resolver: preserve OS version in worker platforms

build/resolver/driver.go

@@ -10,6 +10,7 @@ import (
 	"github.com/containerd/platforms"
 	"github.com/docker/buildx/builder"
 	"github.com/docker/buildx/driver"
+	"github.com/docker/buildx/util/platformutil"
 	"github.com/docker/buildx/util/progress"
 	"github.com/moby/buildkit/client"
 	gateway "github.com/moby/buildkit/frontend/gateway/client"
@@ -147,17 +148,11 @@ func (r *nodeResolver) Resolve(ctx context.Context, optPlatforms map[string][]oc
 				if err != nil {
 					return errors.Wrap(err, "listing workers")
 				}
-
-				ps := make(map[string]ocispecs.Platform, len(ww))
+				var ps []ocispecs.Platform
 				for _, w := range ww {
-					for _, p := range w.Platforms {
-						pk := platforms.Format(platforms.Normalize(p))
-						ps[pk] = p
-					}
-				}
-				for _, p := range ps {
-					workers[i] = append(workers[i], p)
+					ps = append(ps, w.Platforms...)
 				}
+				workers[i] = platformutil.Dedupe(ps)
 				return nil
 			})
 		}

util/platformutil/parse.go

@@ -43,7 +43,7 @@ func Dedupe(in []ocispecs.Platform) []ocispecs.Platform {
 	out := make([]ocispecs.Platform, 0, len(in))
 	for _, p := range in {
 		p := platforms.Normalize(p)
-		key := platforms.Format(p)
+		key := platforms.FormatAll(p)
 		if _, ok := m[key]; ok {
 			continue
 		}

util/platformutil/parse_test.go

@@ -0,0 +1,37 @@
+package platformutil
+
+import (
+	"testing"
+
+	"github.com/containerd/platforms"
+	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDedupePreservesOSVersionAndFeatures(t *testing.T) {
+	t.Parallel()
+
+	got := Dedupe([]ocispecs.Platform{
+		platforms.MustParse("windows(10.0.17763)/amd64"),
+		platforms.MustParse("windows(10.0.20348)/amd64"),
+		platforms.MustParse("windows(10.0.20348+win32k)/amd64"),
+		platforms.MustParse("windows(10.0.17763)/amd64"),
+		platforms.MustParse("linux/x86_64"),
+		platforms.MustParse("linux/amd64"),
+	})
+
+	require.Equal(t, []string{
+		"windows(10.0.17763)/amd64",
+		"windows(10.0.20348)/amd64",
+		"windows(10.0.20348+win32k)/amd64",
+		"linux/amd64",
+	}, formatAll(got))
+}
+
+func formatAll(pp []ocispecs.Platform) []string {
+	out := make([]string, 0, len(pp))
+	for _, p := range pp {
+		out = append(out, platforms.FormatAll(p))
+	}
+	return out
+}