Rc: value -> allocation #65505
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Rc: value -> allocation #65505
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rust-highfive
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Centril
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Oct 17, 2019
We do agree. :) |
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I did a few more edits on And then I did all the same things with |
RalfJung
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Oct 19, 2019
| @@ -1172,6 +1177,8 @@ impl<T: ?Sized + PartialEq> RcEqIdent<T> for Rc<T> { | |||
| /// store large values, that are slow to clone, but also heavy to check for equality, causing this | |||
| /// cost to pay off more easily. It's also more likely to have two `Rc` clones, that point to | |||
| /// the same value, than two `&T`s. | |||
| /// | |||
| /// We can only do this when `T: Eq` as a `PartialEq` might be deliberately irreflexive. | |||
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This is what I concluded after some thinking. It is also in line with this comment by @alexcrichton:
According to Eq's own documentation it signifies the reflexive property (a == a) which I believe means that this is a semantically correct implementation.
So, seems like just a missing comment to me.
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Thanks! @bors r+ rollup |
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📌 Commit 1b38463 has been approved by |
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Rc: value -> allocation See rust-lang#64484. This does not yet edit `Arc` as I first wanted to be sure we agree on the terminology the way it actually ends up. "value" as a term appears a lot in this file, and sometimes it refers to the value stored inside the `RcBox` while sometimes it refers to the `RcBox` itself. I tried to properly tease these apart but may have made some mistakes. The former should now always be called "inner value" and the latter "allocation". One area where I was very unsure of which terminology is dropping: the `value` field of the `RcBox` will get dropped *earlier* than the `RcBox` itself if there are weak references. I decided that "dropping the value stored in the allocation" refers to dropping the value field, while "destroying the allocation" refers to actually freeing its backing memory. r? @Centril
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Rc: value -> allocation See rust-lang#64484. This does not yet edit `Arc` as I first wanted to be sure we agree on the terminology the way it actually ends up. "value" as a term appears a lot in this file, and sometimes it refers to the value stored inside the `RcBox` while sometimes it refers to the `RcBox` itself. I tried to properly tease these apart but may have made some mistakes. The former should now always be called "inner value" and the latter "allocation". One area where I was very unsure of which terminology is dropping: the `value` field of the `RcBox` will get dropped *earlier* than the `RcBox` itself if there are weak references. I decided that "dropping the value stored in the allocation" refers to dropping the value field, while "destroying the allocation" refers to actually freeing its backing memory. r? @Centril
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Oct 19, 2019
Rollup of 5 pull requests Successful merges: - #64007 (Add check for overlapping ranges to unreachable patterns lint) - #65192 (Use structured suggestion for restricting bounds) - #65226 (BTreeSet symmetric_difference & union optimized) - #65448 (rustc_codegen_ssa: remove some unnecessary Box special-casing.) - #65505 (Rc: value -> allocation) Failed merges: r? @ghost
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See #64484. This does not yet edit
Arcas I first wanted to be sure we agree on the terminology the way it actually ends up. "value" as a term appears a lot in this file, and sometimes it refers to the value stored inside theRcBoxwhile sometimes it refers to theRcBoxitself. I tried to properly tease these apart but may have made some mistakes. The former should now always be called "inner value" and the latter "allocation".One area where I was very unsure of which terminology is dropping: the
valuefield of theRcBoxwill get dropped earlier than theRcBoxitself if there are weak references. I decided that "dropping the value stored in the allocation" refers to dropping the value field, while "destroying the allocation" refers to actually freeing its backing memory.r? @Centril