I propose adding noexcept as an attribute.  It would be used after a function call to a noexcept(false) function.  It asserts that, in that context, the function will not throw any exceptions.  I also propose that, if a function that only has calls to noexcept functions, or calls with the [[noexcept]] attribute, the compiler must emit a diagnostic (presumably a warning) if the function is noexcept(false).