message: Do not add duplicates to the list.
diff: @@ -6,8 +6,8 @@ function(filter_generator_expressions INPUT OUTPUT)
  # without (v3.16.x). Sometimes, it also has extra arguments. We need to do
  # at least a greedy regex also consuming the final `>` if present before
  # doing a non greedy one for the leftovers.
  - string(REGEX REPLACE "[$<A-Z_:]+SHELL:(.+)[>]+" "\\1" TMP "${TMP}")
  - string(REGEX REPLACE "[$<A-Z_:]*SHELL:(.+)[>]*" "\\1" TMP "${TMP}")
  + string(REGEX REPLACE "[$<A-Z_:]+SHELL:(.+)>+" "\\1" TMP "${TMP}")
  + string(REGEX REPLACE "[$<A-Z_:]*SHELL:(.+)>*" "\\1" TMP "${TMP}")
  string(REGEX REPLACE ".+INTERFACE:.+>" "" TMP "${TMP}")
  string(REGEX REPLACE "\$<COMMA>" "," TMP "${TMP}")
  # Ignore hwloc include if it is the internal one
  @@ -32,8 +32,8 @@ macro(ginkgo_interface_libraries_recursively INTERFACE_LIBS)
  if (GINKGO_INTERFACE_LIBS_LINK_FLAGS)
  filter_generator_expressions("${GINKGO_INTERFACE_LIBS_LINK_FLAGS}"
  GINKGO_INTERFACE_LIB_NAME)
  - list(APPEND GINKGO_INTERFACE_LIBS_FOUND "${GINKGO_INTERFACE_LIB_NAME}")
  - elseif (NOT "${GINKGO_INTERFACE_LIB_NAME}" IN_LIST GINKGO_INTERFACE_LIBS_FOUND)
  + endif()
  + if (NOT "${GINKGO_INTERFACE_LIB_NAME}" IN_LIST GINKGO_INTERFACE_LIBS_FOUND)
  list(APPEND GINKGO_INTERFACE_LIBS_FOUND "${GINKGO_INTERFACE_LIB_NAME}")
  endif()
  @@ -97,6 +97,7 @@ macro(ginkgo_interface_information)
  # Format and store the interface libraries found
  list(REMOVE_DUPLICATES GINKGO_INTERFACE_LIBS_FOUND)
  + list(REMOVE_ITEM GINKGO_INTERFACE_LIBS_FOUND "")
  string(REPLACE ";" " "
  GINKGO_FORMATTED_INTERFACE_LIBS_FOUND "${GINKGO_INTERFACE_LIBS_FOUND}")
  set(GINKGO_INTERFACE_LINK_FLAGS
  @@ -104,6 +105,7 @@ macro(ginkgo_interface_information)
  unset(GINKGO_INTERFACE_LIBS_FOUND)
  # Format and store the interface cflags found
  list(REMOVE_DUPLICATES GINKGO_INTERFACE_CFLAGS_FOUND)
  + list(REMOVE_ITEM GINKGO_INTERFACE_CFLAGS_FOUND "")
  string(REPLACE ";" " "
  GINKGO_FORMATTED_INTERFACE_CFLAGS_FOUND "${GINKGO_INTERFACE_CFLAGS_FOUND}")
  set(GINKGO_INTERFACE_CXX_FLAGS "${GINKGO_FORMATTED_INTERFACE_CFLAGS_FOUND}")
  