regexp compile an invalid regular expression: regexp.Compile("/dd[a-z]{,3}") returns no error

[panush]

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

$ go version
go version go1.16.2 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: GO111MODULE="" GOARCH="amd64" GOBIN="" GOCACHE="/$USER/.cache/go-build" GOENV="/$USER/.config/go/env" GOEXE="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/$USER/go/pkg/mod" GOOS="linux" GOPATH="/$USER/go" GOPROXY="https://proxy.golang.org,direct" GOSUMDB="sum.golang.org" GOTMPDIR="" GOVCS="" GOVERSION="go1.16.2" GCCGO="gccgo" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="/dev/null" CGO_CFLAGS="-g -O2" CGO_CPPFLAGS="" CGO_CXXFLAGS="-g -O2" CGO_FFLAGS="-g -O2" CGO_LDFLAGS="-lhs -L/usr/local/lib/" PKG_CONFIG="pkg-config" GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1019713328=/tmp/go-build -gno-record-gcc-switches"

$ go env

What did you do?

https://play.golang.org/p/4d7gR_xDEDB

reg, err2 := regexp.Compile("/dd[a-z]{,3}")

What did you expect to see?

I expect Compile to return some error since I'm using an invalid regular expression

What did you see instead?

Compile returned a nil error and a valid regexp object.

[seankhliao]

This is a valid regex https://play.golang.org/p/LRMBKINXzbH