[struct_pb][bug]fix compile error #1535

Job	Run time
ubuntu_clang (Release, OFF, ON)	3m 26s
ubuntu_clang (Release, OFF, OFF)	3m 32s
ubuntu_clang (Debug, OFF, ON)	3m 33s
ubuntu_clang (Debug, OFF, OFF)	3m 25s
ubuntu_clang_for_liburing (Release, OFF, ON)	2m 48s
ubuntu_clang_for_liburing (Debug, OFF, ON)	2m 52s
ubuntu_clang_pb (Release, OFF, ON)	2m 0s
ubuntu_clang_pb (Release, OFF, OFF)	2m 2s
ubuntu_clang_pb (Debug, OFF, ON)	1m 50s
ubuntu_clang_pb (Debug, OFF, OFF)	1m 38s
ubuntu_clang10 (Release)	52s
ubuntu_clang10 (Debug)	1m 6s
	29m 4s

Provide feedback