ASan was instrumenting none of the Flan half: it is an LLVM pass that
only touches functions carrying sanitize_address, which clang's C
frontend adds and hand-written IR does not. Globals get redzones either
way, which is why it looked right. emit.ml puts the attribute on every
define now, and a control asserts the report.
UBSan reaches no Flan code and no flag changes that -- its checks are
frontend-emitted branches, not a pass -- so shift UB and the NaN cast are
not answerable this way. Left as a compiler question, pinned by a control
that must not report.
Joseph Ferano
50ed2cbef0