vendor: github.com/moby/buildkit v0.21.0-rc1

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

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

@@ -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
 }
 
@@ -61,6 +61,7 @@ func (g *Group) Wait() error {
 }
 
 // Go calls the given function in a new goroutine.
+// The first call to Go must happen before a Wait.
 // It blocks until the new goroutine can be added without the number of
 // active goroutines in the group exceeding the configured limit.
 //
@@ -118,6 +119,7 @@ func (g *Group) TryGo(f func() error) bool {
 
 // SetLimit limits the number of active goroutines in this group to at most n.
 // A negative value indicates no limit.
+// A limit of zero will prevent any new goroutines from being added.
 //
 // Any subsequent call to the Go method will block until it can add an active
 // goroutine without exceeding the configured limit.