QtCreator 4.8.0 introduced support for the LSP last month : https://blog.qt.io/blog/2018/12/06/qt-creator-4-8-0-releasedI think I'm going to add it to the list of editors to look into and perhaps try to make a plugin for it.
Correction: a language server can simply be set up in the LSP plugin's options after the plugin has been enabled, so some amount of D support is achievable already.
