How to prevent nested function failures being missed in bash

The following code:

#!/usr/bin/env bash

set -Eeuo pipefail
shopt -s huponexit
shopt -s inherit_errexit

function child_function {
	return 1
}
function parent_function {
	child_function
	echo "parent noticed child exit code as $?"
}
function grandparent_function {
	local ec
	ec=0 && parent_function || ec="$?"
	echo "grandparent noticed parent exit code as $ec"
}

grandparent_function

Will surprisingly output:

parent noticed child exit code as 1
grandparent noticed parent exit code as 0

Changing the code to:

#!/usr/bin/env bash

set -Eeuo pipefail
shopt -s huponexit
shopt -s inherit_errexit

function child_function {
	return 1
}
function parent_function {
	child_function || return "$?"
	echo "parent noticed child exit code as $?"
}
function grandparent_function {
	local ec
	ec=0 && parent_function || ec="$?"
	echo "grandparent noticed parent exit code as $ec"
}

grandparent_function

Returns the expected result of:

grandparent noticed parent exit code as 1

Is there an additional setting that I need to set to fix this? Or is this a bug in bash?

The reason I believe it is a bug, is that changing the code to not use the || ec="$?" will respect the -e/errexit option (Exit immediately if a command exits with a non-zero status) and have each failed function exit immediately:

#!/usr/bin/env bash

set -Eeuo pipefail
shopt -s huponexit
shopt -s inherit_errexit

function child_function {
	return 1
}
function parent_function {
	child_function
	echo "parent noticed child exit code as $?"
}
function grandparent_function {
	parent_function
	echo "grandparent noticed parent exit code as $?"
}

grandparent_function

Outputs nothing and returns exit code 1

Thanks to the commenters:

• choroba
• kamilcuk
• pjh

And these supporting resources:

• https://stackoverflow.com/a/32201766/130638
• https://stackoverflow.com/a/70992989/130638
• https://unix.stackexchange.com/q/447519/50703
• https://mywiki.wooledge.org/BashPitfalls#set_-euo_pipefail
• https://unix.stackexchange.com/a/645365/50703
• https://stackoverflow.com/q/19789102/130638
• https://www.austingroupbugs.net/view.php?id=537

I created this workaround for the question's code sample using the subshell technique:

#!/usr/bin/env bash

set -e

function child_function {
	return 1
}
function parent_function {
	child_function
	echo "parent noticed child exit code as $?"
}
function grandparent_function {
	local ec=0
	set +e; (set -e; parent_function); ec="$?"; set -e
	echo "grandparent noticed parent exit code as $ec"
}

grandparent_function

However, the subshell technique prevents side effects, as modifications do not escape the subshell.

I spent a few more days on this issue, and created a gist with various techniques, including one that works with side effects:

https://gist.github.com/balupton/21ded5cefc26dc20833e6ed606209e1b