[CMake] Dependency problem

[pjtr hahn]

2009/6/22 Tyler Roscoe <tyler at cryptio.net>:
> Are you sure it doesn't Just Work if you do it the straightforward way?
Yes I am. I tried all combinations.

If I add the phony_name AND the *.cpp as OUTPUT it will compile on
every run regardless if the .cpp has been touched by the command or
not.
If I only add the phony_name the *.cpp needs a second run to compile.
If I only add the *.cpp my custom command is only run once.



> If it really doesn't, you could try generating your .cpp to somewhere
> out of the way and then do cmake -E copy_if_different to get it to the
> right place. This way, even if your rule updates your .cpp every time,
> it will be only be copied to the place where the compiler looks for it
> if it has changed.
This is what I am actually doing in my script that is run by the
custom command. I leave the *.cpp untouched based on some external
condition even if the rule is executed at every build.
This is what I try to achive. Run the custom command at every build,
check some conditions and based on them update the *.cpp. If the
update condition is met and the file was touched then recompile.

> But really I think it will just work if you add the relevant
> OUTPUT/DEPENDS parameters to your custom commands/targets.
No. OUTPUT definitely doesn't work as expected. Adding the *.cpp to
OUTPUT causes a recompile on every run even if the file was untouched.

Maybe you have some idea on changing other dependency options?