Which parts of src/backend/nodes/print.c are used?

src/backend/nodes/print.c contains a number of functions that print node 
types, mostly to stdout.  Most of these are not actually used anywhere 
in the code.  Are they meant to be inserted into the code ad hoc for 
debugging?  Is anyone using these?

This file has clearly not been updated substantially in a long time, and 
functions like print_expr() are clearly outdated.

elog_node_display() and its callees are used, but I suppose these could 
be kept locally in postgres.c.

Other than that, is this file still needed?