cmd/compile: internal compiler error: name too long

[elagergren-spideroak]

Please answer these questions before submitting your issue. Thanks!

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

1.11, darwin/amd64

What did you do?

https://play.golang.org/p/WNDetHOIGt3

$ cat x.go
package tmp

type Q interface {
	Foo()
	Bar()
	Baz()
}

type B interface {
	B() Q
}

type O interface {
	O() interface {
		O
		B
		Q
	}
}

type W interface {
	W() interface {
		O
		B
		Q
	}
}

type S interface {
	S() interface {
		S
		W
		Q
	}
}

# _/tmp
<autogenerated>:1: internal compiler error: name too long: *interface { Bar(); Baz(); Foo(); S() interface { Bar(); Baz(); Foo(); S() interface { Bar(); Baz(); 
[ ... ]
Baz(); Foo(); O() interface { B() tmp.Q; Bar(); Baz(); Foo(); O() interface { B() tmp.Q; Bar(); Baz(); Foo(); O() interface { B<...>; Bar<...>; Baz<...>; Foo<...>; O<...> } } } } } } } } 
[ ... ]

Please file a bug report including a short program that triggers the error.
https://golang.org/issue/new

If you remove S, it compiles just fine.

Related, if only tangentially, to #26863.

[elagergren-spideroak]

Doesn't seem to be a regression from 1.10.3 or 1.9.7.

[josharian]

@griesemer @mdempsky

[griesemer]

A typical case of infinite interface expansion when creating the type name during object file generation. Not related to exports. Related to #26863 only insofar that in both cases an recursive algorithm stack-overflows (but the code is completely unrelated).

[griesemer]

@mdempsky Added you only in case you feel so inclined.

[griesemer]

Too late for 1.12.

[elagergren-spideroak]

FWIW, the original (proprietary) code that triggered this problem can't be reproduced on 1.11.5, but the code in the playground link can.

$ go1.11.5 test -failfast -v ./...
$ go test -failfast -v ./... # 1.12
# [redacted]
<autogenerated>:1: internal compiler error: name too long: