feat(internal/config): add RootName to rust module (#3550)

Add `RootName` to rust module config. This param needs to be override
when generating the special protojson-conformance library.

Add the following config in google-cloud-rust after merging this PR:
```
  - name: protojson-conformance
    copyright_year: "2025"
    output: tests/protojson-conformance
    rust:
      modules:
        - include_list: conformance.proto
          module_path: crate::generated::gapic::model
          output: tests/protojson-conformance/src/generated/convert
          source: conformance
          template: convert-prost
        - generate_setter_samples: "false"
          include_list: conformance.proto
          module_path: crate::generated::gapic::model
          output: tests/protojson-conformance/src/generated/gapic
          source: conformance
          template: grpc-client
        - include_list: conformance.proto
          module_path: crate::generated::gapic::model
          output: tests/protojson-conformance/src/generated/protos
          root_name: conformance-root
          source: conformance
          template: prost
        - generate_setter_samples: "false"
          include_list: test_messages_proto3.proto
          module_path: crate::generated::test_protos
          output: tests/protojson-conformance/src/generated/test_protos
          source: src/google/protobuf
          template: mod
    skip_publish: true
    veneer: true
```

Fixes #3533

Author: JoeWang1127

internal/config/language.go

@@ -99,6 +99,10 @@ type RustModule struct {
 	// PostProcessProtos contains code to post-process generated protos.
 	PostProcessProtos string `yaml:"post_process_protos,omitempty"`
 
+	// RootName is the key for the root directory in the source map.
+	// It overrides the default root, googleapis-root, used by the rust+prost generator.
+	RootName string `yaml:"root_name,omitempty"`
+
 	// RoutingRequired indicates whether routing is required.
 	RoutingRequired bool `yaml:"routing_required,omitempty"`
 

internal/librarian/rust/codec.go

@@ -21,7 +21,7 @@ import (
 	sidekickconfig "github.com/googleapis/librarian/internal/sidekick/config"
 )
 
-func toSidekickConfig(library *config.Library, channel *config.Channel, googleapisDir, discoveryDir, protobufRootDir, conformanceDir, showcaseDir string) *sidekickconfig.Config {
+func toSidekickConfig(library *config.Library, channel *config.Channel, sources *Sources) *sidekickconfig.Config {
 	source := map[string]string{}
 	specFormat := "protobuf"
 	if library.SpecificationFormat != "" {
@@ -31,21 +31,21 @@ func toSidekickConfig(library *config.Library, channel *config.Channel, googleap
 		specFormat = "disco"
 	}
 
-	if len(library.Roots) == 0 && googleapisDir != "" {
+	if len(library.Roots) == 0 && sources.Googleapis != "" {
 		// Default to googleapis if no roots are specified.
-		source["googleapis-root"] = googleapisDir
+		source["googleapis-root"] = sources.Googleapis
 		source["roots"] = "googleapis"
 	} else {
 		source["roots"] = strings.Join(library.Roots, ",")
 		rootMap := map[string]struct {
 			path string
 			key  string
 		}{
-			"googleapis":   {path: googleapisDir, key: "googleapis-root"},
-			"discovery":    {path: discoveryDir, key: "discovery-root"},
-			"showcase":     {path: showcaseDir, key: "showcase-root"},
-			"protobuf-src": {path: protobufRootDir, key: "protobuf-src-root"},
-			"conformance":  {path: conformanceDir, key: "conformance-root"},
+			"googleapis":   {path: sources.Googleapis, key: "googleapis-root"},
+			"discovery":    {path: sources.Discovery, key: "discovery-root"},
+			"showcase":     {path: sources.Showcase, key: "showcase-root"},
+			"protobuf-src": {path: sources.ProtobufSrc, key: "protobuf-src-root"},
+			"conformance":  {path: sources.Conformance, key: "conformance-root"},
 		}
 		for _, root := range library.Roots {
 			if r, ok := rootMap[root]; ok && r.path != "" {
@@ -227,10 +227,13 @@ func formatPackageDependency(dep *config.RustPackageDependency) string {
 	return strings.Join(parts, ",")
 }
 
