# Generic Const Args and You

DevFeed: [Generic Const Args and You](<https://devfeed.tech/articles/generic-const-args-and-you-63726.md>)

Original publisher: [Read original article](<https://blog.rust-lang.org/inside-rust/2026/10/02/generic-const-args-and-you/>)

Author: BoxyUwU

Published: 2026-10-02T00:00:00Z

Content type: tutorial

Language: en

Sources: [Inside Rust Blog](<https://devfeed.tech/sources/inside-rust-blog.md>)

Topics: [Python](<https://devfeed.tech/topics/python.md>), [generic programming](<https://devfeed.tech/topics/generic-programming.md>)

Tags: [code](<https://devfeed.tech/tags/code.md>), [generics](<https://devfeed.tech/tags/generics.md>), [implementation](<https://devfeed.tech/tags/implementation.md>)

## AI overview

The post explains Rust's Generic Const Arguments feature family, which aims to replace `generic_const_exprs` and allow more expressions involving generic parameters in const generics. It describes the feature gates, current restrictions, and experimental macroless syntax, noting that the features are not ready for stabilization.

## Source excerpt

Generic Const Args and You Back in June of 2024 at RustFest Zürich, the Const Generics project group first discussed a new design for supporting more complex uses of generic parameters in Const Generics. Since then, we've continued to refine the initial design and have implemented the new design as a family of features dubbed "Generic Const Arguments" (GCA for short). These features are intended to replace the existing generic_const_exprs feature which has existed in some form or another since min_const_generics was stabilized back in 2021. Even though GCA obviates generic_const_exprs it was still incredibly valuable to have invested the time into it that we did as the design and implementation of GCA was informed quite significantly by generic_const_exprs. Each feature in the GCA family introduces support for a specific set of expressions to be used in Const Generics with generic parameters. This post will go over all of the features part of the GCA family and explain their design and how to use them. A huge thanks to @camelid for doing almost all of the initial implementation work for the GCA prototype. Without him GCA would have stayed just a vague concept rather than anything tangible. Additionally, a huge thanks to @khyperia who has done a significant amount of the implementation and design work required to go from the original GCA prototype to the fully featured family that it is now. Finally there have been a tonne of other people who have made contributions to getting GCA to where it is today. For a full list of everyone and all of their contributions, see the Full Const Generics project goal. What is GCA On stable, only generic parameters by themselves (e.g. { N }) or fully concrete constants (e.g. { 1 + 1 }) are supported by Const Generics. It's not possible to have arrays like [u8; T::NUM_BYTES] or [u8; N + 1]. This limitation prevents a lot of useful abstractions and pushes users to rely on the typenum crate instead. Generic Const Arguments is a family o