errortracing inside || and eval

[Tycho Kirchner]

Hi!
We would like to run an error trap inside a function, even if it is called within 
|| -> func || true.
While bash's manpage documents in the trap-section that no error trap runs
"if the failed command ... is part of a command executed in ||", we found the following 
workaround, using "eval":

test.sh
_________________________________-

func(){
    # works if inside 'eval', otherwise trap '..' ERR has no effect.
    eval "trap 'echo local error trap >&2;return 42' ERR; false"
    echo func
    return 3
}

set -o errtrace
trap 'echo global error trap >&2; exit 1' ERR

func || echo bye $?
_________________________________

$ ./test.sh
local error trap
bye 42



Is this a bug or expected behavior, we can rely on?
Thanks in advance
Tycho and Konstantin