I've got a number of proposals for improving diagnostics and how we track source locations in GCC, which I'd like to present at Cauldron; extending location-tracking to cover: (a) all expressions (including constants, and uses of a decl), not just compound expressions (b) other syntactic elements (e.g. for implementing IDE integration) I also want to discuss how we might help advanced users track how GCC is optimizing their code via some kind of hybrid of the dump_file and diagnostics subsystems. I plan for most of the session to be interactive, hence this feels like something of a "diagnostics and location-tracking BoF".