It seems that explanation for the contents of the pid file has moved to pidfile.h, but the comments in CreateLockFile() still point to miscadmin.h.
The attached patch updates those pointers.
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c index 83c9514856..de554e28cf 100644 --- a/src/backend/utils/init/miscinit.c +++ b/src/backend/utils/init/miscinit.c @@ -822,7 +822,7 @@ GetUserNameFromId(Oid roleid, bool noerr) * ($DATADIR/postmaster.pid) and Unix-socket-file lockfiles ($SOCKFILE.lock). * Both kinds of files contain the same info initially, although we can add * more information to a data-directory lockfile after it's created, using - * AddToDataDirLockFile(). See miscadmin.h for documentation of the contents + * AddToDataDirLockFile(). See pidfile.h for documentation of the contents * of these lockfiles. * * On successful lockfile creation, a proc_exit callback to remove the @@ -1089,7 +1089,7 @@ CreateLockFile(const char *filename, bool amPostmaster, } /* - * Successfully created the file, now fill it. See comment in miscadmin.h + * Successfully created the file, now fill it. See comment in pidfile.h * about the contents. Note that we write the same first five lines into * both datadir and socket lockfiles; although more stuff may get added to * the datadir lockfile later.