[CMake] file dependency not working in external projects

[Eric Doenges]

You're probably missing the BUILD_ALWAYS option to ExternalProject_Add:

|BUILD_ALWAYS <bool>|
    Enabling this option forces the build step to always be run. This
    can be the easiest way to robustly ensure that the external
    project’s own build dependencies are evaluated rather than relying
    on the default success timestamp-based method. This option is not
    normally needed unless developers are expected to modify something
    the external project’s build depends on in a way that is not
    detectable via the step target dependencies (e.g. |SOURCE_DIR| is
    used without a download method and developers might modify the
    sources in |SOURCE_DIR|).

Am 24.09.19 um 15:23 schrieb hex:
> hello,
>
> I have a problem with a build step.
>
> The following command is run every time somefile changes:
>
> add_custom_command( OUTPUT out.put
>     COMMAND touch out.put
>     DEPENDS somefile.txt
> )
>
> add_custom_target( sometarget DEPENDS out.put )
>
>
> I move this snippet inside an external project (with 
> ExternalProject_Add) and the custom command is only run once at build.
>
> I am using absolute path to somefile, the command is not rebuild 
> changing somefile.
>
> I am using Gnu make generator and build with make all
>
>
> What am I missing?
>
-- 

*Dr. Eric Dönges*
Senior Software Engineer

MVTec Software GmbH | Arnulfstr. 205 | 80634 Munich | Germany
doenges at mvtec.com <mailto:mustermann at mvtec.com> | Tel: +49 89 457 695-0 
| www.mvtec.com <http://www.mvtec.com>

Find our privacy policy here <https://www.mvtec.com/imprint>.

Sign up <https://www.mvtec.com/newsletter> for our MVTec Newsletter!

Geschäftsführer: Dr. Wolfgang Eckstein, Dr. Olaf Munkelt
Amtsgericht München HRB 114695

MVTec Software GmbH Logo
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://cmake.org/pipermail/cmake/attachments/20190924/d51785be/attachment-0001.html>