cmd/compile: panic when importing package contains self-referential generic interface type

[cuonglm]

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

$ go version
go version devel go1.18-b86e8dd0f3 Thu Sep 9 09:06:46 2021 +0000 darwin/arm64

Does this issue reproduce with the latest release?

No

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

go env Output

$ go env

What did you do?

Coming here from #48280, a variant of the program trigger another error:

-- p.go --
package p

type I[T I[T]] interface {
	F() T
}
-- p_test.go --
package p_test

import (
	"testing"

	"p"
)

type S struct{}

func (*S) F() *S { return nil }

func TestP(t *testing.T) {
	var _ p.I[*S] = &S{}
}

What did you expect to see?

Running go test passes.

What did you see instead?

/p_test.go:11:27: internal compiler error: importsym of symbol that already exists: p.I

goroutine 1 [running]:
runtime/debug.Stack()
	/Users/cuonglm/sources/go/src/runtime/debug/stack.go:24 +0x68
cmd/compile/internal/base.FatalfAt({0x1, 0x0}, {0x1031cd645, 0x2b}, {0x1400045cbb8, 0x1, 0x1})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/base/print.go:227 +0x16c
cmd/compile/internal/base.Fatalf(...)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/base/print.go:196
cmd/compile/internal/typecheck.importsym({0x1, 0x0}, 0x0, 0xa0, 0x1)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/typecheck/export.go:52 +0x84
cmd/compile/internal/typecheck.importtype({0x8f200, 0x140}, 0x102af89c0)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/typecheck/export.go:65 +0x28
cmd/compile/internal/typecheck.(*importReader).doDecl(0x1400008f200, 0x14000483e00)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/typecheck/iimport.go:326 +0x344
cmd/compile/internal/typecheck.expandDecl({0x1033efd70, 0x14000537540})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/typecheck/iimport.go:61 +0x19c
cmd/compile/internal/typecheck.Resolve({0x1033efd70, 0x14000537540})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/typecheck/typecheck.go:151 +0xe4
cmd/compile/internal/noder.(*irgen).obj(0x14000496000, {0x1033ec1b8, 0x14000489e00})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/object.go:61 +0x170
cmd/compile/internal/noder.(*irgen).typ0(0x14000496000, {0x1033db7d0, 0x14000480bd0})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/types.go:116 +0x2d0
cmd/compile/internal/noder.(*irgen).typ1(0x14000496000, {0x1033db7d0, 0x14000480bd0})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/types.go:60 +0x60
cmd/compile/internal/noder.(*irgen).typ(0x14000496000, {0x1033db7d0, 0x14000480bd0})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/types.go:35 +0x40
cmd/compile/internal/noder.(*irgen).obj(0x14000496000, {0x1033ec258, 0x14000490420})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/object.go:132 +0x84c
cmd/compile/internal/noder.(*irgen).def(0x14000496000, 0x14000411d20)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/object.go:22 +0xb4
cmd/compile/internal/noder.(*irgen).varDecl(0x14000496000, 0x14000537528, 0x1400012fc80)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/decl.go:222 +0xbc
cmd/compile/internal/noder.(*irgen).decls(0x803b78101, 0x0, {0x1400010cb50, 0x1, 0x0})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/decl.go:34 +0x11c
cmd/compile/internal/noder.(*irgen).stmt(0x14000496000, {0x1033dc250, 0x14000409050})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/stmt.go:54 +0x118
cmd/compile/internal/noder.(*irgen).stmts(0x1400006fb20, {0x1400010cb60, 0x1, 0x1400012cc58})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/stmt.go:19 +0x9c
cmd/compile/internal/noder.(*irgen).funcBody(0x14000496000, 0x1400043e9a0, 0x1400045d6d8, 0x14000131900, 0x14000131980)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/func.go:45 +0x224
cmd/compile/internal/noder.(*irgen).funcDecl.func1()
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/decl.go:128 +0x60
cmd/compile/internal/noder.(*irgen).generate(0x14000496000, {0x1400012c428, 0x1, 0xc0})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/irgen.go:263 +0x1cc
cmd/compile/internal/noder.check2({0x1400012c428, 0x1, 0x1})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/irgen.go:93 +0x130
cmd/compile/internal/noder.LoadPackage({0x140001360f0, 0x1, 0x0})
	/Users/cuonglm/sources/go/src/cmd/compile/internal/noder/noder.go:90 +0x2f0
cmd/compile/internal/gc.Main(0x1033cafb0)
	/Users/cuonglm/sources/go/src/cmd/compile/internal/gc/main.go:190 +0xbbc
main.main()
	/Users/cuonglm/sources/go/src/cmd/compile/main.go:55 +0xf8

FAIL	p [build failed]
FAIL

[gopherbot]

Change https://golang.org/cl/349011 mentions this issue: cmd/compile: prevent duplicated import symbol of generic type