16 Library introduction [library]

16.5 Library-wide requirements [requirements]

16.5.4 Constraints on programs [constraints]

16.5.4.8 Other functions [res.on.functions]

In certain cases (replacement functions, handler functions, operations on types used to instantiate standard library template components), the C++ standard library depends on components supplied by a C++ program.
If these components do not meet their requirements, this document places no requirements on the implementation.
In particular, the effects are undefined in the following cases:
  • for replacement functions, if the installed replacement function does not implement the semantics of the applicable Required behavior: paragraph.
  • for handler functions ([new.handler], [terminate.handler]), if the installed handler function does not implement the semantics of the applicable Required behavior: paragraph
  • for types used as template arguments when instantiating a template component, if the operations on the type do not implement the semantics of the applicable Requirements subclause ([allocator.requirements], [container.requirements], [iterator.requirements], [algorithms.requirements], [numeric.requirements]).
    Operations on such types can report a failure by throwing an exception unless otherwise specified.
  • if any replacement function or handler function or destructor operation exits via an exception, unless specifically allowed in the applicable Required behavior: paragraph.
  • if an incomplete type ([basic.types]) is used as a template argument when instantiating a template component or evaluating a concept, unless specifically allowed for that component.