std::experimental::nonesuch

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

Concepts (concepts TS)

Ranges (ranges TS)

Mathematical special functions (special functions TR)

 

Library fundamentals v2

experimental::propagate_const

experimental::not_fn

experimental::observer_ptr

experimental::make_array

experimental::to_array

experimental::ostream_joiner

experimental::gcd

experimental::lcm

experimental::source_location

experimental::randint

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