reflect:documentation for IsValid and IsZero is confusing

[mohit10verma]

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

$ go version
go version go1.13 linux/amd64

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="amd64"
GOBIN=""
GOCACHE="/home/administrator/.cache/go-build"
GOENV="/home/administrator/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/administrator/Work/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/administrator/Work/go/src/go-latest"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/administrator/Work/go/src/go-latest/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build484657166=/tmp/go-build -gno-record-gcc-switches"

What did you do?

https://play.golang.org/p/GYF3SFr7z77

What did you expect to see?

For a zero value,
value.IsZero() = true , and
value.IsValid() = false
according to the documentation here: https://golang.org/pkg/reflect/#Value.IsValid

What did you see instead?

value.IsZero() = true
value.IsValid() = true

[dsnet]

This is working as intended, but slightly confusing in the documentation.

The documentation for reflect.Value.IsValid says "It returns false if v is the zero Value". Note the uppercase Value, it's referring to the reflect.Value, an abstract representation of any Go value.

The documentation for reflect.Value.IsZero says "IsZero reports whether v is the zero value for its type". Note the lowercase value, it's referring the underlying Go value that the reflect.Value is representing.

[gopherbot]

Change https://golang.org/cl/193841 mentions this issue: reflect: enhance docs for IsZero and IsValid