bytedance/sonic
Unmarshal to float32 yields different output than encoding/json
Aberta
#884 aberto em 3 de dez. de 2025
bughelp wanted
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Description
Describe the bug
Unmarshaling some values to float32 yields different output than encoding/json.
To Reproduce
Run the following code:
import (
"encoding/json"
"testing"
"github.com/bytedance/sonic"
"github.com/stretchr/testify/assert"
)
func TestPrecision(t *testing.T) {
b := []byte("7.328900098800659")
var js float32
var ss float32
_ = json.Unmarshal(b, &js)
_ = sonic.Unmarshal(b, &ss)
assert.Equal(t, js, ss) // js == 7.3289, ss == 7.3289003
}
Expected behavior
For sonic to return output exactly the same as encoding/json. I am guessing it is because sonic seems to unmarshal to float64 before casting the value to float32, which somehow seems to give less precision than parsing the value directly to float32.
Sonic version:
v1.14.2-0.20251010110621-72bd4caf6fb6
Environment:
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/bimoadityar/.cache/go-build"
GOENV="/home/bimoadityar/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/bimoadityar/.go/pkg/mod"
GOOS="linux"
GOPATH="/home/bimoadityar/.go"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/bimoadityar/.config/spkit/bin/sdk/go1.23.12"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/bimoadityar/.config/spkit/bin/sdk/go1.23.12/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.23.12"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/bimoadityar/Documents/bimo-test-2/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 -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1204808054=/tmp/go-build -gno-record-gcc-switches"