[CMake] custom_command pre_build vs. post_build

[Richard Fuchs]

Ah, I see the note now.  It's not in the section of the cmake book that 
describes the command, but it's in the command index in the back and on 
the web.
So why does it work with the add_custom_target?


Brad King wrote:
> >From the documentation of ADD_CUSTOM_COMMAND:
>
> "Note that the PRE_BUILD option is only supported on Visual Studio 7 or
> later.  For all other generators PRE_BUILD will be treated as PRE_LINK. "
>
> Unfortunately pre-build is impossible (or at least very costly at make
> time) to implement with Makefiles.  There is no way to say "tell me if
> any of these other rules will run and if so then run this rule before
> them otherwise don't run anything".
>
> -Brad
>
>