Fix exclude_type on non imported package (#3717)

Author: emcfarlane

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## [Unreleased]
 
-- No changes yet.
+- Fix `exclude_type` on a non imported package.
 
 ## [v1.51.0] - 2025-03-28
 

private/bufpkg/bufimage/bufimageutil/bufimageutil_test.go

@@ -101,6 +101,10 @@ func TestTypes(t *testing.T) {
 		t.Parallel()
 		runDiffTest(t, "testdata/options", "pkg.FooService.Do.exclude.txtar", WithExcludeTypes("pkg.FooService.Do"))
 	})
+	t.Run("exclude-package", func(t *testing.T) {
+		t.Parallel()
+		runDiffTest(t, "testdata/options", "pkg.Pkg.exclude.txtar", WithExcludeTypes("pkg"))
+	})
 	t.Run("exclude-all", func(t *testing.T) {
 		t.Parallel()
 		runDiffTest(t, "testdata/options", "all.exclude.txtar", WithExcludeTypes("pkg.Foo", "pkg.FooEnum", "pkg.FooService"))

private/bufpkg/bufimage/bufimageutil/image_filter.go

@@ -56,7 +56,13 @@ func filterImage(image bufimage.Image, options *imageFilterOptions) (bufimage.Im
 			if file.IsImport() {
 				continue
 			}
-			if err := closure.addElement(file.FileDescriptorProto(), "", false, imageIndex, options); err != nil {
+			// Check if target package is filtered, this is not an error.
+			// These includes are implicitly added to the closure.
+			fileDescriptorProto := file.FileDescriptorProto()
+			if mode := closure.elements[fileDescriptorProto]; mode == inclusionModeExcluded {
+				continue
+			}
+			if err := closure.addElement(fileDescriptorProto, "", false, imageIndex, options); err != nil {
 				return nil, err
 			}
 		}