PIPESTATUS differs from $? for compound command

[Ulrich Müller]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: x86_64-pc-linux-gnu-gcc
Compilation CFLAGS: -march=native -ggdb -O2 -pipe
uname output: Linux urania 6.6.62-gentoo #1 SMP Wed Nov 20 14:40:27 CET 2024 
x86_64 AMD Ryzen 7 PRO 7730U with Radeon Graphics AuthenticAMD GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.2
Patch Level: 37
Release Status: release

Description:
        For a compound command like "if" or "while" and with
        an unsuccessful test, the last element of PIPESTATUS is not the
        return status of the compound but that of the test command.
        For example, "if false; then :; fi" returns 0 but ${PIPESTATUS[0]}
        is 1.
        
        If the pipeline consists of more than one command, like
        "if false; then :; fi | true" or "true | if false; then :; fi"
        then it behaves as I would expect, i.e. all elements of
        PIPESTATUS are zero.

Repeat-By:
        $ if false; then :; fi
        $ echo "ret = $?, status = ${PIPESTATUS[*]}"
        ret = 0, status = 1