This is mostly straight-forward, but some things are worth noting: 1. Yes, this is necessary. The noexcept operator looks for noexcept tagging, not at the contents of the function to determine whether to return true. The more conditionally-noexcept functions are used, the more important it becomes that low-level classes are correctly marked noexcept. In that, it is like constexpr. 2. In accordance with the rules governing noexcept specifications for the standard library itself, the operator/-family of functions are not marked as noexcept, since they have preconditions and thus a narrow contract. Narrow-contract functions should not be noexcept. All other functions have wide contracts (ie. no preconditions). Change-Id: I9fc94218a2728c272483f9c2826c265f5b11c9b4 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>