22 Containers library [containers]

The headers <queue> and <stack> define the container adaptors queue, priority_­queue, and stack.

The container adaptors each take a Container template parameter, and each constructor takes a Container reference argument.

This container is copied into the Container member of each adaptor.

If the container takes an allocator, then a compatible allocator may be passed in to the adaptor's constructor.

Otherwise, normal copy or move construction is used for the container argument.

The first template parameter T of the container adaptors shall denote the same type as Container​::​value_­type.

For container adaptors, no swap function throws an exception unless that exception is thrown by the swap of the adaptor's Container or Compare object (if any).

A deduction guide for a container adaptor shall not participate in overload resolution if any of the following are true:

• (4.1)
  It has an InputIterator template parameter and a type that does not qualify as an input iterator is deduced for that parameter.
• (4.2)
  It has a Compare template parameter and a type that qualifies as an allocator is deduced for that parameter.
• (4.3)
  It has a Container template parameter and a type that qualifies as an allocator is deduced for that parameter.
• (4.4)
  It has an Allocator template parameter and a type that does not qualify as an allocator is deduced for that parameter.
• (4.5)
  It has both Container and Allocator template parameters, and uses_­allocator_­v<Container, Allocator> is false.