Bug 667682 – [Future EAPI] enable "set -e", "set -o pipefail", and "shopt -s failglob" in ebuilds

• Product: Gentoo Hosted Projects
• Status: RESOLVED WONTFIX

[Description Patrick McLean 2018-10-03 23:11:45 UTC]

It would be a good idea if "set -e", "set -o pipefail", and "shopt -s failglob" were enabled for a future EAPI. This will reduce random issues that are hard to debug. This should be enabled in both the global scope and when running phase functions.

It basically gets us free trapping of unknown commands for example, along with lots of other advantages. This makes ebuilds less prone to silent failures.

[Comment 1 Ulrich Müller 2018-10-04 08:35:39 UTC]

We have previously discussed pipefail, and the conclusion was that it would make legitimate code fail. Examples include "command | grep -q" and "xz -d | tar xf -". See bug 566382.

[Comment 2 Ulrich Müller 2018-10-04 08:41:51 UTC]

"set -e" has been discussed too, in 2010:
https://archives.gentoo.org/gentoo-dev/message/a92f5f7bdadfaa746507fc11c38baa67

[Comment 3 Patrick McLean 2018-10-04 21:10:39 UTC]

The example in bug #566382 could also fail to catch failures that one intended to catch. If you actually expect the first command in a pipeline to fail, you can do something like:

{ ./configure --help 2>&1 || true; } | grep -q '^ *--docdir='; printf '%s\n' "${?}"

That would make it clear that the first command is expected to fail while not failing the whole pipeline.

Certainly "set -e" would make it so one has to check more carefully that the result of random commands is true, but adding "|| true" after a command that is expected might fail is probably a reasonable approach. You could also use the already existing "nonfatal" for these commands as well...

[Comment 4 Zac Medico 2018-11-18 10:12:58 UTC]

Unfortunately, set -e has some really odd behaviors in bash. For example, try this:

   bash -c "( set -e; false; echo bad; ) || echo good"

There are more examples here:

   http://mywiki.wooledge.org/BashFAQ/105

[Comment 5 Ulrich Müller 2018-11-18 15:42:53 UTC]

(In reply to Zac Medico from comment #4)

WONTFIX then?

[Comment 6 Zac Medico 2018-11-18 23:35:05 UTC]

Yes, sadly set -e appears to be essentially unusable.