Make ops::DerefMut a diagnostic item
#147643
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@relaxcn Why would it be a good idea to allow such calls in Deref(Mut) impls? |
Reference to rust-lang/rust-clippy#15392, I think it is make sense to me. |
| /// *x = 'b'; | ||
| /// assert_eq!('b', x.value); | ||
| /// ``` | ||
| #[lang = "deref_mut"] |
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DerefMut already has a lang item, can you use LangItem::DeferMut instead?
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Of course. I can use it to archive the same goal.
But strangely enough, Deref is both a language item and a diagnostic item:
rust/library/core/src/ops/deref.rs
Lines 133 to 139 in 4b94758
Why not the DerefMut to be a diagnostic item? Then we can use them uniformly like:
[sym::Deref, sym::DerefMut]
.iter()
.any(|&sym| cx.tcx.is_diagnostic_item(sym, trait_id))
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this feels like a reason to remove the Deref diagnostics item as well 😆
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😂 I'm just confused about it.
Is it bad to use diagnostics item?
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no worries
I am actually not quite sure. Our general approach is to use lang_items instead of diagnostics items if they already exist.
I don't think there's a large reason for that and we may even want is_diagnostics_item to also just lookup lang items 😁 actually, I think that would be a good improvement
The main reason seems to be "there should only be one consistent way to do things"
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Thank you for your explanation.
So I will close this PR.
BTW it will have a big influence if we remove Deref diagnostics item because rust-clippy use it.
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we have clippy as a subtree, so we can update it in the same PR
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All right. Thank you.
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I'm working on an enhancement to clippy::explicit_deref_methods, which would allow explicit
dereforderef_mutmethod calls in implementation of the theDereforDerefMuttrait, so I need aDerefMutdiagnostic item to check if we are already in the impl ofDerefMuttrait.