cmake: reducing unnecessary rebuilds

[Brad King]

David Faure wrote:
> On Tuesday 21 March 2006 19:55, David Faure wrote:
> 
>>>VERBOSE=1 make
>>
>>Works much better. Thanks!
> 
> .. at least for .h changes triggering .o rebuilds.
> It doesn't tell anything about "libfoo.so has changed so I need to rebuild libbar.so and mybinary which depend on it".

The dependency scanning is dealing only with implicit dependencies. 
This is specific to the Makefile generators because it substitutes for 
the native build tool's lack of implicit dependency scanning.

Explicit dependencies like the one you mention are directly handled by 
make or Visual Studio or Xcode or whatever the native build tool may be.

-Brad