Description of problem: Version 4.5 was releases. Version-Release number of selected component (if applicable): qt-creator-4.2.2-7.fc26.x86_64 Please update it.
If I'm not mistaken, llvm/clang in f26 is too old for qt-creator-4.5.
qt-creator-4.5.0-1.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2017-39f7ef8665
qt-creator-4.5.0-1.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-2017-39f7ef8665
qt-creator-4.5.0-1.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.