I only tried to get Qt Base up and running. But Qt Declarative will be next, after Qt Base.

AFAIK Fil-C does not catch all memory safety bugs, for example some use-after-free are just not bugs but work as intended (you still access the original data/allocation). This means that it's not a sanitizer and code that runs fine on Fil-C may show UB when run normally.

eh, I daily-drive a -fsanitize=address -fsanitize=undefined build of Qt and actual memory bugs are almost never a thing - I think the only time I had some were in tooling executables such as qmllint, but not in the framework itself. Most of the bugs by large are more "behaviour" bugs.

Depends in which sense you want it to "catch" the bugs. As this readme notes/quotes,

> All memory safety errors are caught as Fil-C panics.

If your problem is a memory-based bug causing a crash, I think this would just... catch the memory-based bug and crash. Like, it'd crash more reliably. On the other hand, if you want to find and debug the problem, that might be a good thing.