rust-lang / rust-lang/rfcs

Lifetime elision in trait constraints

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Description

Originally from https://github.com/rust-lang/rust/issues/13840:

This compiles:

fn isum<'a, I: Iterator<&'a i32>>(mut it: I) -> int { it.fold(0, |a, b| a + *b) }

This should be the same, but doesn't compile:

fn isum<I: Iterator<&i32>>(mut it: I) -> i32 { it.fold(0, |a, b| a + *b)}

The compiler complains of a "missing lifetime specifier" at the &int.

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  3. Fork the repository and make your change on a branch.
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Research direction

Start by reading the linked rust-lang/rust issue 13840 and comparing the two Iterator constraint examples in this issue. Determine the intended lifetime-elision behavior and how it should be specified and validated; the payload names no implementation files or tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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