[diff.cpp20.library]

# Annex C (informative) Compatibility [[diff]](./#diff)

## C.2 C++ and ISO C++ 2020 [[diff.cpp20]](diff.cpp20#library)

### C.2.7 [[library]](library "16 Library introduction"): library introduction [diff.cpp20.library]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/compatibility.tex#L608)

**Affected subclause:** [[headers]](headers)  


**Change:** New headers[.](#1.sentence-1)

  


**Rationale:** New functionality[.](#1.sentence-2)

  


**Effect on original feature:** The following C++ headers are new:[<expected>](expected.syn#header:%3cexpected%3e "22.8.2 Header <expected> synopsis [expected.syn]"),[<flat_map>](flat.map.syn#header:%3cflat_map%3e "23.6.7 Header <flat_­map> synopsis [flat.map.syn]"),[<flat_set>](flat.set.syn#header:%3cflat_set%3e "23.6.10 Header <flat_­set> synopsis [flat.set.syn]"),[<generator>](generator.syn#header:%3cgenerator%3e "25.8.2 Header <generator> synopsis [generator.syn]"),[<mdspan>](mdspan.syn#header:%3cmdspan%3e "23.7.3.2 Header <mdspan> synopsis [mdspan.syn]"),[<print>](print.syn#header:%3cprint%3e "31.7.4 Header <print> synopsis [print.syn]"),[<spanstream>](span.streams.overview#header:%3cspanstream%3e "31.9.1 Overview [span.streams.overview]"),[<stacktrace>](stacktrace.syn#header:%3cstacktrace%3e "19.6.2 Header <stacktrace> synopsis [stacktrace.syn]"),[<stdatomic.h>](stdatomic.h.syn#header:%3cstdatomic.h%3e "32.5.12 C compatibility [stdatomic.h.syn]"), and[<stdfloat>](stdfloat.syn#header:%3cstdfloat%3e "17.4.2 Header <stdfloat> synopsis [stdfloat.syn]")[.](#1.sentence-3)

Valid C++ 2020 code that #includes headers with these names may be
invalid in this revision of C++[.](#1.sentence-4)