARGS
>>>          -DLIBEV_LIBRARIES=${LIBEV_LIBRARIES}
>>>     ...)
>>>
>>> ---
>>>  Modules/ExternalProject.cmake | 5 +----
>>>  1 file changed, 1 insertion(+), 4 deletions(-)
>>>
>>> diff --git a/Modules/ExternalProject.cmake b/Modules/ExternalProject.cmake
>>> index 0c73d41..1c7cf51 100644
>>> --- a/Modules/ExternalProject.cmake
>>> +++ b/Modules/ExternalProject.cmake
>>> @@ -1126,10 +1126,7 @@ function(_ep_write_initial_cache target_name
>>> script_filename script_initial_cach
>>>    # Replace location tags.
>>>    _ep_replace_location_tags(${target_name} script_initial_cache)
>>>    # Write out the initial cache file to the location specified.
>>> -  if(NOT EXISTS "${script_filename}.in")
>>> -    file(WRITE "${script_filename}.in" "\@script_initial_cache\@\n")
>>> -  endif()
>>> -  configure_file("${script_filename}.in" "${script_filename}")
>>> +  file(GENERATE OUTPUT "${script_filename}" CONTENT "${script_initial_cache}")
>>>  endfunction()
>>>
>>>
>>> --
>>> 2.3.2 (Apple Git-55)
>>>
>>> --
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