[CMake] Possible bug: <config>_OUTPUT_NAME not used as target property LOCATION

[Brad King]

Laurentiu Nicolae wrote:
> My project requires the generation of DLLs and executables with
> different postfixes for different configurations. Therefore I am setting
> the <config_OUTPUT_NAME accordingly. However, when I try to add a
> post-build step to the build (as described in the manual), the LOCATION
> property of the target is set to the original generated name, regardless
> of the configuration. I can of course work around this by setting the
> prefixes by hand in the post-build command, but I believe this to be a
> bug. The reason being: if I am using the <config>_OUTPUT_NAME options,
> the LOCATION property becomes rather useless, because it points to
> something that may not be there any more.

Yes, this is a bug.  The LOCATION property was around long before the 
target properties that could affect the name on a per-configuration 
basis.  When those options were added the LOCATION property was never 
updated to deal with them and was left alone to support existing code.

> CMakeLists.txt excerpt:
> 
>     SET_TARGET_PROPERTIES ( ${ProjectName} PROPERTIES DEBUG_OUTPUT_NAME
>          "${ProjectName}D" )
>     SET_TARGET_PROPERTIES ( ${ProjectName} PROPERTIES
> RELWITHDEBINFO_OUTPUT_NAME "${ProjectName}Q" )
>     SET_TARGET_PROPERTIES ( ${ProjectName} PROPERTIES
> RELEASE_OUTPUT_NAME        "${ProjectName}R" )
> 
> 
>   GET_TARGET_PROPERTY ( DllLocation "${ProjectName}" LOCATION )
>   ADD_CUSTOM_COMMAND ( TARGET "${ProjectName}"
>                        POST_BUILD
>                        COMMAND ${CMAKE_COMMAND}
>                        ARGS -E copy "${DllLocation}" "${QOutputPath}"
>                      )

This is a known problem we've been ignoring until someone needed it 
because it is a pain to address.  The problem is that we need to have a 
single value at CMake configure time (the LOCATION) split into multiple 
values at CMake generate time (the per-configuration LOCATION).

One idea we've had is to return a special string for the LOCATION 
property which is recognized by the generator and replaced with the 
right thing in each generated configuration, though this leads to a 
hackish special syntax behind the scenes.  Another idea is to allow a 
separate custom command to be specified for each configuration, though 
this will lead to duplicate code and complicated loops in user code.  We 
have not figured out quite what to do.

Please submit a bug report here:

http://www.cmake.org/Bug

Thanks,
-Brad