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reflect: Type interface is unimplemented comparable (generics) #51179

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Code-Hex opened this issue Feb 14, 2022 · 7 comments
Closed

reflect: Type interface is unimplemented comparable (generics) #51179

Code-Hex opened this issue Feb 14, 2022 · 7 comments
Labels
compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge generics Issue is related to generics NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Milestone
Go1.20

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@Code-Hex
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Code-Hex commented Feb 14, 2022 •
edited

What version of Go are you using (go version)?

$ gotip version
go version devel go1.18-e50f0f372b Fri Feb 11 05:11:58 2022 +0000 darwin/arm64

What did you do?

The document for reflect.Type interface has described is comparable.

Type values are comparable, such as with the == operator, so they can be used as map keys.

However, I tried to compare with a function using generics comparable, and I get a compilation error.

What did you expect to see?

compilable

What did you see instead?

compilation error.

https://go.dev/play/p/vPcBpD86rST?v=gotip
@hopehook
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hopehook commented Feb 14, 2022 •
edited

I find it is work fine at the my local go source code, which is failed on the go playground.

  • my local version success: go version devel go1.18-a991d9dc27 Thu Jan 27 05:30:27 2022 +0000 darwin/amd64
  • playground version failed: devel go1.18-5bd734839d Sun Feb 13 02:11:11 2022 +0000

So i compiled a new one, it failed also.

  • latest source code of master branch failed: go version devel go1.18-badbc52d82 Mon Feb 14 05:18:03 2022 +0000 darwin/amd64

@hopehook
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@griesemer

@dmitshur
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dmitshur commented Feb 14, 2022 •
edited

Also CC @findleyr.

Placing it in 1.18 milestone to at least investigate whether something about this needs to be done for 1.18.

@dmitshur dmitshur added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Feb 14, 2022
@dmitshur dmitshur added this to the Go1.18 milestone Feb 14, 2022
@ianlancetaylor
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It's true that reflect.Type is not treated as a comparable type, and it's true that that may be problematic in some cases. That said, we aren't going to do anything here for 1.18.

@ianlancetaylor ianlancetaylor modified the milestones: Go1.18, Go1.19 Feb 14, 2022
@twmb twmb mentioned this issue Apr 10, 2022
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@ianlancetaylor
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See discussion at #51338 for a way to fix this.

@ianlancetaylor ianlancetaylor modified the milestones: Go1.19, Go1.20 Jun 24, 2022
@ianlancetaylor
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Rolling forward to 1.20.

@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Jul 7, 2022
@ianlancetaylor
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Closing in favor of #56548 which attempts to address the general issue.

@ianlancetaylor ianlancetaylor closed this as not planned Won't fix, can't repro, duplicate, stale Nov 4, 2022
@ianlancetaylor ianlancetaylor added the generics Issue is related to generics label Nov 4, 2022
@golang golang locked and limited conversation to collaborators Nov 4, 2023
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Labels
compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge generics Issue is related to generics NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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Release Status & Release Blockers
Status: Done
Milestone
Go1.20
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@dmitshur @ianlancetaylor @Code-Hex @hopehook @gopherbot