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cmd/compile: panic on generic type switch #48838

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qmuntal opened this issue Oct 7, 2021 · 2 comments
Closed

cmd/compile: panic on generic type switch #48838

qmuntal opened this issue Oct 7, 2021 · 2 comments
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@qmuntal
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@qmuntal qmuntal commented Oct 7, 2021

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

go version devel go1.18-6f74ed06c5 Thu Oct 7 03:41:40 2021 +0000 windows/amd64

Does this issue reproduce with the latest release?

Only in tip

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

go env Output
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\muntal\AppData\Local\go-build
set GOENV=C:\Users\muntal\AppData\Roaming\go\env  
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\muntal\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\muntal\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Users\muntal\sdk\gotip
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=C:\Users\muntal\sdk\gotip\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=devel go1.18-6f74ed06c5 Thu Oct 7 03:41:40 2021 +0000
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=C:\_\stateless\go.mod
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\muntal\AppData\Local\Temp\go-build2096857021=/tmp/go-build -gno-record-gcc-switches 

What did you do?

Crafted this minimal reproducer from a much complex code base.

== main.go ==

package main

func main() {
  check[string]()
}

func check[T any]() {
  var result setter[T]
  switch result.(type) {
  case fooA[T]:
  case fooB[T]:
  }
}

type setter[T any] interface {
  Set(T)
}

type fooA[T any] struct{}

func (fooA[T]) Set(T) {}

type fooB[T any] struct{}

func (fooB[T]) Set(T) {}

gotip tool compile main.go

What did you expect to see?

Successful compilation

What did you see instead?

panic: runtime error: index out of range [1] with length 1

goroutine 1 [running]:
cmd/compile/internal/noder.(*irgen).dictPass.func1({0x14c6920, 0xc0003f9020})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1302 +0x100b
cmd/compile/internal/ir.editCaseClauses({0xc00005d140, 0x2, 0x14c7e38}, 0xc00041a9a0)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1449 +0x62
cmd/compile/internal/ir.(*SwitchStmt).editChildren(0xc000134b00, 0xc00041a9a0)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1320 +0xb4
cmd/compile/internal/ir.EditChildren(...)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/visit.go:185
cmd/compile/internal/noder.(*irgen).dictPass.func1({0x14c8b80, 0xc000134b00})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1185 +0x74
cmd/compile/internal/ir.editNodes({0xc0003feff0, 0x3, 0x0}, 0xc00041a9a0)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1521 +0x74
cmd/compile/internal/ir.(*Func).editChildren(0xa7b267, 0x10)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/func.go:153 +0x2e
cmd/compile/internal/ir.EditChildren(...)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/visit.go:185
cmd/compile/internal/noder.(*irgen).dictPass.func1({0x14c71b8, 0xc0003f4c60})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1185 +0x74
cmd/compile/internal/noder.(*irgen).dictPass(0xc000404000, 0xc00040e150)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1319 +0x126
cmd/compile/internal/noder.(*irgen).stencil(0xc000404000)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:240 +0x51b
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/irgen.go:307 +0x359
cmd/compile/internal/noder.check2({0xc000006448, 0x1, 0x1})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/irgen.go:93 +0x175
cmd/compile/internal/noder.LoadPackage({0xc00005e3d0, 0x1, 0x0})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/noder.go:90 +0x335
cmd/compile/internal/gc.Main(0x13934c8)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/gc/main.go:190 +0xaf3
main.main()
        C:/Users/muntal/sdk/gotip/src/cmd/compile/main.go:55 +0xdd
PS C:\_\stateless> gotip tool compile main.go        
panic: runtime error: index out of range [1] with length 1

goroutine 1 [running]:
cmd/compile/internal/noder.(*irgen).dictPass.func1({0x14c6920, 0xc0003f9020})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1302 +0x100b
cmd/compile/internal/ir.editCaseClauses({0xc00005d160, 0x2, 0x14c7e38}, 0xc00041a9a0)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1449 +0x62
cmd/compile/internal/ir.(*SwitchStmt).editChildren(0xc000134b00, 0xc00041a9a0)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1320 +0xb4
cmd/compile/internal/ir.EditChildren(...)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/visit.go:185
cmd/compile/internal/noder.(*irgen).dictPass.func1({0x14c8b80, 0xc000134b00})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1185 +0x74
cmd/compile/internal/ir.editNodes({0xc0003feff0, 0x3, 0x0}, 0xc00041a9a0)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1521 +0x74
cmd/compile/internal/ir.(*Func).editChildren(0xa7b267, 0x10)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/func.go:153 +0x2e
cmd/compile/internal/ir.EditChildren(...)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/ir/visit.go:185
cmd/compile/internal/noder.(*irgen).dictPass.func1({0x14c71b8, 0xc0003f4c60})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1185 +0x74
cmd/compile/internal/noder.(*irgen).dictPass(0xc000400000, 0xc00040e180)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:1319 +0x126
cmd/compile/internal/noder.(*irgen).stencil(0xc000400000)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/stencil.go:240 +0x51b
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/irgen.go:307 +0x359
cmd/compile/internal/noder.LoadPackage({0xc00005e3d0, 0x1, 0x0})
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/noder/noder.go:90 +0x335
cmd/compile/internal/gc.Main(0x13934c8)
        C:/Users/muntal/sdk/gotip/src/cmd/compile/internal/gc/main.go:190 +0xaf3
main.main()
        C:/Users/muntal/sdk/gotip/src/cmd/compile/main.go:55 +0xdd

@cuonglm @griesemer

@cuonglm
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@cuonglm cuonglm commented Oct 7, 2021

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@cuonglm cuonglm added this to the Go1.18 milestone Oct 7, 2021
@gopherbot
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@gopherbot gopherbot commented Oct 7, 2021

Change https://golang.org/cl/354549 mentions this issue: cmd/compile: fix the index variable is shadowed in dictPass

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@gopherbot gopherbot closed this in be571a3 Oct 7, 2021
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