netip.ParsePrefix must not silently accept ip4in6 address

[gaissmai]

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

$ go version
go version go1.18.2 linux/amd64

Does this issue reproduce with the latest release?

it is the latest stable version

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/gaissmai/.cache/go-build"
GOENV="/home/gaissmai/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/gaissmai/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/gaissmai/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/snap/go/9760"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/snap/go/9760/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18.2"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1324338144=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.18.2 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.18.2
uname -sr: Linux 5.13.0-44-generic
Distributor ID:	Ubuntu
Description:	Ubuntu 21.10
Release:	21.10
Codename:	impish
gdb --version: GNU gdb (Ubuntu 11.1-0ubuntu2) 11.1

What did you do?

https://go.dev/play/p/apYQXnnLnTv

What did you expect to see?

panic, netip.MustParsePrefix() should panic on a 4in6 IP address
or at least not silently try this address as IP6

What did you see instead?

inet.MustParsePrefix() did not panic and silently makes an IPv6 address from the 4in6 address

[gaissmai]

sorry,there is a typo in my IP address, must more investigate, forget it