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cmd/compile: generic function appears to use incorrect type descriptor #52026

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QuantumGhost opened this issue Mar 30, 2022 · 7 comments
Closed

cmd/compile: generic function appears to use incorrect type descriptor #52026

QuantumGhost opened this issue Mar 30, 2022 · 7 comments
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@QuantumGhost
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@QuantumGhost QuantumGhost commented Mar 30, 2022

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

$ go version
go version go1.18 darwin/arm64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE="on"
GOARCH="arm64"
GOBIN=""
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOOS="darwin"
GOPROXY="https://goproxy.io,https://mirrors.aliyun.com/goproxy/"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/yv/fd8s2yw54cldnj29jx3qxrh80000gn/T/go-build4280234465=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Go 2 Playground Link

What did you expect to see?

Type assertion to None returns true.
Type Switch prints s is a None.

What did you see instead?

Type assertion to None returned false.
Type Switch prints oops.

@ianlancetaylor ianlancetaylor changed the title affected/package: core language cmd/compile: generic function appears to use incorrect type descriptor Mar 30, 2022
@ianlancetaylor ianlancetaylor added NeedsInvestigation release-blocker labels Mar 30, 2022
@ianlancetaylor ianlancetaylor added this to the Go1.19 milestone Mar 30, 2022
@ianlancetaylor
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@ianlancetaylor ianlancetaylor commented Mar 30, 2022

CC @randall77 @mdempsky

@kraleva
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@kraleva kraleva commented Mar 30, 2022

Since you are returning a generic type from your returnOption function, go would expect None to be generic as well. If you do change it to None[T], it seems to work for me :) At least that is a possible solution to the problem.

@go101
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@go101 go101 commented Mar 30, 2022

It is really a bug.

It looks the problem is gone if the line s = returnOption[int](0) is changed to s = returnOption[string](0).

@ii64
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@ii64 ii64 commented Apr 2, 2022

https://gotipplay.golang.org/p/p-xVGVKSW10

switch (any)(s).(type) {

@gopherbot
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@gopherbot gopherbot commented Apr 19, 2022

Change https://go.dev/cl/401034 mentions this issue: cmd/compile: use dictionary to convert type to shaped interface type

@randall77
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@randall77 randall77 commented May 3, 2022

@gopherbot please open a backport issue for 1.18.

@gopherbot
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@gopherbot gopherbot commented May 3, 2022

Backport issue(s) opened: #52691 (for 1.18).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

@dmitshur dmitshur added NeedsFix and removed NeedsInvestigation labels May 4, 2022
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