encoding/xml: does not reject duplicate attribute names

[DemiMarie]

Go version

go version go1.21.11 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/user/.cache/go-build'
GOENV='/home/user/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/user/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/user/go'
GOPRIVATE=''
GOPROXY='direct'
GOROOT='/usr/lib/golang'
GOSUMDB='off'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/usr/lib/golang/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.11'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
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 -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3671854511=/tmp/go-build -gno-record-gcc-switches'

What did you do?

https://go.dev/play/p/TzV6Av9hMci

What did you see happen?

encoding/xml accepted <a a="" a=""/>, even though it has duplicate a attributes and so is ill-formed.

What did you expect to see?

encoding/xml should reject <a a="" a=""/> because it has duplicate a attributes and so is ill-formed.

[gabyhelp]

Related Issues

• encoding/xml: accepts various ill-formed XML #68293
• affected/package: xml/encoding #57802 (closed)
• encoding/xml: createAttrPrefix should ban "XMLanything" case insensitive, not just "xmlanything" #35151 (closed)
• encoding/xml: Encoder duplicates namespace tags #7535
• encoding/xml: accepts invalid XML with multiple colons #20396 (closed)
• encoding/xml: allows a colon before or after an XML name #68294
• encoding/xml: Decoder does not reject xml-ProcInst preceeded by other data #65691
• encoding/xml: encoding a start token with a namespace set in Name and Attr results in invalid XML #42807
• encoding/xml: disallow attributes named xmlns:* #8167
• encoding/xml: failure to handle conflicting tags in different namespaces #8535 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[cagedmantis]

@rsc

[cagedmantis]

Please note this related comment https://github.com/golang/go/issues/68293#issuecomment-2207866996

[DemiMarie]

Please note this related comment #68293 (comment)

68299 is that proposal