log/slog: Group takes ...any

The Group function takes a key and a ...any, which is converted
into attrs.

Fixes #59204.

Change-Id: Ib714365dcda2eda37863ce433f3dd8cf5eeda610
Reviewed-on: https://go-review.googlesource.com/c/go/+/487855
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

api/next/56345.txt

@@ -47,7 +47,6 @@ pkg log/slog, func Error(string, ...interface{}) #56345
 pkg log/slog, func ErrorCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, func Float64(string, float64) Attr #56345
 pkg log/slog, func Float64Value(float64) Value #56345
-pkg log/slog, func Group(string, ...Attr) Attr #56345
 pkg log/slog, func GroupValue(...Attr) Value #56345
 pkg log/slog, func Info(string, ...interface{}) #56345
 pkg log/slog, func InfoCtx(context.Context, string, ...interface{}) #56345

api/next/59204.txt

@@ -0,0 +1 @@
+pkg log/slog, func Group(string, ...interface{}) Attr #59204

src/log/slog/attr.go

@@ -58,14 +58,26 @@ func Duration(key string, v time.Duration) Attr {
 }
 
 // Group returns an Attr for a Group Value.
-// The caller must not subsequently mutate the
-// argument slice.
+// The first argument is the key; the remaining arguments
+// are converted to Attrs as in [Logger.Log].
 //
-// Use Group to collect several Attrs under a single
+// Use Group to collect several key-value pairs under a single
 // key on a log line, or as the result of LogValue
 // in order to log a single value as multiple Attrs.
-func Group(key string, as ...Attr) Attr {
-	return Attr{key, GroupValue(as...)}
+func Group(key string, args ...any) Attr {
+	return Attr{key, GroupValue(argsToAttrSlice(args)...)}
+}
+
+func argsToAttrSlice(args []any) []Attr {
+	var (
+		attr  Attr
+		attrs []Attr
+	)
+	for len(args) > 0 {
+		attr, args = argsToAttr(args)
+		attrs = append(attrs, attr)
+	}
+	return attrs
 }
 
 // Any returns an Attr for the supplied value.

src/log/slog/doc.go

@@ -164,11 +164,11 @@ How this qualification is displayed depends on the handler.
 [TextHandler] separates the group and attribute names with a dot.
 [JSONHandler] treats each group as a separate JSON object, with the group name as the key.
 
-Use [Group] to create a Group Attr from a name and a list of Attrs:
+Use [Group] to create a Group Attr from a name and a list of key-value pairs:
 
 	slog.Group("request",
-	    slog.String("method", r.Method),
-	    slog.Any("url", r.URL))
+	    "method", r.Method,
+	    "url", r.URL)
 
 TextHandler would display this group as
 

src/log/slog/logger.go

@@ -95,16 +95,8 @@ func (l *Logger) Handler() Handler { return l.handler }
 // The new Logger's handler is the result of calling WithAttrs on the receiver's
 // handler.
 func (l *Logger) With(args ...any) *Logger {
-	var (
-		attr  Attr
-		attrs []Attr
-	)
-	for len(args) > 0 {
-		attr, args = argsToAttr(args)
-		attrs = append(attrs, attr)
-	}
 	c := l.clone()
-	c.handler = l.handler.WithAttrs(attrs)
+	c.handler = l.handler.WithAttrs(argsToAttrSlice(args))
 	return c
 }