Posted the following to std.lang.c++, cross-posting here, mostly directed to David Abrahams: After reading N2855 - Rvalue References and Exception Safety (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2855.html) I'm still not confident that a new keyword `noexcept` would be optimal. Especially when the proposal combines this new keyword with a somewhat enhanced version of the already existing exception specification `throw(...)` to explicitly indicate that a move constructor or a destructor may throw exceptions. And at the same time propose to deprecate exception specifications altogether. I think that it would be better to use a simplified exception specification: - `throw()` to indicate that a function does not throw any exception, which is statically checked by the compiler. This would behave as `noexcept` in the N2855 proposal. - `throw(...)` to indicate that a function may throw any exception. Main use for throwing move constructors and throwing destructors. - Any other exception specification would be ill-formed and thus would require a compiler diagnostic. Update the new exception specification to behave as `noexcept` in N2855, where needed. Unfortunately I don't have a really good idea to implement something similar to the `noexcept` block as described in N2855. Perhaps a `try` block without a `catch` handler, perhaps someone else has a better idea? double sqrt(double); // may throw exceptions void f(double &x) throw() { if (x > 0) { x = sqrt(x); // ill-formed: sqrt(x) might throw an exception! } } void g(double &x) throw() { if (x > 0) { try { x = sqrt(x); } // okay: if sqrt(x) throws, invokes undefined behavior } } Rationale: - Exception specification as of C++98/C++03 are considered broken and discouraged. No need to deprecate, remove it entirely. - `throw()` is already used by a lot of libraries, for example boost, to indicate nothrow functions. With this proposal these functions would behave as `noexcept` with no change. - No new keywords are needed. Remove the following: exception-specification: throw ( [type-id-list]opt ) type-id-list: type-id type-id-list , type-id Add the following: no-throw-exception-specification: throw ( ) any-throw-exception-specification: throw ( ... ) What do you think? Regards, Anders Dalvander