[BUG] libcudf fails to configure with unpinned dependencies

[jlowe]

Describe the bug
After #16360 a cmake configure of libcudf with unpinned dependencies fails with the error:

-- CPM: Using local package [email protected]
CMake Error at build/_deps/rapids-cmake-src/rapids-cmake/cpm/detail/pinning_write_file.cmake:278 (string):
  string sub-command JSON failed parsing json string: * Line 145, Column 4

    Missing ',' or '}' in object declaration

  .
Call Stack (most recent call first):
  build/_deps/rapids-cmake-src/rapids-cmake/cpm/detail/pinning_root_dir_hook.cmake:29 (rapids_cpm_pinning_write_file)
  build/_deps/rapids-cmake-src/rapids-cmake/cpm/generate_pinned_versions.cmake:102 (include)
  CMakeLists.txt:DEFERRED


-- Configuring incomplete, errors occurred!

Steps/Code to reproduce bug

$ pwd
/home/jlowe/src/spark-rapids-jni/thirdparty/cudf/cpp/build

$ cat setup.cmake
string(TOLOWER "${CUDF_DEPENDENCY_PIN_MODE}" CUDF_DEPENDENCY_PIN_MODE)
if(NOT (CUDF_DEPENDENCY_PIN_MODE STREQUAL pinned OR
        CUDF_DEPENDENCY_PIN_MODE STREQUAL latest))
  message(FATAL_ERROR "The CUDF_DEPENDENCY_PIN_MODE variable must be set to either `pinned` or `latest`.")
 endif()

function(set_rapids_cmake_pin_sha1)
  set(rapids-cmake-sha "${rapids-cmake-sha}" PARENT_SCOPE)

  message(STATUS "Pinning rapids-cmake SHA1 to ${rapids-cmake-sha}")
endfunction()

# We need to set the rapids-cmake SHA1 before any CMake code in libcudf is executed when
# we are in pin mode. Otherwise we will use the latest rapids-cmake version since that
# is what cudf does via `fetch_rapids.cmake`
if(CUDF_DEPENDENCY_PIN_MODE STREQUAL pinned)
  # Extract the rapids sha1 from the file
  file(READ "${CMAKE_CURRENT_LIST_DIR}/rapids-cmake.sha" rapids-cmake-sha)
  string(STRIP rapids-cmake-sha "${rapids-cmake-sha}")
  string(REPLACE "\n" "" rapids-cmake-sha "${rapids-cmake-sha}")
  set(rapids-cmake-sha "${rapids-cmake-sha}" CACHE STRING "rapids-cmake sha to use" FORCE)
  message(STATUS "Pinning rapids-cmake SHA1 [${rapids-cmake-sha}]")
else()
  set(rapids-cmake-fetch-via-git "ON" CACHE STRING "Make sure rapids-cmake is cloned so we can get SHA value" FORCE)
endif()

# We need to use a project() call hook, since rapids-cmake cpm_init()
# can't be called from a `-C` CMake file
set(CMAKE_PROJECT_TOP_LEVEL_INCLUDES "${CMAKE_CURRENT_LIST_DIR}/add_dependency_pins.cmake" CACHE FILEPATH "" )

$ cat add_dependency_pins.cmake
if(NOT DEFINED rapids-cmake-dir)
  include(../cudf/rapids_config.cmake)
endif()

include(rapids-cpm)
rapids_cpm_init()

function(add_override_if_requested)
  if(CUDF_DEPENDENCY_PIN_MODE STREQUAL pinned)
    include(${rapids-cmake-dir}/cpm/package_override.cmake)
    rapids_cpm_package_override(${CMAKE_CURRENT_FUNCTION_LIST_DIR}/versions.json)

    message(STATUS "Pinning CUDF dependencies to values found in ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/versions.json")
  else()
    include(${rapids-cmake-dir}/cpm/generate_pinned_versions.cmake)
    rapids_cpm_generate_pinned_versions(OUTPUT ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/versions.json)

    message(STATUS "Building with latest CUDF dependencies (saving pinned versions to ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/versions.json)")
  endif()
endfunction()
add_override_if_requested()

$ cmake -DCMAKE_CUDA_ARCHITECTURES=89-real -DCUDF_DEPENDENCY_PIN_MODE=latest -DCUDF_ENABLE_ARROW_S3=OFF -C=setup.cmake ..

Expected behavior
libcudf should configure successfully as it did before #16360

[jlowe]

Should be fixed by rapidsai/rapids-cmake#655

[ttnghia]

Close as it is fixed.