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Lifetime must be 'static, but why? #138408

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timokoesters opened this issue Mar 12, 2025 · 0 comments
Open

Lifetime must be 'static, but why? #138408

timokoesters opened this issue Mar 12, 2025 · 0 comments
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A-borrow-checker Area: The borrow checker A-diagnostics Area: Messages for errors, warnings, and lints A-lifetimes Area: Lifetimes / regions D-terse Diagnostics: An error or lint that doesn't give enough information about the problem at hand. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@timokoesters
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timokoesters commented Mar 12, 2025 •
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Code

https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=f9243c5a93b40649aaa99f20dc78d5b0

fn input(_: &'static str) {}

fn main() {
    let x = String::new();
    input(&x);
}

Current output

error[E0597]: `x` does not live long enough
 --> src/main.rs:5:11
  |
4 |     let x = String::new();
  |         - binding `x` declared here
5 |     input(&x);
  |     ------^^-
  |     |     |
  |     |     borrowed value does not live long enough
  |     argument requires that `x` is borrowed for `'static`
6 | }
  | - `x` dropped here while still borrowed

For more information about this error, try `rustc --explain E0597`.

Desired output

Maybe something like

hint: lifetime must be 'static to satisfy function
fn input(_: &'static str) {}

Rationale and extra context

In the example above it is also easy to figure it out yourself, but I ran into a case where the actual function is hidden:
https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=4c1003f809e67aec7ded5ea736ab0430
pub fn body<T: Into<Body>>(mut self, body: T) -> RequestBuilder
impl From<&'static str> for Body

In this case the message should directly point to the from implementation.

Rust Version

I tried this on the Rust playground on Rust 1.85.0
@timokoesters timokoesters added A-diagnostics Area: Messages for errors, warnings, and lints T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Mar 12, 2025
@fmease fmease added A-lifetimes Area: Lifetimes / regions D-terse Diagnostics: An error or lint that doesn't give enough information about the problem at hand. A-borrow-checker Area: The borrow checker labels Mar 12, 2025
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A-borrow-checker Area: The borrow checker A-diagnostics Area: Messages for errors, warnings, and lints A-lifetimes Area: Lifetimes / regions D-terse Diagnostics: An error or lint that doesn't give enough information about the problem at hand. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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@fmease @timokoesters