rust-lang / rust-lang/rust-clippy

New lint for redundant clone in `format!`

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#5,142 1 comment 0 reactions 0 assignees View on GitHub

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C-enhancement E-hard
Dominant language
Rust
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Description

If somebody writes format!("foo: {}", foo.clone()) is that always redundant (since format takes a reference to its arguments and then drops them instantly)? Maybe make sure it doesn't trigger on e.g. foo.clone().bar() since that isn't necessarily redundant.

I feel like this is a specific case of cloning an immutable non-owned type that you don't then retain but that'd require proper compiler support.

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Research direction

No files, tests, or entry points are named. Start by reproducing the format!("foo: {}", foo.clone()) case and compare it with a chained expression such as foo.clone().bar(). Done means establishing whether a Clippy lint can safely identify only redundant clones without requiring unresolved compiler support.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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