[xerrors] support joined errors in IsTimeout function

xerrors/errors.go

@@ -2,6 +2,7 @@ package xerrors
 
 import (
 	"errors"
+	"slices"
 )
 
 // IsTimeout reports whether the provided error indicates a timeout condition.
@@ -10,11 +11,14 @@ func IsTimeout(err error) bool {
 		return false
 	}
 
-	e, ok := err.(interface{ Timeout() bool })
-	if ok && e.Timeout() {
+	if te, ok := err.(interface{ Timeout() bool }); ok && te.Timeout() {
 		return true
 	}
 
+	if joined, ok := err.(interface{ Unwrap() []error }); ok {
+		return slices.ContainsFunc(joined.Unwrap(), IsTimeout)
+	}
+
 	inner := errors.Unwrap(err)
 
 	return inner != nil && IsTimeout(inner)

xerrors/errors_test.go

@@ -2,6 +2,7 @@ package xerrors_test
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"testing"
 
@@ -24,6 +25,8 @@ func TestIsTimeout(t *testing.T) {
 		{name: "context timeout", err: context.DeadlineExceeded, want: true},
 		{name: "wrapped context timeout", err: fmt.Errorf("bad stuff: %w", context.DeadlineExceeded), want: true},
 		{name: "custom timeout", err: customTimeoutError{}, want: true},
+		{name: "joined errors", err: errors.Join(errors.New("oops"), context.DeadlineExceeded), want: true},
+		{name: "joined errors - no timeout", err: errors.Join(errors.New("oops"), errors.New("ididitagain")), want: false},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {