cmake: build executables, libraries and bindings files on `obj` dir

[pabs3]

After building SPTAG and then running make clean and deleting the obj directory, the files generated by the build (including swig bindings files) are still present.

None
None/sptag-indexbuilder
None/sptag-server
None/sptag-client
None/_SPTAG.so
None/SPTAG.py
None/test
None/sptag-aggregator
None/SPTAGClient.py
None/libSPTAGLib.so
None/_SPTAGClient.so
None/libSPTAGLibStatic.a
None/sptag-indexsearcher
None/libDistanceUtils.a
Wrappers/inc/ClientInterface_pwrap.cpp
Wrappers/inc/CoreInterface_pwrap.cpp
Wrappers/inc/SPTAG.py
Wrappers/inc/SPTAGClient.py

The .gitignore file already ignores some of these files:

/Wrappers/inc/*wrap.*
/Wrappers/inc/*.py
/Wrappers/inc/*.java

Since these files are generated during the build, they should be output to the build dir (usually obj).

I noticed that on Windows, the CMakeLists.txt

$ grep -C4 CMAKE_BINARY_DIR CMakeLists.txt
if (WIN32)
    set(Boost_USE_STATIC_LIBS ON)

    set(CMAKE_CONFIGURATION_TYPES ${CMAKE_BUILD_TYPE})
    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})

    set (LIBRARY_OUTPUT_PATH ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR})
    set (EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR})
else()
    set (LIBRARY_OUTPUT_PATH "${PROJECT_SOURCE_DIR}/${CMAKE_BUILD_TYPE}/")
    set (EXECUTABLE_OUTPUT_PATH "${PROJECT_SOURCE_DIR}/${CMAKE_BUILD_TYPE}/")
endif()

I suggest that the output directories be set to ${CMAKE_BINARY_DIR} and that the swig bindings be built in ${CMAKE_BINARY_DIR} too.

[pabs3]

To be clear on the swig changes, in Wrappers/CMakeLists.txt, every reference to ${PROJECT_SOURCE_DIR}/Wrappers/inc/*wrap* or ${PROJECT_SOURCE_DIR}/Wrappers/inc/*.{py,java,cs} files need to be replaced with references to ${CMAKE_BINARY_DIR}/*wrap* and ${CMAKE_BINARY_DIR}/*.{py,java,cs}.

I have tested that the swig and output path changes fix this issue.

[pabs3]

In addition, the ADDITIONAL_CLEAN_FILES property needs to be set using set_property to the corresponding *wrap* and .{py,java,cs} for each of the targets in Wrappers/CMakeLists.txt, so that make clean within the obj directory works correctly. The property setting looks like this:

set_property(TARGET _SPTAG PROPERTY ADDITIONAL_CLEAN_FILES ${CMAKE_BINARY_DIR}/CoreInterface_pwrap.cpp ${CMAKE_BINARY_DIR}/SPTAG.py)