std:: indirect_strict_weak_order

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C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
(C++20)
indirect_strict_weak_order
(C++20)
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
Defined in header <iterator>
template < class F, class I1, class I2 = I1 >

concept indirect_strict_weak_order =
std:: indirectly_readable < I1 > &&
std:: indirectly_readable < I2 > &&
std:: copy_constructible < F > &&
std:: strict_weak_order
< F & , /*indirect-value-t*/ < I1 > , /*indirect-value-t*/ < I2 >> &&
std:: strict_weak_order
< F & , /*indirect-value-t*/ < I1 > , std:: iter_reference_t < I2 >> &&
std:: strict_weak_order
< F & , std:: iter_reference_t < I1 > , /*indirect-value-t*/ < I2 >> &&
std:: strict_weak_order

< F & , std:: iter_reference_t < I1 > , std:: iter_reference_t < I2 >> ;
(since C++20)

The concept indirect_strict_weak_order specifies requirements for algorithms that call strict weak orders as their arguments. The key difference between this concept and std::strict_weak_order is that it is applied to the types that I1 and I2 references, rather than I1 and I2 themselves.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
P2609R3 C++20 some requirements were defined in terms of
std:: iter_value_t < I > & which mishandled projections
resulting in incompatibility with strict weak order F & 		defined in terms of
/*indirect-value-t*/ < I > to
correctly handle such projections
P2997R1 C++20 indirect_strict_weak_order required F & to satisfy
strict_weak_order with std:: iter_common_reference_t < I > 		does not require
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