[diff.cpp03.class]

Affected subclauses: [class.default.ctor], [class.dtor], [class.copy.ctor], and [class.copy.assign]

Change: Implicitly-declared special member functions are defined as deleted when the implicit definition would have been ill-formed.

Rationale: Improves template argument deduction failure.

Effect on original feature: A valid C++ 2003 program that uses one of these special member functions in a context where the definition is not required (e.g., in an expression that is not potentially evaluated) becomes ill-formed.

Affected subclause: [class.dtor]

Change: User-declared destructors have an implicit exception specification.

Rationale: Clarification of destructor requirements.

Effect on original feature: Valid C++ 2003 code may execute differently in this revision of C++.

In particular, destructors that throw exceptions will call std::terminate (without calling std::unexpected) if their exception specification is non-throwing.