Tracking Issue for int_from_ascii

Feature gate: #![feature(int_from_ascii)]

This is a tracking issue for int_from_ascii, providing equivalent methods to {usize,u8,u16,u32,u64,u128,isize,i8,i16,i32,i64,i128}::from_str() and from_str_radix() that allow working directly on byte slices, in order to skip UTF-8 validation.

Public API

For each integer type X (usize, u8, u16, u32, u64, u128, isize, i8, i16, i32, i64, i128):

// core::num

impl X {
    pub const fn from_ascii_bytes<T>(src: T) -> Result<X, ParseIntError>
    where
        T: [const] AsRef<[u8]> + [const] core::marker::Destruct;

    pub const fn from_ascii_bytes_radix<T>(src: T, radix: u32) -> Result<X, ParseIntError>
    where
        T: [const] AsRef<[u8]> + [const] core::marker::Destruct;
}

impl NonZero<X> {
    pub const fn from_ascii_bytes<T>(src: T) -> Result<Self, ParseIntError>
    where
        T: [const] AsRef<[u8]> + [const] core::marker::Destruct;

    pub const fn from_ascii_bytes_radix<T>(src: T, radix: u32) -> Result<Self, ParseIntError>
    where
        T: [const] AsRef<[u8]> + [const] core::marker::Destruct;
}

Originally with src: &[u8]

// core::num

impl X {
    pub const fn from_ascii(src: &[u8]) -> Result<X, ParseIntError>;
    pub const fn from_ascii_radix(src: &[u8], radix: u32) -> Result<X, ParseIntError>;
}

impl NonZero<X> {
    pub const fn from_ascii(src: &[u8]) -> Result<Self, ParseIntError>;
    pub const fn from_ascii_radix(src: &[u8], radix: u32) -> Result<Self, ParseIntError>;
}

Steps / History

Abandoned implementation: Implement int_from_ascii_radix #105206
API change proposal: Add from_bytes_radix function libs-team#469
Implementation for T: Implement int_from_ascii (#134821) #134824
Implementation for NonZero<T>: feat: Implement int_from_ascii for NonZero<T> #152267
from_ascii -> from_ascii_bytes and src: &[u8] -> src: impl AsRef<[u8]>: feat: Update method signature of int_from_ascii #159554
Stabilization PR: Stabilize int_from_ascii #163696

Unresolved Questions

Stabilize Tracking Issue for nonzero_from_str_radix #152193 first

Opened PR #134824 with an implementation.

Implement `int_from_ascii` (rust-lang#134821)

Auto merge of rust-lang#134824 - niklasf:int_from_ascii, r=<try>

Auto merge of rust-lang#134824 - niklasf:int_from_ascii, r=ibraheemdev

Implement `int_from_ascii` (rust-lang#134821)

Squashed 'library/' changes from 78fc550..b522de4

Implement `int_from_ascii` (rust-lang#134821)

Squashed 'library/' changes from 78fc550..b522de4

Implement `int_from_ascii` (rust-lang#134821)

Squashed 'library/' changes from 78fc550..0b9e7db

@niklasf

@niklasf Could you please update #134821 (comment) after #152267 is merged?

The current version only mentions primitive integer types, so I think the beginning description, the Public API section, and the Steps / History section should be updated.

Examples:

// core::num

impl NonZero<T> {
    pub const fn from_ascii(src: &[u8]) -> Result<Self, ParseIntError>;
    pub const fn from_ascii_radix(src: &[u8], radix: u32) -> Result<Self, ParseIntError>;
}

Thanks. I think that means #152193 should be stabilized first, so we don't end up with NonZero<T>::from_ascii_radix() without a matching NonZero<T>::from_str_radix().

Rollup merge of rust-lang#152267 - sorairolake:feature/nonzero-from-a…

Unrolled build for #152267

nonzero_from_str_radix was stabilized.
Is it time to FCP this?

Well I raised this one on Zulip and the discussion there suggested changing the API to:

impl X {
    pub const fn from_ascii_bytes<T>(src: T) -> Result<X, ParseIntError>
    where
        T: [const] AsRef<[u8]> + [const] core::marker::Destruct;

    pub const fn from_ascii_bytes_radix<T>(src: T, radix: u32) -> Result<X, ParseIntError>
    where
        T: [const] AsRef<[u8]> + [const] core::marker::Destruct;
}

So have raised #159554 to implement that.

Rollup merge of rust-lang#159554 - ajtribick:int_from_ascii_bytes, r=…

Unrolled build for #159554

Rollup merge of #159554 - ajtribick:int_from_ascii_bytes, r=Mark-Simu…

If this feature is stabilized, I think it would be good to add a lint check for cases where &str is passed as a parameter corresponding to these methods in Clippy.

let x = u8::from_ascii_bytes("+10");
let y = NonZero::<i32>::from_ascii_bytes_radix("A", 16);

Could be written as:

let x = u8::from_str("+10");
let y = NonZero::<i32>::from_str_radix("A", 16);

I don't know how much evidence is needed for the "experience" part of the stabilisation report, but I can verify that it works for the parser application I want to use it for. Minimal example: https://github.com/ajtribick/int_from_ascii_test

I would actually also need floating point versions of these functions ("float_from_ascii") but I don't think it makes sense to start work on those before stabilising this feature.

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Tracking Issue for int_from_ascii #134821

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niklasf commented on Dec 27, 2024

91 remaining items

sorairolake commented on Feb 7, 2026

niklasf commented on Feb 7, 2026

dimpolo commented on Jun 24, 2026

ajtribick commented on Jul 20, 2026

sorairolake commented on Sep 3, 2026

ajtribick commented on Sep 22, 2026

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Tracking Issue for `int_from_ascii` #134821