[cmake-developers] ExternalProject update target dependencies

[Daniele E. Domenichelli]

Hello all,

I have another issue with ExternalProject.

If I add 2 external projects (A and B), with B DEPENDS=A, and
STEP_TARGETS=update, I expect to be able to update B without updating,
building and installing A, since just updating the code is obviously not
dependent.

I tried to look at ExternalProject.cmake, and the code seems to handle
this exactly as I expect, setting the dependency only for the configure
command.

* update depends on download
* download depends on gitinfo.txt and mkdir
* mkdir depends on nothing
* gitinfo.txt is generated by configure_file

Unfortunately, for some reason that I cannot understand, it does not
work as expected, and if I run make B-update, A is built before B update.

You can reproduce this issue with this small test:
https://github.com/drdanz/ep_test


Any idea about the reason why this happens and how to fix this?


Cheers,
 Daniele