Stabilize const `{integer}::from_str_radix` i.e. `const_int_from_str`
This PR stabilizes the feature `const_int_from_str`.
- ACP Issue: rust-lang/libs-team#74
- Implementation PR: rust-lang/rust#99322
- Part of Tracking Issue: rust-lang/rust#59133
API Change Diff:
```diff
impl {integer} {
- pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError>;
+ pub const fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError>;
}
impl ParseIntError {
- pub fn kind(&self) -> &IntErrorKind;
+ pub const fn kind(&self) -> &IntErrorKind;
}
```
This makes it easier to parse integers at compile-time, e.g.
the example from the Tracking Issue:
```rust
env!("SOMETHING").parse::<usize>().unwrap()
```
could now be achived with
```rust
match usize::from_str_radix(env!("SOMETHING"), 10) {
Ok(val) => val,
Err(err) => panic!("Invalid value for SOMETHING environment variable."),
}
```
rather than having to depend on a library that implements or manually implement the parsing at compile-time.
---
Checklist based on [Libs Stabilization Guide - When there's const involved](https://std-dev-guide.rust-lang.org/development/stabilization.html#when-theres-const-involved)
I am treating this as a [partial stabilization](https://std-dev-guide.rust-lang.org/development/stabilization.html#partial-stabilizations) as it shares a tracking issue (and is rather small), so directly opening the partial stabilization PR for the subset (feature `const_int_from_str`) being stabilized.
- [x] ping Constant Evaluation WG
- [x] no unsafe involved
- [x] no `#[allow_internal_unstable]`
- [ ] usage of `intrinsic::const_eval_select` rust-lang/rust#124625 in `from_str_radix_assert` to change the error message between compile-time and run-time
- [ ] [rust-labg/libs-api FCP](https://github.com/rust-lang/rust/pull/124941#issuecomment-2207021921)
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