Update

vendor/golang.org/x/sync/errgroup/errgroup.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Package errgroup provides synchronization, error propagation, and Context
-// cancelation for groups of goroutines working on subtasks of a common task.
+// cancellation for groups of goroutines working on subtasks of a common task.
 //
 // [errgroup.Group] is related to [sync.WaitGroup] but adds handling of tasks
 // returning errors.
@@ -18,7 +18,7 @@ import (
 type token struct{}
 
 // A Group is a collection of goroutines working on subtasks that are part of
-// the same overall task.
+// the same overall task. A Group should not be reused for different tasks.
 //
 // A zero Group is valid, has no limit on the number of active goroutines,
 // and does not cancel on error.
@@ -46,7 +46,7 @@ func (g *Group) done() {
 // returns a non-nil error or the first time Wait returns, whichever occurs
 // first.
 func WithContext(ctx context.Context) (*Group, context.Context) {
-	ctx, cancel := withCancelCause(ctx)
+	ctx, cancel := context.WithCancelCause(ctx)
 	return &Group{cancel: cancel}, ctx
 }
 
@@ -61,11 +61,14 @@ func (g *Group) Wait() error {
 }
 
 // Go calls the given function in a new goroutine.
-// It blocks until the new goroutine can be added without the number of
-// active goroutines in the group exceeding the configured limit.
 //
-// The first call to return a non-nil error cancels the group's context, if the
-// group was created by calling WithContext. The error will be returned by Wait.
+// The first call to Go must happen before a Wait.
+// It blocks until the new goroutine can be added without the number of
+// goroutines in the group exceeding the configured limit.
+//
+// The first goroutine in the group that returns a non-nil error will
+// cancel the associated Context, if any. The error will be returned
+// by Wait.
 func (g *Group) Go(f func() error) {
 	if g.sem != nil {
 		g.sem <- token{}
@@ -75,6 +78,18 @@ func (g *Group) Go(f func() error) {
 	go func() {
 		defer g.done()
 
+		// It is tempting to propagate panics from f()
+		// up to the goroutine that calls Wait, but
+		// it creates more problems than it solves:
+		// - it delays panics arbitrarily,
+		//   making bugs harder to detect;
+		// - it turns f's panic stack into a mere value,
+		//   hiding it from crash-monitoring tools;
+		// - it risks deadlocks that hide the panic entirely,
+		//   if f's panic leaves the program in a state
+		//   that prevents the Wait call from being reached.
+		// See #53757, #74275, #74304, #74306.
+
 		if err := f(); err != nil {
 			g.errOnce.Do(func() {
 				g.err = err
@@ -129,8 +144,8 @@ func (g *Group) SetLimit(n int) {
 		g.sem = nil
 		return
 	}
-	if len(g.sem) != 0 {
-		panic(fmt.Errorf("errgroup: modify limit while %v goroutines in the group are still active", len(g.sem)))
+	if active := len(g.sem); active != 0 {
+		panic(fmt.Errorf("errgroup: modify limit while %v goroutines in the group are still active", active))
 	}
 	g.sem = make(chan token, n)
 }