rust-lang / rust-lang/rust

Effective breakage to `jiff` due to `ambiguous_negative_literals`

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C-discussion I-lang-radar T-lang
Dominant language
Rust
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Description

We should discuss this bit of evidence that came in after the FCP completed on:

@BurntSushi said:

This completely broke Jiff once the change landed. Because it specifically supports negating spans like -1.hour(). In the case of Jiff, there is no ambiguity because -1.hour() and (-1).hour() and -(1.hour()) are all precisely equivalent.

cc @BurntSushi @rust-lang/lang

@rustbot labels +T-lang +I-lang-nominated

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Research direction

Start by reading Rust pull request #121364 and the linked discussion about ambiguous_negative_literals, then review the cited Jiff negative-spans documentation. The issue currently asks for discussion of the breakage rather than naming a specific code change or test, so the desired outcome is not defined.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Quiet
Clarity
Needs clarification
Newbie friendliness
25/100

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