fix: improve skip details (#4522)

log all skip reasons instead of only one, using a multierror.Error to
merge them all.

refs https://github.com/orgs/goreleaser/discussions/4469

---------

Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

internal/semerrgroup/sem.go

@@ -6,6 +6,7 @@ import (
 	"sync"
 
 	"github.com/goreleaser/goreleaser/internal/pipe"
+	"github.com/hashicorp/go-multierror"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -30,9 +31,9 @@ func NewSkipAware(g Group) Group {
 }
 
 type skipAwareGroup struct {
-	g        Group
-	skipErr  error
-	skipOnce sync.Once
+	g       Group
+	skipErr *multierror.Error
+	l       sync.Mutex
 }
 
 // Go execs runs `fn` and saves the result if no error has been encountered.
@@ -42,9 +43,9 @@ func (s *skipAwareGroup) Go(fn func() error) {
 		// if the err is a skip, set it for later, but return nil for now so the
 		// group proceeds.
 		if pipe.IsSkip(err) {
-			s.skipOnce.Do(func() {
-				s.skipErr = err
-			})
+			s.l.Lock()
+			defer s.l.Unlock()
+			s.skipErr = multierror.Append(s.skipErr, err)
 			return nil
 		}
 		return err
@@ -57,5 +58,13 @@ func (s *skipAwareGroup) Wait() error {
 	if err := s.g.Wait(); err != nil {
 		return err
 	}
+	if s.skipErr == nil {
+		return nil
+	}
+
+	if s.skipErr.Len() == 1 {
+		return s.skipErr.Errors[0]
+	}
+
 	return s.skipErr
 }

internal/semerrgroup/sem_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/goreleaser/goreleaser/internal/pipe"
+	"github.com/hashicorp/go-multierror"
 	"github.com/stretchr/testify/require"
 )
 
@@ -71,19 +72,49 @@ func TestSemaphoreSkipAware(t *testing.T) {
 	for _, i := range []int{1, 4} {
 		t.Run(fmt.Sprintf("limit-%d", i), func(t *testing.T) {
 			g := NewSkipAware(New(i))
-			var lock sync.Mutex
-			var counter int
 			for i := 0; i < 10; i++ {
 				g.Go(func() error {
 					time.Sleep(10 * time.Millisecond)
-					lock.Lock()
-					counter++
-					lock.Unlock()
 					return pipe.Skip("fake skip")
 				})
 			}
+			merr := &multierror.Error{}
+			require.ErrorAs(t, g.Wait(), &merr, "must be a multierror")
+			require.Len(t, merr.Errors, 10)
+		})
+	}
+}
+
+func TestSemaphoreSkipAwareSingleError(t *testing.T) {
+	for _, i := range []int{1, 4} {
+		t.Run(fmt.Sprintf("limit-%d", i), func(t *testing.T) {
+			g := NewSkipAware(New(i))
+			for i := 0; i < 10; i++ {
+				i := i
+				g.Go(func() error {
+					time.Sleep(10 * time.Millisecond)
+					if i == 5 {
+						return pipe.Skip("fake skip")
+					}
+					return nil
+				})
+			}
 			require.EqualError(t, g.Wait(), "fake skip")
-			require.Equal(t, 10, counter)
+		})
+	}
+}
+
+func TestSemaphoreSkipAwareNoSkips(t *testing.T) {
+	for _, i := range []int{1, 4} {
+		t.Run(fmt.Sprintf("limit-%d", i), func(t *testing.T) {
+			g := NewSkipAware(New(i))
+			for i := 0; i < 10; i++ {
+				g.Go(func() error {
+					time.Sleep(10 * time.Millisecond)
+					return nil
+				})
+			}
+			require.NoError(t, g.Wait())
 		})
 	}
 }