[CMake] qt .qrc file modifications require two builds

[Brad King]

Clinton Stimpson wrote:
> If I specify the input (path to test.h.in) & output (path to generated 
> test.h) for the "CMake Rules" build phase, the problem goes away.
> Maybe we can put all inputs and all outputs in there for generated files 
> in that project?  The script (makefile) it calls already has the smarts 
> for which ones really need updating.

I once investigated doing this but never finished.  I think it requires
a graph algorithm to split rules into maximal groups such that each
group has inputs and outputs that are disjoint.  Each group gets one
"Run Script" build phase.

> Or is there a reason we can't just add a build phase for each 
> add_custom_command() ?  Possibly too much clutter?

One could try that.  I don't know how well build phases scale.
There is also the issue that build phases are not per-configuration,
so the scripts would have to test $(CONFIGURATION).  Currently this
is done by using $(CONFIGURATION) to select which Makefile rule to
drive.

Somewhere I have a patch series that I started last time I investigated
this problem.  If anyone wants to volunteer to work on it I can send my
current patches (they probably don't apply to CVS HEAD now though).
IIRC the patches factor out some of the VS IDE custom script code for
re-use with Xcode.

-Brad