chore: enable forcetypeassert linter, fix issues (#38804)

Enable [`forcetypeassert`](https://github.com/gostaticanalysis/forcetypeassert)
linter to prevent unchecked type assertions. ~650 issues fixed, most
fixes were clean, some use `setting.PanicInDevOrTesting`.

The only behaviour changes are where code would previously send a 500 error
or panic, a 4xx error is now emitted.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/packages/cargo/cargo.go

@@ -127,7 +127,7 @@ func SearchPackages(ctx *context.Context) {
 		crates = append(crates, &SearchResultCrate{
 			Name:          pd.Package.Name,
 			LatestVersion: pd.Version.Version,
-			Description:   pd.Metadata.(*cargo_module.Metadata).Description,
+			Description:   packages_model.DescriptorMetadata[*cargo_module.Metadata](pd).Description,
 		})
 	}
 

routers/api/packages/chef/auth.go

@@ -78,7 +78,12 @@ func (a *Auth) Verify(req *http.Request, w http.ResponseWriter, store auth.DataS
 		return nil, err
 	}
 
-	if err := verifySignedHeaders(req, version, pub.(*rsa.PublicKey)); err != nil {
+	rsaPub, ok := pub.(*rsa.PublicKey)
+	if !ok {
+		return nil, errors.New("public key is not a RSA key")
+	}
+
+	if err := verifySignedHeaders(req, version, rsaPub); err != nil {
 		return nil, err
 	}
 

routers/api/packages/chef/chef.go

@@ -71,7 +71,7 @@ func PackagesUniverse(ctx *context.Context) {
 			LocationType: "opscode",
 			LocationPath: baseURL,
 			DownloadURL:  fmt.Sprintf("%s/cookbooks/%s/versions/%s/download", baseURL, url.PathEscape(pd.Package.Name), pd.Version.Version),
-			Dependencies: pd.Metadata.(*chef_module.Metadata).Dependencies,
+			Dependencies: packages_model.DescriptorMetadata[*chef_module.Metadata](pd).Dependencies,
 		}
 	}
 
@@ -128,7 +128,7 @@ func EnumeratePackages(ctx *context.Context) {
 
 	items := make([]*Item, 0, len(pds))
 	for _, pd := range pds {
-		metadata := pd.Metadata.(*chef_module.Metadata)
+		metadata := packages_model.DescriptorMetadata[*chef_module.Metadata](pd)
 
 		items = append(items, &Item{
 			CookbookName:        pd.Package.Name,
@@ -193,7 +193,7 @@ func PackageMetadata(ctx *context.Context) {
 
 	latest := pds[len(pds)-1]
 
-	metadata := latest.Metadata.(*chef_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*chef_module.Metadata](latest)
 
 	ctx.JSON(http.StatusOK, &Result{
 		Name:          latest.Package.Name,
@@ -241,7 +241,7 @@ func PackageVersionMetadata(ctx *context.Context) {
 
 	baseURL := fmt.Sprintf("%sapi/packages/%s/chef/api/v1/cookbooks/%s", setting.AppURL, ctx.Package.Owner.Name, url.PathEscape(pd.Package.Name))
 
-	metadata := pd.Metadata.(*chef_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*chef_module.Metadata](pd)
 
 	ctx.JSON(http.StatusOK, &Result{
 		Version:         pd.Version.Version,

routers/api/packages/composer/api.go

@@ -50,7 +50,7 @@ func createSearchResultResponse(total int64, pds []*packages_model.PackageDescri
 	for _, pd := range pds {
 		results = append(results, &SearchResult{
 			Name:        pd.Package.Name,
-			Description: pd.Metadata.(*composer_module.Metadata).Description,
+			Description: packages_model.DescriptorMetadata[*composer_module.Metadata](pd).Description,
 			Downloads:   pd.Version.DownloadCount,
 		})
 	}
@@ -111,7 +111,7 @@ func createPackageMetadataResponse(ctx *context.Context, registryURL string, pds
 			Version:  pd.Version.Version,
 			Type:     packageType,
 			Created:  pd.Version.CreatedUnix.AsLocalTime(),
-			Metadata: pd.Metadata.(*composer_module.Metadata),
+			Metadata: packages_model.DescriptorMetadata[*composer_module.Metadata](pd),
 			Dist: Dist{
 				Type:     "zip",
 				URL:      fmt.Sprintf("%s/files/%s/%s/%s", registryURL, url.PathEscape(pd.Package.LowerName), url.PathEscape(pd.Version.LowerVersion), url.PathEscape(pd.Files[0].File.LowerName)),

