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go: float constants if set as expression (ex: 1/2) are calculated as ints #67544

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to6ka opened this issue May 21, 2024 · 1 comment
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go: float constants if set as expression (ex: 1/2) are calculated as ints #67544

to6ka opened this issue May 21, 2024 · 1 comment

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@to6ka
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to6ka commented May 21, 2024

Go version

go version go1.22.3 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/root/.cache/go-build'
GOENV='/root/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.22.3'
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-build1890607898=/tmp/go-build -gno-record-gcc-switches'

What did you do?

go run main.go
https://go.dev/play/p/96yzk2hhXjy

func main() {
	const f float64 = 1 / 2
	fmt.Println(f)
}

What did you see happen?

0

What did you expect to see?

0.5

or requirement to set types explicitly, because you cant do the same with variable without casting to type
@randall77
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This is how the language is currently specified: https://go.dev/ref/spec#Constant_expressions, the Θ example.

@gabyhelp gabyhelp mentioned this issue Nov 27, 2024
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@randall77 @to6ka