Add slog compatibility, move to Go 1.21

errtrace.go

@@ -54,7 +54,7 @@ func wrap(err error, callerPC uintptr) error {
 }
 
 // Format writes the return trace for given error to the writer.
-// The output takes a fromat similar to the following:
+// The output takes a format similar to the following:
 //
 //	<error message>
 //

go.mod

@@ -1,3 +1,3 @@
 module braces.dev/errtrace
 
-go 1.20
+go 1.21

log_go121.go

@@ -0,0 +1,34 @@
+//go:build go1.21
+
+package errtrace
+
+import (
+	"bytes"
+	"log/slog"
+)
+
+// LogValue implements the [slog.LogValuer] interface.
+func (e *errTrace) LogValue() slog.Value {
+	var outb bytes.Buffer
+	err := writeTree(&outb, buildTraceTree(e))
+	if err != nil {
+		return slog.GroupValue(
+			slog.String("message", e.Error()),
+			slog.Any("formatErr", err),
+		)
+	}
+
+	return slog.StringValue(outb.String())
+}
+
+// LogAttr builds a slog attribute for an error.
+// It will log the error with an error trace
+// if the error has been wrapped with this package.
+// Otherwise, the error message will be logged as is.
+//
+// Usage:
+//
+//	slog.Default().Error("msg here", errtrace.LogAttr(err))
+func LogAttr(err error) slog.Attr {
+	return slog.Any("error", err)
+}