routers/api/packages/conan/conan.go

@@ -103,6 +103,14 @@ func ExtractPathParameters(ctx *context.Context) {
 	ctx.Data[packageReferenceKey] = pref
 }
 
+func getRecipeReference(ctx *context.Context) *conan_module.RecipeReference {
+	return ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference) //nolint:forcetypeassert // must be valid
+}
+
+func getPackageReference(ctx *context.Context) *conan_module.PackageReference {
+	return ctx.Data[packageReferenceKey].(*conan_module.PackageReference) //nolint:forcetypeassert // must be valid
+}
+
 // Ping reports the server capabilities
 func Ping(ctx *context.Context) {
 	ctx.RespHeader().Add("X-Conan-Server-Capabilities", "revisions") // complex_search,checksum_deploy,matrix_params
@@ -164,20 +172,20 @@ func CheckCredentials(ctx *context.Context) {
 
 // RecipeSnapshot displays the recipe files with their md5 hash
 func RecipeSnapshot(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	serveSnapshot(ctx, rref.AsKey())
 }
 
 // RecipeSnapshot displays the package files with their md5 hash
 func PackageSnapshot(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	serveSnapshot(ctx, pref.AsKey())
 }
 
 func serveSnapshot(ctx *context.Context, fileKey string) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	pv, err := packages_model.GetVersionByNameAndVersion(ctx, ctx.Package.Owner.ID, packages_model.TypeConan, rref.Name, rref.Version)
 	if err != nil {
@@ -217,7 +225,7 @@ func serveSnapshot(ctx *context.Context, fileKey string) {
 
 // RecipeDownloadURLs displays the recipe files with their download url
 func RecipeDownloadURLs(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	serveDownloadURLs(
 		ctx,
@@ -228,7 +236,7 @@ func RecipeDownloadURLs(ctx *context.Context) {
 
 // PackageDownloadURLs displays the package files with their download url
 func PackageDownloadURLs(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	serveDownloadURLs(
 		ctx,
@@ -238,7 +246,7 @@ func PackageDownloadURLs(ctx *context.Context) {
 }
 
 func serveDownloadURLs(ctx *context.Context, fileKey, downloadURL string) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	pv, err := packages_model.GetVersionByNameAndVersion(ctx, ctx.Package.Owner.ID, packages_model.TypeConan, rref.Name, rref.Version)
 	if err != nil {
@@ -274,7 +282,7 @@ func serveDownloadURLs(ctx *context.Context, fileKey, downloadURL string) {
 
 // RecipeUploadURLs displays the upload urls for the provided recipe files
 func RecipeUploadURLs(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	serveUploadURLs(
 		ctx,
@@ -285,7 +293,7 @@ func RecipeUploadURLs(ctx *context.Context) {
 
 // PackageUploadURLs displays the upload urls for the provided package files
 func PackageUploadURLs(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	serveUploadURLs(
 		ctx,
@@ -315,21 +323,21 @@ func serveUploadURLs(ctx *context.Context, fileFilter container.Set[string], upl
 
 // UploadRecipeFile handles the upload of a recipe file
 func UploadRecipeFile(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	uploadFile(ctx, recipeFileList, rref.AsKey())
 }
 
 // UploadPackageFile handles the upload of a package file
 func UploadPackageFile(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	uploadFile(ctx, packageFileList, pref.AsKey())
 }
 
 func uploadFile(ctx *context.Context, fileFilter container.Set[string], fileKey string) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	rref := getRecipeReference(ctx)
+	pref := getPackageReference(ctx)
 
 	filename := ctx.PathParam("filename")
 	if !fileFilter.Contains(filename) {
@@ -454,20 +462,20 @@ func uploadFile(ctx *context.Context, fileFilter container.Set[string], fileKey
 
 // DownloadRecipeFile serves the content of the requested recipe file
 func DownloadRecipeFile(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	downloadFile(ctx, recipeFileList, rref.AsKey())
 }
 
 // DownloadPackageFile serves the content of the requested package file
 func DownloadPackageFile(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	downloadFile(ctx, packageFileList, pref.AsKey())
 }
 
 func downloadFile(ctx *context.Context, fileFilter container.Set[string], fileKey string) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	filename := ctx.PathParam("filename")
 	if !fileFilter.Contains(filename) {
@@ -503,7 +511,7 @@ func downloadFile(ctx *context.Context, fileFilter container.Set[string], fileKe
 
 // DeleteRecipeV1 deletes the requested recipe(s)
 func DeleteRecipeV1(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	if err := deleteRecipeOrPackage(ctx, rref, true, nil, false); err != nil {
 		if errors.Is(err, packages_model.ErrPackageNotExist) || errors.Is(err, conan_model.ErrPackageReferenceNotExist) {
@@ -518,7 +526,7 @@ func DeleteRecipeV1(ctx *context.Context) {
 
 // DeleteRecipeV2 deletes the requested recipe(s) respecting its revisions
 func DeleteRecipeV2(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	if err := deleteRecipeOrPackage(ctx, rref, rref.Revision == "", nil, false); err != nil {
 		if errors.Is(err, packages_model.ErrPackageNotExist) || errors.Is(err, conan_model.ErrPackageReferenceNotExist) {
@@ -533,7 +541,7 @@ func DeleteRecipeV2(ctx *context.Context) {
 
 // DeletePackageV1 deletes the requested package(s)
 func DeletePackageV1(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	type PackageReferences struct {
 		References []string `json:"package_ids"`
@@ -582,8 +590,8 @@ func DeletePackageV1(ctx *context.Context) {
 
 // DeletePackageV2 deletes the requested package(s) respecting its revisions
 func DeletePackageV2(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	rref := getRecipeReference(ctx)
+	pref := getPackageReference(ctx)
 
 	if pref != nil { // has package reference
 		if err := deleteRecipeOrPackage(ctx, rref, false, pref, pref.Revision == ""); err != nil {
@@ -693,7 +701,7 @@ func deleteRecipeOrPackage(apictx *context.Context, rref *conan_module.RecipeRef
 
 // ListRecipeRevisions gets a list of all recipe revisions
 func ListRecipeRevisions(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	revisions, err := conan_model.GetRecipeRevisions(ctx, ctx.Package.Owner.ID, rref)
 	if err != nil {
@@ -706,7 +714,7 @@ func ListRecipeRevisions(ctx *context.Context) {
 
 // ListPackageRevisions gets a list of all package revisions
 func ListPackageRevisions(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	revisions, err := conan_model.GetPackageRevisions(ctx, ctx.Package.Owner.ID, pref)
 	if err != nil {
@@ -742,7 +750,7 @@ func listRevisions(ctx *context.Context, revisions []*conan_model.PropertyValue)
 
 // LatestRecipeRevision gets the latest recipe revision
 func LatestRecipeRevision(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	revision, err := conan_model.GetLastRecipeRevision(ctx, ctx.Package.Owner.ID, rref)
 	if err != nil {
@@ -759,7 +767,7 @@ func LatestRecipeRevision(ctx *context.Context) {
 
 // LatestPackageRevision gets the latest package revision
 func LatestPackageRevision(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	revision, err := conan_model.GetLastPackageRevision(ctx, ctx.Package.Owner.ID, pref)
 	if err != nil {
@@ -776,20 +784,20 @@ func LatestPackageRevision(ctx *context.Context) {
 
 // ListRecipeRevisionFiles gets a list of all recipe revision files
 func ListRecipeRevisionFiles(ctx *context.Context) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	listRevisionFiles(ctx, rref.AsKey())
 }
 
 // ListPackageRevisionFiles gets a list of all package revision files
 func ListPackageRevisionFiles(ctx *context.Context) {
-	pref := ctx.Data[packageReferenceKey].(*conan_module.PackageReference)
+	pref := getPackageReference(ctx)
 
 	listRevisionFiles(ctx, pref.AsKey())
 }
 
 func listRevisionFiles(ctx *context.Context, fileKey string) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	pv, err := packages_model.GetVersionByNameAndVersion(ctx, ctx.Package.Owner.ID, packages_model.TypeConan, rref.Name, rref.Version)
 	if err != nil {

routers/api/packages/conan/search.go

@@ -72,7 +72,7 @@ func SearchPackagesV2(ctx *context.Context) {
 }
 
 func searchPackages(ctx *context.Context, searchAllRevisions bool) {
-	rref := ctx.Data[recipeReferenceKey].(*conan_module.RecipeReference)
+	rref := getRecipeReference(ctx)
 
 	if !searchAllRevisions && rref.Revision == "" {
 		lastRevision, err := conan_model.GetLastRecipeRevision(ctx, ctx.Package.Owner.ID, rref)

routers/api/packages/conda/conda.go

@@ -138,7 +138,7 @@ func EnumeratePackages(ctx *context.Context) {
 			return
 		}
 
-		versionMetadata := pd.Metadata.(*conda_module.VersionMetadata)
+		versionMetadata := packages_model.DescriptorMetadata[*conda_module.VersionMetadata](pd)
 
 		pi := &PackageInfo{
 			Name:          pd.PackageProperties.GetByName(conda_module.PropertyName),

routers/api/packages/cran/cran.go

@@ -93,7 +93,7 @@ func enumeratePackages(ctx *context.Context, format string, opts *cran_model.Sea
 			}
 		}
 
-		metadata := pd.Metadata.(*cran_module.Metadata)
+		metadata := packages_model.DescriptorMetadata[*cran_module.Metadata](pd)
 
 		fmt.Fprintln(w, "Package:", pd.Package.Name)
 		fmt.Fprintln(w, "Version:", pd.Version.Version)

routers/api/packages/npm/api.go

@@ -45,7 +45,7 @@ func createPackageMetadataResponse(registryURL string, pds []*packages_model.Pac
 
 	latest := pds[len(pds)-1]
 
-	metadata := latest.Metadata.(*npm_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*npm_module.Metadata](latest)
 
 	return &npm_module.PackageMetadata{
 		ID:          latest.Package.Name,
@@ -67,7 +67,7 @@ func createPackageMetadataResponse(registryURL string, pds []*packages_model.Pac
 func createPackageMetadataVersion(registryURL string, pd *packages_model.PackageDescriptor) *npm_module.PackageMetadataVersion {
 	hashBytes, _ := hex.DecodeString(pd.Files[0].Blob.HashSHA512)
 
-	metadata := pd.Metadata.(*npm_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*npm_module.Metadata](pd)
 
 	return &npm_module.PackageMetadataVersion{
 		ID:                   fmt.Sprintf("%s@%s", pd.Package.Name, pd.Version.Version),
@@ -107,7 +107,7 @@ func createPackageMetadataVersion(registryURL string, pd *packages_model.Package
 func createPackageSearchResponse(pds []*packages_model.PackageDescriptor, total int64) *npm_module.PackageSearch {
 	objects := make([]*npm_module.PackageSearchObject, 0, len(pds))
 	for _, pd := range pds {
-		metadata := pd.Metadata.(*npm_module.Metadata)
+		metadata := packages_model.DescriptorMetadata[*npm_module.Metadata](pd)
 
 		scope := metadata.Scope
 		if scope == "" {

routers/api/packages/nuget/api_v2.go

@@ -332,12 +332,8 @@ func createFeedResponse(l *linkBuilder, totalEntries int64, pds []*packages_mode
 	}
 }
 
-func createEntryResponse(l *linkBuilder, pd *packages_model.PackageDescriptor) *FeedEntry {
-	return createEntry(l, pd, true)
-}
-
 func createEntry(l *linkBuilder, pd *packages_model.PackageDescriptor, withNamespace bool) *FeedEntry {
-	metadata := pd.Metadata.(*nuget_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*nuget_module.Metadata](pd)
 
 	id := l.GetPackageMetadataURL(pd.Package.Name, pd.Version.Version)
 

routers/api/packages/nuget/api_v3.go

@@ -111,7 +111,7 @@ func createRegistrationIndexResponse(l *linkBuilder, pds []*packages_model.Packa
 }
 
 func createRegistrationIndexPageItem(l *linkBuilder, pd *packages_model.PackageDescriptor) *RegistrationIndexPageItem {
-	metadata := pd.Metadata.(*nuget_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*nuget_module.Metadata](pd)
 
 	return &RegistrationIndexPageItem{
 		RegistrationLeafURL: l.GetRegistrationLeafURL(pd.Package.Name, pd.Version.Version),
@@ -120,7 +120,7 @@ func createRegistrationIndexPageItem(l *linkBuilder, pd *packages_model.PackageD
 			CatalogLeafURL:           l.GetRegistrationLeafURL(pd.Package.Name, pd.Version.Version),
 			Authors:                  metadata.Authors,
 			Copyright:                metadata.Copyright,
-			DependencyGroups:         createDependencyGroups(pd),
+			DependencyGroups:         createDependencyGroups(metadata),
 			Description:              metadata.Description,
 			IconURL:                  metadata.IconURL,
 			ID:                       pd.Package.Name,
@@ -139,9 +139,7 @@ func createRegistrationIndexPageItem(l *linkBuilder, pd *packages_model.PackageD
 	}
 }
 
-func createDependencyGroups(pd *packages_model.PackageDescriptor) []*PackageDependencyGroup {
-	metadata := pd.Metadata.(*nuget_module.Metadata)
-
+func createDependencyGroups(metadata *nuget_module.Metadata) []*PackageDependencyGroup {
 	dependencyGroups := make([]*PackageDependencyGroup, 0, len(metadata.Dependencies))
 	for k, v := range metadata.Dependencies {
 		dependencies := make([]*PackageDependency, 0, len(v))
@@ -172,7 +170,7 @@ type RegistrationLeafResponse struct {
 func createRegistrationLeafResponse(l *linkBuilder, pd *packages_model.PackageDescriptor) *RegistrationLeafResponse {
 	registrationLeafURL := l.GetRegistrationLeafURL(pd.Package.Name, pd.Version.Version)
 	packageDownloadURL := l.GetPackageDownloadURL(pd.Package.Name, pd.Version.Version)
-	metadata := pd.Metadata.(*nuget_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*nuget_module.Metadata](pd)
 	return &RegistrationLeafResponse{
 		RegistrationLeafURL:  registrationLeafURL,
 		RegistrationIndexURL: l.GetRegistrationIndexURL(pd.Package.Name),
@@ -182,7 +180,7 @@ func createRegistrationLeafResponse(l *linkBuilder, pd *packages_model.PackageDe
 			CatalogLeafURL:           registrationLeafURL,
 			Authors:                  metadata.Authors,
 			Copyright:                metadata.Copyright,
-			DependencyGroups:         createDependencyGroups(pd),
+			DependencyGroups:         createDependencyGroups(metadata),
 			Description:              metadata.Description,
 			IconURL:                  metadata.IconURL,
 			ID:                       pd.Package.Name,
@@ -290,13 +288,13 @@ func createSearchResult(l *linkBuilder, pds []*packages_model.PackageDescriptor)
 		})
 	}
 
-	metadata := latest.Metadata.(*nuget_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*nuget_module.Metadata](latest)
 
 	return &SearchResult{
 		Authors:                  metadata.Authors,
 		Copyright:                metadata.Copyright,
 		Description:              metadata.Description,
-		DependencyGroups:         createDependencyGroups(latest),
+		DependencyGroups:         createDependencyGroups(metadata),
 		IconURL:                  metadata.IconURL,
 		ID:                       latest.Package.Name,
 		IsPrerelease:             latest.Version.IsPrerelease(),

routers/api/packages/nuget/nuget.go

@@ -267,9 +267,10 @@ func RegistrationLeafV2(ctx *context.Context) {
 		return
 	}
 
