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lint type &Option<&T> #1377

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oli-obk opened this issue Dec 6, 2016 · 4 comments
Closed

lint type &Option<&T> #1377

oli-obk opened this issue Dec 6, 2016 · 4 comments
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A-lint Area: New lints good-first-issue These issues are a good way to get started with Clippy L-unnecessary Lint: Warn about unnecessary code T-middle Type: Probably requires verifiying types

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@oli-obk
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oli-obk commented Dec 6, 2016

since & is Copy, just suggest to use Option<&T>
@oli-obk oli-obk added L-unnecessary Lint: Warn about unnecessary code good-first-issue These issues are a good way to get started with Clippy A-lint Area: New lints T-middle Type: Probably requires verifiying types labels Dec 6, 2016
@clarfonthey
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clarfonthey commented Dec 8, 2016 •
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This applies to &mut Option<&mut T> too, because as_ref and as_mut exist. Ditto for Result.

@shepmaster
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This applies to &mut Option<&mut T> too

Does it though? With a &mut Option<T>, I could mem::replace or mem::swap it with a completely different option, or call Option::take on it, which does the same thing internally.

@clarfonthey
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@shepmaster I think you misunderstood; &mut Option<&mut T> should be written as Option<&mut T>, not &mut Option<T>. This is very similar to writing &&T instead of &T.

@Manishearth
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I think you misunderstood; &mut Option<&mut T> should be written as Option<&mut T>, not &mut Option.

@shepmaster's comment still applies. You cannot set the shared Option to None with Option<&mut T>

@dvermd dvermd mentioned this issue Oct 12, 2020
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bors added a commit that referenced this issue Nov 3, 2020
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Auto merge of #6165 - dvermd:ref_option_ref, r=flip1995
2fe87a8 
Add lint 'ref_option_ref' #1377

This lint checks for usage of `&Option<&T>` which can be simplified as `Option<&T>` as suggested in #1377.

This WIP PR is here to get feedback on the lint as there's more cases to be handled:
* statics/consts,
* associated types,
* type alias,
* function/method parameter/return,
* ADT definitions (struct/tuple struct fields, enum variants)

changelog: Add 'ref_option_ref' lint
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A-lint Area: New lints good-first-issue These issues are a good way to get started with Clippy L-unnecessary Lint: Warn about unnecessary code T-middle Type: Probably requires verifiying types
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@shepmaster @oli-obk @Manishearth @camsteffen @clarfonthey