Could this also be the case (when using cgo):
phySize := unsafe.Sizeof(C.struct_ad9361_rf_phy)
giving a compile time error:
invalid expression unsafe.Sizeof(_Ctype_struct_ad9361_rf_phy)

@davmaz No, the problem there is simply that unsafe.Sizeof takes a value, not a type. It's not the same as the C sizeof operation.

In general, for the Go project, please ask questions in a forum rather than on the issue tracker. See https://golang.org/wiki/Questions. Thanks.

The problem is that when typechecking a pointer to a named type like *msg, cmd/compile recurses and tries to completely typecheck msg. Instead, we should just do the minimum to get a *Type value for msg (in this case a TFORW type) so we can construct the *msg pointer type. Later when we visit msg's type declaration, we can finish typechecking it.

A workaround is to move the hdr type declaration after the msg type declaration.

Quite possibly Robert's front end revamp will take care of this. Maybe not worth worrying about before then.

FWIW, gotype accepts this code w/o problems. Since there's a work-around per @mdempsky I don't think there's any urgency here.

Reproduced at tip (00263a8) on May 10, 2017.

Still seems low priority; punting to 1.10.

FWIW, gotype accepts this code w/o problems. Since there's a work-around per @mdempsky I don't think there's any urgency here.

FYI, both go/types and cmd/compile now reports an error as of go1.21 and tip:

$ go tool compile p.go
p.go:5:6: invalid recursive type hdr
	p.go:5:6: hdr refers to
	p.go:9:6: msg refers to
	p.go:14:7: hdrsize refers to
	p.go:5:6: hdr
$ gotype p.go
p.go:5:6: invalid recursive type hdr
p.go:5:6: 	hdr refers to
p.go:9:6: 	msg refers to
p.go:14:7: 	hdrsize refers to
p.go:5:6: 	hdr

Related #13890.