-	resp := createEntryResponse(
+	resp := createEntry(
 		&linkBuilder{Base: setting.AppURL + "api/packages/" + ctx.Package.Owner.Name + "/nuget"},
 		pd,
+		true,
 	)
 
 	xmlResponse(ctx, http.StatusOK, resp)

routers/api/packages/pub/pub.go

@@ -67,7 +67,7 @@ func packageDescriptorToMetadata(baseURL string, pd *packages_model.PackageDescr
 		Version:    pd.Version.Version,
 		ArchiveURL: fmt.Sprintf("%s/files/%s.tar.gz", baseURL, url.PathEscape(pd.Version.Version)),
 		Published:  pd.Version.CreatedUnix.AsLocalTime(),
-		Pubspec:    pd.Metadata.(*pub_module.Metadata).Pubspec,
+		Pubspec:    packages_model.DescriptorMetadata[*pub_module.Metadata](pd).Pubspec,
 	}
 }
 

routers/api/packages/rubygems/rubygems.go

@@ -75,7 +75,7 @@ func enumeratePackages(ctx *context.Context, filename string, pvs []*packages_mo
 				Name:  "Gem::Version",
 				Value: []string{p.Version.Version},
 			},
-			p.Metadata.(*rubygems_module.Metadata).Platform,
+			packages_model.DescriptorMetadata[*rubygems_module.Metadata](p).Platform,
 		})
 	}
 
@@ -126,7 +126,7 @@ func ServePackageSpecification(ctx *context.Context) {
 	zw := zlib.NewWriter(ctx.Resp)
 	defer zw.Close()
 
-	metadata := pd.Metadata.(*rubygems_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*rubygems_module.Metadata](pd)
 
 	// create a Ruby Gem::Specification object
 	spec := &rubygems_module.RubyUserDef{
@@ -405,7 +405,7 @@ func makePackageVersionDependency(ctx *context.Context, version *packages_model.
 		return "", err
 	}
 
-	metadata := pd.Metadata.(*rubygems_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*rubygems_module.Metadata](pd)
 	fullFilename := makeGemFullFileName(pd.Package.Name, version.Version, metadata.Platform)
 	file, err := packages_model.GetFileForVersionByName(ctx, version.ID, fullFilename, "")
 	if err != nil {

routers/api/packages/swift/swift.go

@@ -197,7 +197,7 @@ func PackageVersionMetadata(ctx *context.Context) {
 		return
 	}
 
-	metadata := pd.Metadata.(*swift_module.Metadata)
+	metadata := packages_model.DescriptorMetadata[*swift_module.Metadata](pd)
 	repositoryURLs := make([]string, 0, len(pd.VersionProperties))
 	for _, property := range pd.VersionProperties {
 		if property.Name == swift_module.PropertyRepositoryURL {
@@ -278,7 +278,7 @@ func DownloadManifest(ctx *context.Context) {
 			swiftVersion = swift_module.TrimmedVersionString(v)
 		}
 	}
-	m, ok := pd.Metadata.(*swift_module.Metadata).Manifests[swiftVersion]
+	m, ok := packages_model.DescriptorMetadata[*swift_module.Metadata](pd).Manifests[swiftVersion]
 	if !ok {
 		setResponseHeaders(ctx.Resp, &headers{
 			Status:   http.StatusSeeOther,

routers/api/packages/vagrant/vagrant.go

@@ -130,7 +130,7 @@ func EnumeratePackageVersions(ctx *context.Context) {
 
 	ctx.JSON(http.StatusOK, &packageMetadata{
 		Name:        pds[0].Package.Name,
-		Description: pds[len(pds)-1].Metadata.(*vagrant_module.Metadata).Description,
+		Description: packages_model.DescriptorMetadata[*vagrant_module.Metadata](pds[len(pds)-1]).Description,
 		Versions:    versions,
 	})
 }