The gc compiler issues a spurious error for this comparison:

(*int)(nil) == interface{}(nil) // gc: illegal constant expression: *int == interface {}

For some reason it seems to consider the operands to the comparison to be constants, even though they are both nil (and thus not even values of a type that has constants).

When the operands are bound to variables, the error goes away:

func _(p *int, q interface{}) bool { return p == q }

go/types correctly reports no error.

See https://play.golang.org/p/gtgb4En-KE

$ go version
go version devel +31ad583 Wed Aug 10 19:44:08 2016 +0000 darwin/amd64