WG21 P3168: Give std::optional Range Support

Authors: Marco Foco (@mfoco), Darius Neațu (@neatudarius), Barry Revzin (@brevzin), David Sankel (@camio)

Audience: Library Evolution

Description: The standard library lacks facilities for optional types when doing range operations. While other solutions proposed creating a new type, this paper explores the design alternative where std::optional is made into a range.

Note: This repo/paper is work for WG21: C++ Standards Committee Papers.

Published Revisions

• P3168R0:
  • https://wg21.link/P3168R0, 2024-02-28
  • source: P3168R0.md
  • status: reviewed in Tokyo 2024; forwarded to LEWG April Electronic Polls.
• P3168R1:
  • https://wg21.link/P3168R1, 2024-04-08
  • source: P3168R1.md
  • status: passed LEWG April Electronic Polls and forwarded to LWG for Saint Louis 2024.
• P3168R2:
  • https://wg21.link/P3168R2, 2024-06-25
  • source: P3168R2.md
  • status: reviewed and approved by LWG in Saint Louis 2024, forwarded to LWG Straw Polls.

Final status: Accepted into C++26!!!

Tracking Issues

• P3168 R2 Give std::optional Range Support
• [LWG motion 4 2024-06] P3168R2 Give std::optional Range Support
• Compiler cupport: cppreference: C++26 library features

Implementation experience

Implementation is done in Beman.Optional26.

TBD