Compiled regex MatchString(string) with $ in compile expression and Hindi characters in match string.

[mdonahue-godaddy]

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

$ go version
1.20.x - 1.21.x

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='on'
GOARCH='arm64'
GOBIN=''
GOCACHE='[REDACTED]/Library/Caches/go-build'
GOENV='[REDACTED]/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='[REDACTED]/go/pkg/mod'
GONOPROXY='[REDACTED]'
GONOSUMDB='[REDACTED]'
GOOS='darwin'
GOPATH='[REDACTED]/go'
GOPRIVATE='[REDACTED]'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/homebrew/opt/go/libexec'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/opt/homebrew/opt/go/libexec/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.21.0'
GCCGO='gccgo'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='0'
GOMOD='[REDACTED]/github.com/[REDACTED]/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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/d9/fy99_6gj5dbb4fv8ns59wfx00000gq/T/go-build3450324136=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

Behavior present on latest macOS and in Go Playground https://play.golang.com/p/x6q9rbx33ag

package main

import (
	"fmt"
	"regexp"
)

const (
	DomainRegexText = `^[\p{L}\p{N}\-]{1,63}$`
)

func main() {
	domainRegex := regexp.MustCompile(DomainRegexText)
	domains := []string{"", "a", "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz-0123456789", "abcdefghijklmnopqrstuvwxyz-abcdefghijklmnopqrstuvwxyz-0123456789", "कारबीमा"}
	for _, domain := range domains {
		fmt.Printf("'%s' with len := %d\n", domain, len(domain))

		if domainRegex.MatchString(domain) {
			fmt.Println("REGEX matched!")
		} else {
			fmt.Println("REGEX did NOT match!!")
		}
	}
}

'' with len := 0
REGEX did NOT match!!
'a' with len := 1
REGEX matched!
'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz-0123456789' with len := 63
REGEX matched!
'abcdefghijklmnopqrstuvwxyz-abcdefghijklmnopqrstuvwxyz-0123456789' with len := 64
REGEX did NOT match!!
'कारबीमा' with len := 21
REGEX did NOT match!!

What did you expect to see?

I'm not a Hindi language expert, but it seems that 'कारबीमा' should match the RegEx

What did you see instead?

'कारबीमा' failed match

Dropping the $ from the compiled RegEx allows it to match, but then the size check fails over 63 characters (as it should).

[fzipp]

Not every rune in the string "कारबीमा" is a letter, some are marks:
https://go.dev/play/p/sF5sYpZRAeW

You can match marks with \p{M}.

[mdonahue-godaddy]

Thank you, will look at that closer.

[mdonahue-godaddy]

That resolved the issue. So the issue was on my side. Thanks again!