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cmd/compile: miscompilation of anonymous, recursive interfaces #56057

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mdempsky opened this issue Oct 5, 2022 · 1 comment
Closed

cmd/compile: miscompilation of anonymous, recursive interfaces #56057

mdempsky opened this issue Oct 5, 2022 · 1 comment
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compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done.
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@mdempsky
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mdempsky commented Oct 5, 2022

The program below should run silently, but when compiled with cmd/compile it prints FAIL and different type signatures. It works correctly with gccgo.

$ cat z.go
package main

import "fmt"
import "reflect"

type I interface{ m() interface{ I } }

type J interface{ m() interface{ K } }
type K interface{ m() interface{ J } }

var i = reflect.TypeOf(new(interface{ I })).Elem()
var j = reflect.TypeOf(new(interface{ J })).Elem()
var k = reflect.TypeOf(new(interface{ K })).Elem()

func main() {
	if i != j || i != k || j != k {
		fmt.Println("FAIL")
		fmt.Println(i)
		fmt.Println(j)
		fmt.Println(k)
	}
}

$ go run z.go
FAIL
interface { main.m() interface { main.m@18 } }
interface { main.m() interface { main.m() interface { main.m@18 } } }
interface { main.m() interface { main.m() interface { main.m@18 } } }

The issue is that we're generating distinct link names for interface{ I } and interface{ J }, even though they denote identical types.

/cc @golang/compiler

@mdempsky mdempsky added the NeedsFix The path to resolution is known, but the work has not been done. label Oct 5, 2022
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Oct 5, 2022
@mknyszek mknyszek added this to the Go1.20 milestone Oct 12, 2022
@mdempsky mdempsky modified the milestones: Go1.20, Unplanned, Backlog Jan 10, 2023
@mdempsky
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mdempsky commented Sep 6, 2023

Since Go 1.20, cmd/compile rejects this code with "invalid recursive type: anonymous interface refers to itself".

@mdempsky mdempsky closed this as completed Sep 6, 2023
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Labels
compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done.
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