[CMake] CMake:question of the time when the command will happen in add_custom_command(...)

[Petr Kmoch]

No, it is indeed compiled and linked just fine. What I meant is:

Without any custom commands, the build process conceptually looks like this:

buildMain() {
  compile_object_files();
  link_main_binary();

  message("Built target main");
}

With a post-build custom command:

buildMain() {
  compile_object_files();
  link_main_binary();
  post_build_command();

  message("Built target main");
}

The custom command becomes a part of the entire process of "Building
target," that's why the "Built target" message appears after the command
runs.

BTW, please keep the mailing list in copy when replying.

Petr

On 22 April 2016 at 10:02, Chaos Zhang <zcsd2012 at gmail.com> wrote:

> So what you mean is the target have not been complied and linked after i introduce
> custom commands into this target right? Do i understand right?
>
> Thanks a lot for your generous help. :-)
>
> 2016-04-22 16:38 GMT+08:00 Petr Kmoch <petr.kmoch at gmail.com>:
>
>> Hi,
>>
>> the reason is that the post-build command is actually a part of building
>> "main the target." Once you introduce custom commands into a target,
>> building it includes them all, and not just compiling the object files and
>> linking the binary. You will notice that the "Linking C exectuable main"
>> line came before the post-build message, so it did happen in the correct
>> order.
>>
>> Petr
>>
>> On 22 April 2016 at 06:25, Chaos Zhang <zcsd2012 at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> I have some trouble when i use PRE_BUILD | PRE_LINK | POST_BUILD in
>>> command
>>> "add_custom_command(...)". When i use POST_BUILD, i found the command
>>> will
>>> execute before target had been built, like this:
>>>
>>> 1 [root at VM_33_35_centos build]# make
>>> 2 Scanning dependencies of target main
>>> 3 [100%] Building C object CMakeFiles/main.dir/main.c.o
>>> 4 Linking C executable main
>>> 5 This is pre build
>>> 6 This is post build
>>> 7 [100%] Built target main
>>>
>>> In my CMakeLists.txt, the content is:
>>>  1 cmake_minimum_required(VERSION 2.8)
>>>  2 add_executable(main main.c)
>>>  3 add_custom_command(TARGET main
>>>  4                     PRE_BUILD
>>>  5                     COMMAND echo "This is pre build "
>>>  6         )
>>>  7 add_custom_command(TARGET main
>>>  8                     POST_BUILD
>>>  9                     COMMAND echo "This is post build"
>>>  10         )
>>>
>>> Why the command echo "This is post build" in 8 line(CMakeLists.txt) did
>>> not
>>> execute after [100%] Built target main in 7 line(Linux command)?
>>>
>>>
>>>
>>>
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