x/text/unicode/bidi: ReverseString doesn't preserve modifiers #50633
Description
What version of Go are you using (go version)?
$ go version go version go1.17.4 darwin/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="/Users/hajimehoshi/Library/Caches/go-build" GOENV="/Users/hajimehoshi/Library/Application Support/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="darwin" GOINSECURE="" GOMODCACHE="/Users/hajimehoshi/go/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="darwin" GOPATH="/Users/hajimehoshi/go" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/usr/local/go" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64" GOVCS="" GOVERSION="go1.17.4" GCCGO="gccgo" AR="ar" CC="clang" CXX="clang++" CGO_ENABLED="1" GOMOD="/Users/hajimehoshi/ebiten/go.mod" CGO_CFLAGS="-g -O2" CGO_CPPFLAGS="" CGO_CXXFLAGS="-g -O2" CGO_FFLAGS="-g -O2" CGO_LDFLAGS="-g -O2" PKG_CONFIG="pkg-config" GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/60/khbk2xqn1c5bml1byjn89dwc0000gn/T/go-build4087252806=/tmp/go-build -gno-record-gcc-switches -fno-common"
What did you do?
Run this with x/text 0.3.7
package main
import (
"fmt"
"golang.org/x/text/unicode/bidi"
)
func main() {
str := "a\u0308u"
fmt.Println(str)
fmt.Println(bidi.ReverseString(str))
}What did you expect to see?
äu
uä
The document of ReverseString says:
Modifiers will still follow the runes they modify.
So the modifiers should be reserved. Probably this is the same for AppendReverse.
By the way, in the ideal world, should all the graphemes be reserved (e.g., emoji flags)?
What did you see instead?
äu
üa
CC /@pgundlach