[CMake] Problem piping 'execute_process' output

[Brad King]

On 04/29/2011 05:46 AM, J.S. van Bethlehem wrote:
> Am I trying do something that is not possible (I think not, given that 
> the manual explicitly states that OUTPUT_* and ERROR_* may be the same 
> and that results will be merged)

It is not possible to do with *_FILE right now simply because support
was never implemented for it.  The explicit statement about merging
is for *_VARIABLE: "If the same variable is named for both...".

In order to fix this, one would need to modify use of the function
kwsysProcessSetupOutputPipeFile in Source/kwsys/Process(Win32|UNIX).c
to open all needed files ahead of time and then assign the handles
or descriptors at the places the function is called now.  I'll be
happy to review a patch if anyone wants to work on it.

-Brad