Segmentation fault when opening Obj-C++ file (.mm)

I have a cmake project that has C++ and Obj-C++ source files. Opening one of the Obj-C++ files leads to a crash of QtCreator with a segmentation fault after a few seconds. Maybe the internal parser chokes on something in the file.

Other Obj-C++ files in the project open fine. However, I should note that unlike the C++ files, ALL Obj-C++ are not properly recognized as being part of the project and thus I guess the parser uses default and not project-specific settings (is this expected with Obj-C++?).

Launching from the terminal all I see is:

[1]    66701 segmentation fault  ./Qt\ Creator.app/Contents/MacOS/Qt\ Creator

I'm not sure how I can get more logs on where the crash happens exactly. I cannot share the project, unfortunately, but if I have some pointers, I could try to create a minimal repro.