oteslog: Improve transforming slog.KindAny attributes (#6254)

Reuse convertValue in otelslog.

Follows
#6237.

CHANGELOG.md

@@ -8,6 +8,11 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Added
+
+- Transform raw (`slog.KindAny`) attribute values to matching `log.Value` types.
+  For example, `[]string{"foo", "bar"}` attribute value is now transformed to `log.SliceValue(log.StringValue("foo"), log.StringValue("bar"))` instead of `log.String("[foo bar"])`. (#6254)
+
 ### Fixed
 
 - Transform nil attribute values to `log.Value` zero value instead of panicking in `go.opentelemetry.io/contrib/bridges/otellogrus`. (#6237)

bridges/otellogrus/hook.go

@@ -27,7 +27,7 @@
 //   - [logrus.PanicLevel] is transformed to [log.SeverityFatal4]
 //
 // Field values are transformed based on their type into log attributes, or
-// into a string value if there is no matching type.
+// into a string value encoded using [fmt.Sprintf] if there is no matching type.
 //
 // [OpenTelemetry]: https://opentelemetry.io/docs/concepts/signals/logs/
 package otellogrus // import "go.opentelemetry.io/contrib/bridges/otellogrus"

bridges/otelslog/convert.go

@@ -0,0 +1,123 @@
+// Code created by gotmpl. DO NOT MODIFY.
+// source: internal/shared/logutil/convert.go.tmpl
+
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package otelslog // import "go.opentelemetry.io/contrib/bridges/otelslog"
+
+import (
+	"fmt"
+	"math"
+	"reflect"
+	"strconv"
+	"time"
+
+	"go.opentelemetry.io/otel/log"
+)
+
+// convertValue converts various types to log.Value.
+func convertValue(v any) log.Value {
+	// Handling the most common types without reflect is a small perf win.
+	switch val := v.(type) {
+	case bool:
+		return log.BoolValue(val)
+	case string:
+		return log.StringValue(val)
+	case int:
+		return log.Int64Value(int64(val))
+	case int8:
+		return log.Int64Value(int64(val))
+	case int16:
+		return log.Int64Value(int64(val))
+	case int32:
+		return log.Int64Value(int64(val))
+	case int64:
+		return log.Int64Value(val)
+	case uint:
+		return convertUintValue(uint64(val))
+	case uint8:
+		return log.Int64Value(int64(val))
+	case uint16:
+		return log.Int64Value(int64(val))
+	case uint32:
+		return log.Int64Value(int64(val))
+	case uint64:
+		return convertUintValue(val)
+	case uintptr:
+		return convertUintValue(uint64(val))
+	case float32:
+		return log.Float64Value(float64(val))
+	case float64:
+		return log.Float64Value(val)
+	case time.Duration:
+		return log.Int64Value(val.Nanoseconds())
+	case complex64:
+		r := log.Float64("r", real(complex128(val)))
+		i := log.Float64("i", imag(complex128(val)))
+		return log.MapValue(r, i)
+	case complex128:
+		r := log.Float64("r", real(val))
+		i := log.Float64("i", imag(val))
+		return log.MapValue(r, i)
+	case time.Time:
+		return log.Int64Value(val.UnixNano())
+	case []byte:
+		return log.BytesValue(val)
+	case error:
+		return log.StringValue(val.Error())
+	}
+
+	t := reflect.TypeOf(v)
+	if t == nil {
+		return log.Value{}
+	}
+	val := reflect.ValueOf(v)
+	switch t.Kind() {
+	case reflect.Struct:
+		return log.StringValue(fmt.Sprintf("%+v", v))
+	case reflect.Slice, reflect.Array:
+		items := make([]log.Value, 0, val.Len())
+		for i := 0; i < val.Len(); i++ {
+			items = append(items, convertValue(val.Index(i).Interface()))
+		}
+		return log.SliceValue(items...)
+	case reflect.Map:
+		kvs := make([]log.KeyValue, 0, val.Len())
+		for _, k := range val.MapKeys() {
+			var key string
+			switch k.Kind() {
+			case reflect.String:
+				key = k.String()
+			default:
+				key = fmt.Sprintf("%+v", k.Interface())
+			}
+			kvs = append(kvs, log.KeyValue{
+				Key:   key,
+				Value: convertValue(val.MapIndex(k).Interface()),
+			})
+		}
+		return log.MapValue(kvs...)
+	case reflect.Ptr, reflect.Interface:
+		if val.IsNil() {
+			return log.Value{}
+		}
+		return convertValue(val.Elem().Interface())
+	}
+
+	// Try to handle this as gracefully as possible.
+	//
+	// Don't panic here. it is preferable to have user's open issue
+	// asking why their attributes have a "unhandled: " prefix than
+	// say that their code is panicking.
+	return log.StringValue(fmt.Sprintf("unhandled: (%s) %+v", t, v))
+}
+
+// convertUintValue converts a uint64 to a log.Value.
+// If the value is too large to fit in an int64, it is converted to a string.
+func convertUintValue(v uint64) log.Value {
+	if v > math.MaxInt64 {
+		return log.StringValue(strconv.FormatUint(v, 10))
+	}
+	return log.Int64Value(int64(v))
+}