std::experimental::nonesuch

 

C++

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Experimental

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Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

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Extensions for parallelism 2 (parallelism TS v2)

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Extensions for concurrency 2 (concurrency TS v2)

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Library fundamentals v2

experimental::propagate_const

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detection idiom

uniform container erasure

logical operator type traits

 

Defined in header <experimental/type_traits>
struct nonesuch {     ~nonesuch() = delete;     nonesuch(nonesuch const&) = delete;     void operator=(nonesuch const&) = delete; };		(library fundamentals TS v2)

std::experimental::nonesuch is a class type used by std::experimental::detected_t to indicate detection failure.

nonesuch has no default constructor or initializer-list constructor, and is not an aggregate.

Notes

nonesuch cannot be constructed, destroyed, or copied.

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
LWG 2960	LFTSv2	nonesuch may be an aggregate and has an implicit conversion sequence from {}	made non-aggregate and removed ICS