This is rather unfortunate: $ echo xn--iebx.example | LC_ALL=en_US idn2 -d ??.example $ rpm -qf /usr/bin/idn2 libidn2-2.0.4-3.fc27.x86_64 I would expect an error or the original input string in this situation. This also happens when calling idn2_to_unicode_lzlz with zero flags. I do not see a idn2_flags value to change this behavior.
Reported to upstream https://gitlab.com/libidn/libidn2/issues/46
This has now been fixed upstream: https://gitlab.com/libidn/libidn2/commit/6fa9aa172ba262356502aec2a3047610251c6093 https://gitlab.com/libidn/libidn2/commit/dd11133faa276744fb2b11424778c62820bbd547 Would you please release a fixed version to Fedora, ideally back to Fedora 27? I can help with that if you want.
After applying patches mentioned in comment #2: $ echo xn--iebx.example | LC_ALL=en_US idn2 -d idn2: decode: string encoding error $
libidn2-2.0.4-4.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-32c1a599bd
libidn2-2.0.4-4.fc27 has been submitted as an update to Fedora 27. https://bodhi.fedoraproject.org/updates/FEDORA-2018-53a56c4e63
libidn2-2.0.4-4.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2018-7e427d9b0d
libidn2-2.0.4-4.el7 has been submitted as an update to Fedora EPEL 7. https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2018-03a2d7ceb1
libidn2-2.0.4-4.el6 has been submitted as an update to Fedora EPEL 6. https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2018-f5e7ae19a8
libidn2-2.0.4-4.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-7e427d9b0d
libidn2-2.0.4-4.fc27 has been pushed to the Fedora 27 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-53a56c4e63
libidn2-2.0.4-4.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-32c1a599bd
libidn2-2.0.4-4.el6 has been pushed to the Fedora EPEL 6 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2018-f5e7ae19a8
libidn2-2.0.4-4.el7 has been pushed to the Fedora EPEL 7 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2018-03a2d7ceb1
libidn2-2.0.4-4.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.
libidn2-2.0.4-4.fc27 has been pushed to the Fedora 27 stable repository. If problems still persist, please make note of it in this bug report.
libidn2-2.0.4-4.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.
libidn2-2.0.4-4.el7 has been pushed to the Fedora EPEL 7 stable repository. If problems still persist, please make note of it in this bug report.
libidn2-2.0.4-4.el6 has been pushed to the Fedora EPEL 6 stable repository. If problems still persist, please make note of it in this bug report.