test=develop

paddle/fluid/memory/CMakeLists.txt

+# make the external project built first
+set(PADDLE_MEMORY_BUILD_DIR "${CMAKE_CURRENT_BINARY_DIR}/memory/build")
+add_custom_command(OUTPUT ${PADDLE_MEMORY_BUILD_DIR}/.timestamp
+        COMMAND ${CMAKE_COMMAND} -E touch ${PADDLE_MEMORY_BUILD_DIR}/.timestamp
+        DEPENDS ${external_project_dependencies})
+
 add_subdirectory(detail)
 add_subdirectory(allocation)
 cc_library(malloc SRCS malloc.cc DEPS place enforce allocator_facade)