C++20

Toronto 2017 – Prague 2020 · N4861 (final draft) · ISO/IEC 14882:2020
311papers adopted
37features touched
9plenaries
← C++17C++23 →Show only C++20 on the map

Language

18 features
Small language features (C++20)22 papersThree-way comparison (<=>)13 papersConcepts12 papersconstexpr expansion (C++20)12 papersModules11 papersLambda improvements (C++20)8 papersAttributes (C++20)5 paperschar8_t & Unicode (C++20)5 papersCTAD improvements (C++20)5 papersDeprecations & removals (C++20)5 papersContracts (C++20, removed)4 papersDesignated initializers & aggregates4 papersStructured bindings (C++20)4 papersImplicit move & return statements3 papersClass types in non-type template parameters2 papersCoroutines2 papersAttributes (C++17)also C++171 paperImplicit object creation1 paper

Library

16 features · 3 housekeeping
Utilities & type traits (C++20)20 papersRanges19 papersContainers & algorithms (C++20)12 papersAtomics & memory model (C++20)11 papersBit manipulation & numeric utilities11 papersLanguage support utilities (C++20)11 papersLibrary constexpr-ification (C++20)11 papersStrings & I/O (C++20)11 papersstd::span7 papersCalendars & time zones6 papersStandard library concepts6 papersSynchronization library & jthread6 papersstd::format5 papersElementary string conversions (<charconv>)also C++171 paperFilesystem libraryalso C++171 paperParallel algorithmsalso C++171 paperCore & Library issue resolutionsalso 6 others28 papersLibrary specification rewrite (Mandates/Constraints)17 papersNB-comment omnibus & housekeepingalso 5 others8 papers

Papers per plenary

Cologne 2019 was the busiest plenary: 60 papers adopted into C++20.

TorontoJul 201717AlbuquerqueNov 201728JacksonvilleMar 201819RapperswilJun 201832San DiegoNov 201841KonaFeb 201930CologneJul 201960BelfastNov 201940PragueFeb 202044

Idioms in C++20

what changed in practice · from the Atlas
Parameter passingCore semanticsOwnership & lifetimesCore semanticsValue vs. reference semanticsCore semanticsMove semanticsCore semanticsInitializationCore semanticsConst & constexpr correctnessCore semanticsClass designDesignError handlingDesignPolymorphism choiceDesignAPI boundaries & vocabulary typesDesignCustomization pointsGeneric & compile-timeConstraint styleGeneric & compile-timeNamed idiomsGeneric & compile-timeAlgorithms & ranges over raw loopsCode-levelCasting disciplineCode-levelConcurrency idiomsCode-levelPhysical designCode-levelCoroutine machineryCompile-time & language mechanicsAsync compositionCompile-time & language mechanicsUB & object lifetimeCompile-time & language mechanicsDeclaration styleCompile-time & language mechanicsLambda idiomsCompile-time & language mechanicsName lookup hygieneCompile-time & language mechanicsAllocator awarenessMemory & performancePerformance idiomsMemory & performanceCode-size controlMemory & performanceGlobal state & init orderMemory & performanceString handlingText, numbers, timeInteger hygieneText, numbers, timechrono disciplineText, numbers, timeComparators & hashingText, numbers, timeC interop & ABIBoundaries & practiceFreestanding & embedded subsetBoundaries & practiceFeature detection & migrationBoundaries & practiceTooling-encoded idiomBoundaries & practice