So by default, they don't output anything if everything is well.
Discussion: https://www.postgresql.org/message-id/
867f8a1a-6cf0-d835-78d8-
0844e4936241%402ndquadrant.com
# Generate postgres.bki, postgres.description, postgres.shdescription,
# and pg_*_d.h headers.
-print "Generating BKI files and symbol definition headers...\n";
# version marker for .bki file
print $bki "# PostgreSQL $major_version\n";
Catalog::FindDefinedSymbolFromData($catalog_data{pg_language},
'INTERNALlanguageId');
-print "Generating fmgrtab.c, fmgroids.h, and fmgrprotos.h...\n";
-
# Collect certain fields from pg_proc.dat.
my @fmgr = ();