runtime: function-scoped generic types with the same name and parameters are treated as the same in interface, causing segfault

[ohijiho]

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

$ go version
go version go1.19.12 darwin/arm64

Does this issue reproduce with the latest release?

No, only reproducible with version before 1.20.

I checked that it's reproducible with docker images golang:1.18.10-alpine, 1.19.0-alpine, and 1.19.12-alpine.

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

go env Output

$ go env
GO111MODULE="on"
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/jiho.park/Library/Caches/go-build"
GOENV="/Users/jiho.park/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/jiho.park/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/jiho.park/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/jiho.park/sdk/go1.19.12"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/jiho.park/sdk/go1.19.12/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.19.12"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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/m2/xcs64bj145x1v3vcr4kzbb_whbnl4r/T/go-build4205325580=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

func main() {
	fmt.Println(reflect.TypeOf(i1()).Kind())
	fmt.Println(reflect.TypeOf(i2()).Kind())
	fmt.Println(reflect.TypeOf(i3()).Kind())
	fmt.Println(reflect.TypeOf(i1()) == reflect.TypeOf(i3()))
}

func i1() any {
	type t[T any] string
	return t[int]("")
}

func i2() any {
	type t[T any] int
	return t[int](0)
}

func i3() any {
	type t[T any] struct{}
	return t[int]{}
}

The function-scoped types should be a generic type with the same name, and initiated with the same type parameters.

What did you expect to see?

string
int
struct
false
 0 {}

What did you see instead?

struct
struct
struct
true
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x0 pc=0x104358798]

goroutine 1 [running]:
fmt.(*buffer).writeString(...)
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:82
fmt.(*fmt).padString(0x104386fda?, {0x0, 0xa})
        /Users/jiho.park/sdk/go1.19.12/src/fmt/format.go:110 +0x224
fmt.(*fmt).fmtS(0x10b7f5701?, {0x0?, 0x14000098cd8?})
        /Users/jiho.park/sdk/go1.19.12/src/fmt/format.go:359 +0x40
fmt.(*pp).fmtString(0x10b7f5800?, {0x0?, 0x10bb2bfc8?}, 0x430f2ec?)
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:474 +0x98
fmt.(*pp).printValue(0x1400009e410, {0x1043af6a0?, 0x1043a7180?, 0xd0?}, 0x76, 0x0)
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:788 +0xf70
fmt.(*pp).printArg(0x1400009e410, {0x1043af6a0?, 0x1043a7180}, 0x76)
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:743 +0x788
fmt.(*pp).doPrintln(0x1400009e410, {0x14000098f38?, 0x3, 0x104386700?})
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:1200 +0x178
fmt.Fprintln({0x1043c0d58, 0x140000a0008}, {0x14000098f38, 0x3, 0x3})
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:284 +0x44
fmt.Println(...)
        /Users/jiho.park/sdk/go1.19.12/src/fmt/print.go:294
main.main()
        /Users/jiho.park/repos/test/asdf/main.go:29 +0x29c

[seankhliao]

we no longer support 1.19, it works on 1.21
https://go.dev/play/p/MVxRjc6G_oL