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cmd/compile: "internal compiler error: is not shape-identical" crash #66663

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ipfreely-uk opened this issue Apr 3, 2024 · 3 comments
Open

cmd/compile: "internal compiler error: is not shape-identical" crash #66663

ipfreely-uk opened this issue Apr 3, 2024 · 3 comments
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@cuonglm
Labels
compiler/runtime Issues related to the Go compiler and/or runtime. NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Milestone
Go1.23

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@ipfreely-uk
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Go version

go version go1.22.1 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/ipfreely/.cache/go-build'
GOENV='/home/ipfreely/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/ipfreely/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/ipfreely/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/go1.22.1'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/opt/go1.22.1/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.22.1'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/ipfreely/projects/gobug/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3230307039=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Experimenting with limits of the generic type system. Error triggered by addition of Blocks() to Range interface.

// go.mod
module example.com/bug/v2

go 1.22.1
// bug.go
package gobug

type Iterator[A any] func() (bool, A)

type Set[A any] interface {
	Addresses() Iterator[A]
	Ranges() Iterator[Range[A]]
}

type Range[A any] interface {
	Set[A]
	// Problem line
	Blocks() Iterator[Block[A]]
}

type Block[A any] interface {
	Range[A]
}

type rangeImpl[A any] struct{}

func (r *rangeImpl[A]) Addresses() Iterator[A] {
	return func() (bool, A) {
		var a A
		return false, a
	}
}

func (r *rangeImpl[A]) Ranges() Iterator[Range[A]] {
	return func() (bool, Range[A]) {
		var a Range[A]
		return false, a
	}
}

func (r *rangeImpl[A]) Blocks() Iterator[Block[A]] {
	return func() (bool, Block[A]) {
		var a Block[A]
		return false, a
	}
}

func NewRange[A any]() Range[A] {
	return &rangeImpl[A]{}
}
// bug_test.go
package gobug_test

import (
	"testing"

	gobug "example.com/bug/v2"
)

func TestNetRange(t *testing.T) {
	type AddrImpl struct{}
	r := gobug.NewRange[AddrImpl]()
	if r == nil {
		t.Fail()
	}
}

What did you see happen?

Internal compile error running go test

$ go test example.com/bug/v2
# example.com/bug/v2_test [example.com/bug/v2.test]
./bug_test.go:11:31: internal compiler error: gobug.NewRange[go.shape.struct {}](&gobug..dict.NewRange[example.com/bug/v2_test.AddrImpl·1]) (type gobug.Range[go.shape.struct {}]) is not shape-identical to gobug.Range[example.com/bug/v2_test.AddrImpl·1]

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new
FAIL	example.com/bug/v2 [build failed]
FAIL

What did you expect to see?

Expected code to compile or compiler to emit error saying what is illegal about the code.
@ALTree ALTree changed the title go test: internal compiler error: gobug.NewRange[go.shape.struct {}](&gobug..dict.NewRange[example.com/bug/v2_test.AddrImpl·1]) (type gobug.Range[go.shape.struct {}]) is not shape-identical to gobug.Range[example.com/bug/v2_test.AddrImpl·1] cmd/compile: "internal compiler error: is not shape-identical" crash Apr 3, 2024
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Apr 3, 2024
@ALTree
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ALTree commented Apr 3, 2024

Reproducible on tip too.

@ALTree ALTree added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Apr 3, 2024
@ALTree ALTree added this to the Go1.23 milestone Apr 3, 2024
@cuonglm
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cuonglm commented Apr 3, 2024

Simpler reproducer:

package p

type Iterator[A any] func() (bool, A)

type Range[A any] interface {
	Blocks() Iterator[Block[A]]
}

type Block[A any] interface {
	Range[A]
}

type rangeImpl[A any] struct{}

func (r *rangeImpl[A]) Blocks() Iterator[Block[A]] {
	return func() (bool, Block[A]) {
		var a Block[A]
		return false, a
	}
}

func NewRange[A any]() Range[A] {
	return &rangeImpl[A]{}
}

type AddrImpl struct{}

var _ = NewRange[AddrImpl]()

I think this has the same underlying problem with #65362, https://go-review.googlesource.com/c/go/+/559656 would fix this.

@gopherbot
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Change https://go.dev/cl/559656 mentions this issue: cmd/compile: fix recursive generic interface instantiation

ipfreely-uk pushed a commit to ipfreely-uk/go that referenced this issue Apr 3, 2024
Workaround for golang/go#66663
b881be6
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Assignees

@cuonglm cuonglm

Labels
compiler/runtime Issues related to the Go compiler and/or runtime. NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Projects
Go Compiler / Runtime
Status: All-But-Submitted
Milestone
Go1.23
Development

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4 participants
@ALTree @cuonglm @gopherbot @ipfreely-uk