fatal error not produced for all unknown modifiers in --posix mode

[Arkadiusz Drabczyk]

In gawk.info it says:

"C programmers may be used to supplying additional modifiers ('h',
'j', 'l', 'L', 't', and 'z') in 'printf' format strings.  These are
not valid in 'awk'.  Most 'awk' implementations silently ignore them.
If '--lint' is provided on the command line (*note Options::), 'gawk'
warns about their use.  If '--posix' is supplied, their use is a fatal
error."

But the fatal error is not produced for all unknown modifiers in
--posix mode:

$ cat modifiers.sh
#!/usr/bin/env sh

gawk --posix --lint 'BEGIN { printf "%hu\n", 12 }'
gawk --posix --lint 'BEGIN { printf "%lu\n", 12 }'
gawk --posix --lint 'BEGIN { printf "%Lu\n", 12 }'

gawk --posix --lint 'BEGIN { printf "%ju\n", 12 }'
gawk --posix --lint 'BEGIN { printf "%tu\n", 12 }'
gawk --posix --lint 'BEGIN { printf "%zu\n", 12 }'
$ ./modifiers.sh
gawk: cmd. line:1: warning: `h' is meaningless in awk formats; ignored
gawk: cmd. line:1: fatal: `h' is not permitted in POSIX awk formats
gawk: cmd. line:1: warning: `l' is meaningless in awk formats; ignored
gawk: cmd. line:1: fatal: `l' is not permitted in POSIX awk formats
gawk: cmd. line:1: warning: `L' is meaningless in awk formats; ignored
gawk: cmd. line:1: fatal: `L' is not permitted in POSIX awk formats
gawk: cmd. line:1: warning: ignoring unknown format specifier character `j': no 
argument converted
gawk: cmd. line:1: warning: [s]printf: format specifier does not have control 
letter
gawk: cmd. line:1: warning: too many arguments supplied for format string
%ju
gawk: cmd. line:1: warning: ignoring unknown format specifier character `t': no 
argument converted
gawk: cmd. line:1: warning: [s]printf: format specifier does not have control 
letter
gawk: cmd. line:1: warning: too many arguments supplied for format string
%tu
gawk: cmd. line:1: warning: ignoring unknown format specifier character `z': no 
argument converted
gawk: cmd. line:1: warning: [s]printf: format specifier does not have control 
letter
gawk: cmd. line:1: warning: too many arguments supplied for format string
%zu

As you can fatal error is produced for h, l and L but it's not
produced for j, t and z.

I'm not sure I interpret the docs correctly - should the fatal error
be produced only for types which are explicitly handled in awk or for
all of them (I believe in that case a new case is needed in
format_tree())?

-- 
Arkadiusz Drabczyk <arkadiusz@drabczyk.org>