parameter expansion null check fails for arrays when [*] or [@] is used

[Andreas Luik]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-redhat-linux-gnu' 
-DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib  -D_GNU_SOURCE -DRECYCLES_PIDS 
-DDEFAULT_PATH_VALUE='/usr/local/bin:/usr/bin'  -DSYSLOG_HISTORY -O2 -g -pipe 
-Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS 
-fexceptions -fstack-protector-strong -grecord-gcc-switches 
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 
-specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic 
-fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection 
-Wno-parentheses -Wno-format-security
uname output: Linux tst-rocky85.innovative-navigation.de 
4.18.0-348.el8.0.2.x86_64 #1 SMP Sun Nov 14 00:51:12 UTC 2021 x86_64 x86_64 
x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu

Bash Version: 4.4
Patch Level: 20
Release Status: release

Description:
        Bash fails to correctly test for parameter to be unset or null when the 
parameter is an array reference [*] or [@].

Repeat-By:

myvar[0]=
echo "${myvar[0]:+nonnull}"
<empty> -> OK
echo "${myvar[*]:+nonnull}"
nunnull -> not OK, because "${myvar[*]}" is null
echo "${myvar[@]:+nonnull}"
nunnull -> likewise not OK, because "${myvar[@]}" is null


-- 
Andreas Luik
Leiter Systemintegration & IT / Head of System Integration & IT
in-innovative navigation GmbH
Leibnizstr. 11
D-70806 Kornwestheim
tel: +49 7154 807171 | fax: +49 7154 807154
email: andreas.luik@innovative-navigation.de
www.innovative-navigation.de

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