boolean-testable

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Concepts library

Core language concepts
same_as (C++20)
derived_from (C++20)
convertible_to (C++20)
common_reference_with (C++20)
common_with (C++20)
integral (C++20)
signed_integral (C++20)
unsigned_integral (C++20)
floating_point (C++20)
swappableswappable_with (C++20)(C++20)
destructible (C++20)
constructible_from (C++20)
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assignable_from (C++20)

Comparison concepts
equality_comparableequality_comparable_with (C++20)(C++20)
totally_orderedtotally_ordered_with (C++20)(C++20)
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movable (C++20)
copyable (C++20)
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invocableregular_invocable (C++20)(C++20)
predicate (C++20)
relation (C++20)
equivalence_relation (C++20)
strict_weak_order (C++20)

Exposition-only concepts
*boolean-testable* (C++20)

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template<class B> concept __boolean_testable_impl=std::convertible_to<B,bool>;	(1)	(since C++20) (exposition only*)
template<class B> concept boolean-testable= __boolean_testable_impl<B>&& requires(B&& b){ {!std::forward<B>(b)}-> __boolean_testable_impl; };	(2)	(since C++20) (exposition only*)

The exposition-only conceptboolean-testable specifies the requirements for expressions that are convertible tobool and for which the logical operators have the usual behavior (includingshort-circuiting), even for two differentboolean-testable types.

Formally, to model the exposition-only concept__boolean_testable_impl, the type must not define any memberoperator&& andoperator||, and no viable non-memberoperator&& andoperator|| may be visible byargument-dependent lookup. Additionally, given an expressione such thatdecltype((e)) isB,boolean-testable is modeled only ifbool(e)==!bool(!e).