Hello,
I found this by an accident and I think it is a bug in gawk 4.1.3 and 4.1.4
$ gawk 'BEGIN {for (KEY in PROCINFO) print KEY, PROCINFO[KEY];}'
group9 116
ppid 22129
pgrpid 2890
api_major 1
group10 1000
api_minor 1
group1 4
gid 1000
mpfr_version GNU MPFR 4.0.1
group2 20
egid 1000
group3 24
gawk: cmd. line:1: fatal: attempt to use array `PROCINFO["identifiers"]' in a scalar context
$ gawk 'BEGIN {print "identifiers" in PROCINFO;}'
1
$ gawk 'BEGIN {print PROCINFO["identifiers"];}'
gawk: cmd. line:1: fatal: attempt to use array `PROCINFO["identifiers"]' in a scalar context
BTW, note how error is reported, there are two different appostrofes (` & '), it looks like other, cosmetic, bug.