std::indirect_unary_predicate - cppreference.com (original) (raw)
The concept indirect_unary_predicate specifies requirements for algorithms that call unary predicates as their arguments. The key difference between this concept and std::predicate is that it is applied to the type that I references, rather than I itself.
[edit] 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 | one of the requirements was defined in terms of std::iter_value_t<I>&which mishandled projections resulting in incompatibility with predicate F& | defined in terms of /*indirect-value-t*/<I>to correctly handle such projections |
| P2997R1 | C++20 | indirect_unary_predicate required F& to satisfy predicate withstd::iter_common_reference_t<I> | does not require |