Can't speak to how everyone else is using it but at my job we run all of our unit tests under Fil-C as part of CI, in addition to the UBASAN, TSAN, and Valgrind pipelines we already had for them.

There's a whole lot of C and C++ software out there, and Fil-C makes it memory safe, frequently with minimal work.

Memory safety for existing C and C++ codebase.