error during catkin_make In function ‘void pcl_conversions::toPCL(const Header&, pcl::PCLHeader&)’

[RainySun-GT]

Hi，i'm using ROS-melodic on ubuntu 18.04.
I try to compile a catin workspace with the package "ar_track_alvar" in it. But it seems that there is something wrong about in the calling of pcl_conversions.h which is included in the file "ar_track_alvar/ar_track_alvar/include/ar_track_alvar/filter/kinect_filtering.h".
And the screenshots of the error is as follow.

It seems like a C++ grammar mistake.
The pcl_conversions package in my computer is installed by "sudo apt-get install ros-melodic-pcl-conversions".
Do you have any suggestion to fix this error?
I'm looking forwards to your reply.