Given a go file with structs and interfaces that have an unexported field/method followed by an exported field/method:

package e

type A struct {
	hidden int

	Visible int
}

type B struct {
	hidden int

	// Visible is exported.
	Visible int
}

type C interface {
	hidden()

	Visible()
}

type D interface {
	hidden()

	// Visible is exported.
	Visible()
}

then running for type in A B C D; do go doc . $type; done, for go version go version go1.11.2 darwin/amd64, prints:

package e // import "."

type A struct {
	Visible int
	// Has unexported fields.
}
package e // import "."

type B struct {

	// Visible is exported.
	Visible int
	// Has unexported fields.
}
package e // import "."

type C interface {
	Visible()
	// Has unexported methods.
}
package e // import "."

type D interface {

	// Visible is exported.
	Visible()
	// Has unexported methods.
}

For tip version go version devel +950100a95c Fri Nov 30 19:11:39 2018 +0000 darwin/amd64, the above loop prints:

type A struct {
	Visible int
	// Has unexported fields.
}

type B struct {

	// Visible is exported.
	Visible int
	// Has unexported fields.
}

type C interface {
	Visible()
	// Has unexported methods.
}

type D interface {

	// Visible is exported.
	Visible()
	// Has unexported methods.
}

which is the same effective output, except it doesn't contain the package e // import "." lines. I skimmed through the issues involving doc for the Go 1.12 milestone and I didn't notice whether that was a deliberate change, so that may be a separate issue altogether.

For types B and D, which have a godoc comment associated with the exported field/method, there is a leading blank line inside the type. Types A and C do not have godoc for the exported field/method and go doc does not produce a leading blank line for them.

The leading blank line for B and D seems to be unnecessary visual stutter. It would be better if the output did not have any leading blank lines in the types, like so:

type A struct {
	Visible int
	// Has unexported fields.
}

type B struct {
	// Visible is exported.
	Visible int
	// Has unexported fields.
}

type C interface {
	Visible()
	// Has unexported methods.
}

type D interface {
	// Visible is exported.
	Visible()
	// Has unexported methods.
}

I first noticed the leading blank line on the godoc for runtime.MemStats: https://tip.golang.org/pkg/runtime/#MemStats. I'm not sure what other standard library types are printed this way, if any.