[CMake] set environment variable scope

[Bill Hoffman]

Kaleb Pederson wrote:
> What's the best way to set an environment variable that will be active for a 
> custom target or command?
> 
> For example:
> 
> SET(ENV{TESTING} "MyValueHere")
> MESSAGE(STATUS "Set value to: $ENV{TESTING}")
> ADD_CUSTOM_TARGET(
>         target
>         COMMAND cmdThatRequiresTestingEnvVar
>         VERBATIM
>         )
> 
> Thanks for the help.
> 

There is currently not a direct way to do this.  You would have to 
create a cmake -P script and call the set(ENV in there.  The issue is 
cmake time vs build time.  When that custom command gets run, the cmake 
process is long gone.

-Bill