cmd/vet: unexpected typecheck failures about "no field or method"

[fatedier]

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

$ go version
go1.11.4 and go1.12beta2

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/fate/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/fate/local/go_projects"
GOPROXY=""
GORACE=""
GOROOT="/Users/fate/.gvm/gos/go1.11.4"
GOTMPDIR=""
GOTOOLDIR="/Users/fate/.gvm/gos/go1.11.4/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/gx/5yxhg27n2n1c_blprt6c1_lm0000gn/T/go-build865449761=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

go vet report an error message but go build success.

Code on play.golang.org https://play.golang.org/p/fyn_dxhLQJC to reproduce the problem.

package main

import "fmt"

type A interface {
	Print()
	Print2()
}

type a struct {
}

func (a *a) Print() {
	fmt.Println("a")
}

func (a *a) Print2() {
	fmt.Println("a2")
}

type B struct {
	A
}

type C *B

func main() {
	b := &B{
		A: &a{},
	}
	test(b)
}

func test(c C) {
	c.Print()
	c.Print2()
}

What did you expect to see?

No typecheck failures.

What did you see instead?

When using go1.11.4:

# command-line-arguments
./a.go:35:4: invalid operation: c (variable of type C) has no field or method Print
./a.go:36:4: invalid operation: c (variable of type C) has no field or method Print2
vet: typecheck failures

When using go1.12beta2

# command-line-arguments
vet: ./a.go:35:4: c.Print undefined (type C has no field or method Print)