struct type conversion doesn't recursively evaluate type equivalence

[petemoore]

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

$ go version
1.20.2

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
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/pmoore/Library/Caches/go-build"
GOENV="/Users/pmoore/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/pmoore/.gvm/pkgsets/go1.20.2/global/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/pmoore/.gvm/pkgsets/go1.20.2/global"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/pmoore/.gvm/gos/go1.20.2"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/pmoore/.gvm/gos/go1.20.2/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.20.2"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/pmoore/git/d2g/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/kc/p5r32hgd42xcwxhc9lyfxtwm0000gn/T/go-build282360353=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

package structconvert

type (
	A1 struct {
		Member B1
	}
	A2 struct {
		Member B2
	}
	B1 struct {
		Switch bool
	}
	B2 struct {
		Switch bool
	}
)

func Convert() {
	_ = B2(B1{}) // ok
	_ = A2(A1{}) // not ok
}

What did you expect to see?

I expected the code to compile. I raised as a bug, but perhaps it is intentional that struct type conversion doesn't recursively evaluate struct equivalence? I'm not sure why it shouldn't though.

Related: #19778

What did you see instead?

Compilation error: cannot convert A1{} (value of type A1) to type A2

[seankhliao]

Duplicate of #18030