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PartialEq: PERs are homogeneous #104912

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merged 1 commit into from
Dec 6, 2022
Merged

PartialEq: PERs are homogeneous #104912

merged 1 commit into from
Dec 6, 2022

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RalfJung
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PartialEq claims that it corresponds to a PER, but that is only a well-defined statement when Rhs == Self. There is no standard notion of PER on a relation between two different sets/types. So move this out of the first paragraph and clarify this.

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rustbot commented Nov 25, 2022

r? @Mark-Simulacrum

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Nov 25, 2022
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rustbot commented Nov 25, 2022

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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@bors r+ rollup

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bors commented Dec 5, 2022

📌 Commit 34de257 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 5, 2022
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Dec 5, 2022
@matthiaskrgr
Rollup merge of rust-lang#104912 - RalfJung:per, r=Mark-Simulacrum
9ad58d0 
PartialEq: PERs are homogeneous

PartialEq claims that it corresponds to a PER, but that is only a well-defined statement when `Rhs == Self`. There is no standard notion of PER on a relation between two different sets/types. So move this out of the first paragraph and clarify this.
@matthiaskrgr matthiaskrgr mentioned this pull request Dec 5, 2022
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@matthiaskrgr matthiaskrgr mentioned this pull request Dec 5, 2022
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bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 5, 2022
@bors
Auto merge of rust-lang#105328 - matthiaskrgr:rollup-qnfksmq, r=matth…
8e440b0 
…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#104912 (PartialEq: PERs are homogeneous)
 - rust-lang#104952 (Streamline the user experience for `x.py setup`)
 - rust-lang#104953 (Ensure required submodules at the same time as updating existing submodules)
 - rust-lang#105180 (Use proper HirId for async track_caller attribute check)
 - rust-lang#105222 (std update libc version and freebsd image build dependencies)
 - rust-lang#105223 (suggest parenthesis around ExprWithBlock BinOp ExprWithBlock)
 - rust-lang#105230 (Skip recording resolution for duplicated generic params.)
 - rust-lang#105301 (update Miri)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 8ad447c into rust-lang:master Dec 6, 2022
@rustbot rustbot added this to the 1.67.0 milestone Dec 6, 2022
@JanBeh JanBeh mentioned this pull request Dec 6, 2022
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JanBeh commented Dec 6, 2022

I would like to note that an "equality comparison" (in the mathematical sense) viewed as a relation is always an equivalence relation and thus also a partial equality comparison (PER). In terms of computer science, however, equality comparisons aren't necessarily the same as equality comparisons in mathematics. Nonetheless, this can be a bit confusing and this PR still describes PartialEq as "equality comparison".

I also think the term "partial equality" is misleading (which was also already used prior to this PR).

See PR #103046 for an attempt to fix these issues.

@RalfJung RalfJung deleted the per branch December 8, 2022 21:36
Aaron1011 pushed a commit to Aaron1011/rust that referenced this pull request Jan 6, 2023
@matthiaskrgr
Rollup merge of rust-lang#104912 - RalfJung:per, r=Mark-Simulacrum
6b1bcf0 
PartialEq: PERs are homogeneous

PartialEq claims that it corresponds to a PER, but that is only a well-defined statement when `Rhs == Self`. There is no standard notion of PER on a relation between two different sets/types. So move this out of the first paragraph and clarify this.
Aaron1011 pushed a commit to Aaron1011/rust that referenced this pull request Jan 6, 2023
@bors
Auto merge of rust-lang#105328 - matthiaskrgr:rollup-qnfksmq, r=matth…
d35ad1a 
…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#104912 (PartialEq: PERs are homogeneous)
 - rust-lang#104952 (Streamline the user experience for `x.py setup`)
 - rust-lang#104953 (Ensure required submodules at the same time as updating existing submodules)
 - rust-lang#105180 (Use proper HirId for async track_caller attribute check)
 - rust-lang#105222 (std update libc version and freebsd image build dependencies)
 - rust-lang#105223 (suggest parenthesis around ExprWithBlock BinOp ExprWithBlock)
 - rust-lang#105230 (Skip recording resolution for duplicated generic params.)
 - rust-lang#105301 (update Miri)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
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