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Tracking Issue for the use of ? in constants #74935
Description
The ? operator expands to invoking Try::into_result for the argument and Into::into for the error of the result. In order to support these, we need to
- Figure out traits-in-const: Tracking Issue for removing
impl constand~constin the standard library #110395 - stabilize
impl const Trait for Typeitems Tracking Issue for RFC 3762, "Make trait methods callable in const contexts" #143874 - implement
const TryforResultandOptionin libstd Constify Try, From, TryFrom and relevant traits #143768
Reacted by Michael Pfaff, Bob, Sedat Kapanoğlu, José Luis Cruz, John T. Wodder II, Brandon, AMS21, woojiq, Barrett Ray, orzogc and 7 more
Reacted by Gabriel Bjørnager Jensen and Farès Chati
Activity
a1phyr commentedon Jul 30, 2020
#60964 also needs to be resolved to be able to implement
const Try.See https://play.rust-lang.org/?version=nightly&gist=bdf8f8e2774f54c084e2cb25624ce193
jhpratt commentedon Mar 1, 2022
oli-obk commentedon Mar 1, 2022
jhpratt commentedon Mar 1, 2022
oli-obk commentedon Mar 1, 2022
jhpratt commentedon Mar 1, 2022
Merge #3605: Mark function as const
clarfonthey commentedon Jul 22, 2025
Poking around, it's very confusing that this tracking issue isn't just for the traits related to
?, but also includesAsRef,AsMut,TryFrom, andTryInto. I would expect those traits and their impls to go under #143773, and for this to be reserved for justTry,FromResidual, andResidual.EDIT: I've done this under #144289.
Rollup merge of rust-lang#146088 - npmccallum:try, r=scottmcm
Unrolled build for #146088
Rollup merge of rust-lang#146088 - npmccallum:try, r=scottmcm
programmerjake commentedon Sep 26, 2025
experience report from my demo of how we could constify array
try_map:https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&gist=23947d4625bdbe04c77cbacb64589f47
we should change the trait bounds on
Residual::TryTypeto[const] Tryand maybe add[const] Destructbounds.clarfonthey commentedon Sep 27, 2025
Yeah,
Residual::TryTypenot being[const] Tryis definitely a mistake. I figure you're going to make a PR for it, but if not, I can instead.programmerjake commentedon Sep 27, 2025
@clarfonthey feel free to make a PR
Rollup merge of #146088 - npmccallum:try, r=scottmcm
Rollup merge of rust-lang#146088 - npmccallum:try, r=scottmcm