Meta tracking Issue for in-place initialization #153825

This issue tracks the progress of in-place initialization in general.

This issue is not for discussion about specific proposals for in-place initialization. It's role is to track the overall progress and act as a link hub to currently ongoing and finished efforts. If you wish to discuss some subject related to in-place initialization, please find an existing appropriate issue below, create an new issue, or ask on zulip in the in-place init channel. (If a document, important discussion, issue etc, are missing or any of the links are dead, point at the wrong thing, or have a bad description text, ping me/the stream on zulip)

In-place initialization is a lang experiment (accepted in rust-lang/lang-team#336) about creating a language feature enabling the construction of Rust types in-place.

Feature Tracking Issues

• Tracking Issue for partial_init_locals #153699

Link Hub

• Beyond Refs Wiki - In-place initialization | Dec 2025-Now
• Design axioms & wanted features
  • Zulip - Wiki design axioms | Jan 2026 and Propose possible design axioms beyond-refs#24
  • Zulip - RfL Design Wishes | July 2025
• Phased initialization of locals Tracking Issue for partial_init_locals #153699
  • Zulip - empty structs | Jan 2026
  • Zulip - problems of phased init | Jan 2026
  • Zulip - intermediate milestone | Jan 2026
• Proposal: Init expressions
  • Move replacing Pin[Init]
    • Zulip - Move interactions | Jan 2026
    • Zulip - pinned futures in RfL | Nov 2025
  • Init fn | Feb 2026 with zulip discussion
  • Zulip - changing Box::new | Dec 2025
  • Zulip - compatibility with Try; be generic over Option, Result and no error | Oct 2025
  • Zulip - async init | June 2025
  • init expressions | June 2025 with zulip discussion
  • Language feature: in-place construction | Oct 2022
  • pin-init crate | April 2022-Now
• Proposal: Out pointers
  • Raw pointers are too lax for in-place (re-)init tasks | Mar 2026 with zulip discussion
  • Out ptr but less verbose, take two | Feb 2026 with zulip discussion
  • Zulip - initializing a box with &uninit | Feb 2026
  • [Zulip - outptrs | Feb 2026]
  • Zulip - automatic notarization | Jan 2026 resulted in Sketch &uninit and Initialised proof API beyond-refs#25 and a beyond-refs wiki entry on &uninit that was improved in Zulip - outptrs are exactly the right amoutn of verbose | Feb 2026
  • Zulip - what about ?Sized | Nov 2025
  • Zulip - Do we need <- | Nov 2025
  • Notarization v2 | Nov 2025 with zulip discussion
  • Desugaring to init expressions | Sep 2025
  • Notarization of init proofs | Sep 2025 with zulip discussion
  • In-place initialization via outptrs | July 2025 with zulip discussion
  • Zulip - &out | June 2025
• Proposal: Guaranteed return value optimization
  • related: custom Result-ABI
    • Zulip - more ABI ideas | Nov 2025
    • Zulip - bigger discussion | Nov 2025
    • Zulip - initial idea | Nov 2025
  • RFC Draft | Oct 2025 with zulip discussion
  • Zulip - limits | June 2025
  • Improving placement-by-return | Sep 2022
  • RFC: Placement by return rfcs#2884
• High level view: placing functions
  • Zulip - placing fn as coroutines | Jan 2026
  • Zulip - placing Fn vs Init | Dec 2025
  • Zulip - interactions with effects | Oct 2025
  • Zulip - framing as high-level view
  • Placing Arguments | Aug 2025
  • Placing Functions | July 2025 with zulip discussion
• Design Meeting | July 2025
  • Zulip - Box::new | Aug 2025
  • Zulip - design meeting | July 2025
• Problem: integrating with other effects
  • Zulip - init as an effect in effing-mad | Feb 2026
  • Zulip - is init an effect | Feb 2026
  • Zulip - out-ptrs are too verbose take three | Feb 2026
  • Fundamental Issue of Effects and In-place-init | Nov 2025 with zulip discussion
• Problem: Async
  • Zulip - async forget problem | July 2025
• Problem: Code-ordering
  • Zulip - three ways to approach it
  • Defined in the design meeting | July 2025
• Problem: dyn compatibility of the proposals
  • Zulip - dyn overview | Nov 2025
• Problem: pinning
  • The Safe Pinned Initialization Problem | Mar 2023
  • Overview: Safe Pinned Initialization | Sep 2022