spec: incorrect requirement for the embedded field

[leabit]

What is the URL of the page with the issue?

https://go.dev/ref/spec#Struct_types

What is your user agent?

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36

Screenshot

No response

What did you do?

I came across a discussion about the incorrect terminology used in the specification when referring to promoted methods of the alias to unnamed type, and the changes that were made to address this issue. However, there remains another related problem, and I believe its resolution should also be considered as part of the overall solution. The specification states the following:

An embedded field must be specified as a type name T or as a pointer to a non-interface type name *T, and T itself may not be a pointer type.

If the type name denotes only defined types everything would be fine, however, it also denotes type alias to the unnamed (undefined) types.

What did you see happen?

So according to the specification, the following code is invalid since type name T is a pointer type:

package main

type T = *int

type S struct {
	T
}

func main() {}

However, it compiles.

What did you expect to see?

To not compile (actually to compile, but to correct the specification to properly address this as well).

[gabyhelp]

Related Issues and Documentation

• spec: Embedded fields don't need to be defined types #41687 (closed)
• cmd/go2go: embedded generic pointer field cannot be referred to by name #40059 (closed)
• spec: some wording need to be adjusted for embedding alias of pointer types #22005
• go/types: position of field Var S.T in type S struct{ p.T } coincides with p, not T #60372 (closed)
• spec: EBNF for struct types does not permit embedding instantiated types #53240 (closed)
• cmd/compile: imperfect error message for embedding alias of pointer types #22004 (closed)
• cmd/compile: failure to reject embedding of unsafe.Pointer in struct #14729 (closed)
• gccgo: aliases of *T should be embeddable if T is a defined type which is neither pointer nor interface #36153
• go/types, types2: embedded field type cannot be a (pointer to a) type parameter #48334 (closed)
• cmd/go2go: misleading error for embedded struct field of type parameter #39774 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[leabit]

Al right, it looks like the same issue was already mentioned in #22005, however, nothing has been done for 7 years

[seankhliao]

Duplicate of #22005