fmt: fmt.Sscanln doesn't error when given an incorrect bool to scan

[ncw]

Go version

go version go1.21.4 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/ncw/.cache/go-build'
GOENV='/home/ncw/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/ncw/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/ncw/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/go/go1.21'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/opt/go/go1.21/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.4'
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-build4276667016=/tmp/go-build -gno-record-gcc-switches'

What did you do?

See: https://go.dev/play/p/UkzjB5-g2Fo

I ran

func main() {
	var o bool
	var in = "7"
	n, err := fmt.Sscanln(in, &o)
	fmt.Println(n, err)
	fmt.Println(o)
}

What did you see happen?

It produced

1 <nil>
false

Indicating that 1 argument had been successfully parsed as false.

What did you expect to see?

I expected to see this as I don't think "7" is a valid bool.

0 strconv.ParseBool: parsing "7": invalid syntax
false

Or possibly (but inconsistent with strconv.ParseBool)

1 <nil>
true

[gabyhelp]

Related Issues

• fmt: Sscanf accepts invalid boolean values #43306
• fmt: mishandling of FALSE in Scanf #2922 (closed)
• fmt: Scanf rejects \r\n at end of line on Windows #51346 (closed)
• fmt: Sscanf handles spaces and \n inconsistently #8515 (closed)
• Boolean literal are allowed to be used as variable names #36627 (closed)

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[ncw]

Good bot :-) I think this is a dupe of #43306 which I managed to miss in my searching so I'll close this.