Allow int, uint, and floats as map keys (#958)

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

unmarshaler.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"math"
 	"reflect"
+	"strconv"
 	"strings"
 	"sync/atomic"
 	"time"
@@ -1079,6 +1080,33 @@ func (d *decoder) keyFromData(keyType reflect.Type, data []byte) (reflect.Value,
 			return reflect.Value{}, fmt.Errorf("toml: error unmarshalling key type %s from text: %w", stringType, err)
 		}
 		return mk.Elem(), nil
+
+	case keyType.Kind() == reflect.Int || keyType.Kind() == reflect.Int8 || keyType.Kind() == reflect.Int16 || keyType.Kind() == reflect.Int32 || keyType.Kind() == reflect.Int64:
+		key, err := strconv.ParseInt(string(data), 10, 64)
+		if err != nil {
+			return reflect.Value{}, fmt.Errorf("toml: error parsing key of type %s from integer: %w", stringType, err)
+		}
+		return reflect.ValueOf(key).Convert(keyType), nil
+	case keyType.Kind() == reflect.Uint || keyType.Kind() == reflect.Uint8 || keyType.Kind() == reflect.Uint16 || keyType.Kind() == reflect.Uint32 || keyType.Kind() == reflect.Uint64:
+		key, err := strconv.ParseUint(string(data), 10, 64)
+		if err != nil {
+			return reflect.Value{}, fmt.Errorf("toml: error parsing key of type %s from unsigned integer: %w", stringType, err)
+		}
+		return reflect.ValueOf(key).Convert(keyType), nil
+
+	case keyType.Kind() == reflect.Float32:
+		key, err := strconv.ParseFloat(string(data), 32)
+		if err != nil {
+			return reflect.Value{}, fmt.Errorf("toml: error parsing key of type %s from float: %w", stringType, err)
+		}
+		return reflect.ValueOf(float32(key)), nil
+
+	case keyType.Kind() == reflect.Float64:
+		key, err := strconv.ParseFloat(string(data), 64)
+		if err != nil {
+			return reflect.Value{}, fmt.Errorf("toml: error parsing key of type %s from float: %w", stringType, err)
+		}
+		return reflect.ValueOf(float64(key)), nil
 	}
 	return reflect.Value{}, fmt.Errorf("toml: cannot convert map key of type %s to expected type %s", stringType, keyType)
 }