Equivalence class in shell pattern does not work

[Lukáš Bařinka]

Configuration Information:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2 -fdebug-prefix-map=/build/bash-Kt4GMb/bash-5.0=.
-fstack-protector-strong -Wformat -Werror=format-security -Wall
-Wno-parentheses -Wno-format-security
uname output: Linux barinkl 4.19.0-1-amd64 #1 SMP Debian 4.19.12-1
(2018-12-22) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.0
Patch Level: 2
Release Status: release

Description:
Equivalence class in shell patterns does not work as expected. On the other
hand, equivalence class does work in regular expressions in bash.

The problem is in shell patterns inside Extended test [[ ]], globbing and
the case compound command.

Repeat-By:

#It does not work in SP
[[ éáö = *[[=e=][=a=][=o=]]* ]]; echo $?
1
[[ éáö == *[[=e=][=a=][=o=]]* ]]; echo $?
1

touch é á ö; echo [[=e=][=a=][=o=]]

case éáö in *[[=e=][=a=][=o=]]*) echo ok;; esac

#It works in RE as expected:
[[ éáö =~ [[=e=][=a=][=o=]] ]]; echo $?
0