-func moduleToSidekickConfig(library *config.Library, module *config.RustModule, googleapisDir, protobufSrcDir string) *sidekickconfig.Config {
+func moduleToSidekickConfig(library *config.Library, module *config.RustModule, sources *Sources) *sidekickconfig.Config {
 	source := map[string]string{
-		"googleapis-root":   googleapisDir,
-		"protobuf-src-root": protobufSrcDir,
+		"conformance-root":  sources.Conformance,
+		"discovery-root":    sources.Discovery,
+		"googleapis-root":   sources.Googleapis,
+		"protobuf-src-root": sources.ProtobufSrc,
+		"showcase-root":     sources.Showcase,
 	}
 	for root, dir := range module.ModuleRoots {
 		source[root] = dir
@@ -317,6 +320,8 @@ func buildModuleCodec(library *config.Library, module *config.RustModule) map[st
 	if module.DisabledRustdocWarnings != nil {
 		codec["disabled-rustdoc-warnings"] = strings.Join(module.DisabledRustdocWarnings, ",")
 	}
-
+	if module.RootName != "" {
+		codec["root-name"] = module.RootName
+	}
 	return codec
 }

internal/librarian/rust/codec_test.go

@@ -24,15 +24,11 @@ import (
 
 func TestToSidekickConfig(t *testing.T) {
 	for _, test := range []struct {
-		name           string
-		library        *config.Library
-		channel        *config.Channel
-		googleapisDir  string
-		discoveryDir   string
-		protobufDir    string
-		conformanceDir string
-		showcaseDir    string
-		want           *sidekickconfig.Config
+		name    string
+		library *config.Library
+		channel *config.Channel
+		sources *Sources
+		want    *sidekickconfig.Config
 	}{
 		{
 			name: "minimal config",
@@ -43,7 +39,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -72,7 +70,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -102,7 +102,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -146,7 +148,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -188,7 +192,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -229,7 +235,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -265,11 +273,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir:  "/tmp/googleapis",
-			discoveryDir:   "",
-			protobufDir:    "",
-			conformanceDir: "",
-			showcaseDir:    "",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -324,11 +330,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir:  "/tmp/googleapis",
-			discoveryDir:   "",
-			protobufDir:    "",
-			conformanceDir: "",
-			showcaseDir:    "",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -374,11 +378,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storage/v1",
 				ServiceConfig: "google/cloud/storage/v1/storage_v1.yaml",
 			},
-			googleapisDir:  "/tmp/googleapis",
-			discoveryDir:   "",
-			protobufDir:    "",
-			conformanceDir: "",
-			showcaseDir:    "",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -412,8 +414,10 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "discoveries/compute.v1.json",
 				ServiceConfig: "google/cloud/compute/v1/compute_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
-			discoveryDir:  "/tmp/discovery-artifact-manager",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+				Discovery:  "/tmp/discovery-artifact-manager",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -442,9 +446,11 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "discoveries/compute.v1.json",
 				ServiceConfig: "google/cloud/compute/v1/compute_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
-			discoveryDir:  "/tmp/discovery-artifact-manager",
-			showcaseDir:   "/tmp/showcase",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+				Discovery:  "/tmp/discovery-artifact-manager",
+				Showcase:   "/tmp/showcase",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -474,7 +480,9 @@ func TestToSidekickConfig(t *testing.T) {
 			channel: &config.Channel{
 				Path: "google/apps/script/type/gmail",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -501,7 +509,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/longrunning",
 				ServiceConfig: "google/longrunning/longrunning.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -535,7 +545,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/spanner/admin/database/v1",
 				ServiceConfig: "google/spanner/admin/database/v1/spanner.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -565,7 +577,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/storageinsights/v1",
 				ServiceConfig: "google/cloud/storageinsights/v1/storageinsights_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -613,8 +627,10 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "discoveries/compute.v1.json",
 				ServiceConfig: "google/cloud/compute/v1/compute_v1.yaml",
 			},
-			googleapisDir: "/tmp/googleapis",
-			discoveryDir:  "/tmp/discovery-artifact-manager",
+			sources: &Sources{
+				Googleapis: "/tmp/googleapis",
+				Discovery:  "/tmp/discovery-artifact-manager",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -659,9 +675,11 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/cloud/vision/v1",
 				ServiceConfig: "google/cloud/vision/v1/vision_v1.yaml",
 			},
-			googleapisDir:  "/tmp/googleapis",
-			protobufDir:    "/tmp/protobuf/src",
-			conformanceDir: "/tmp/conformance",
+			sources: &Sources{
+				Googleapis:  "/tmp/googleapis",
+				ProtobufSrc: "/tmp/protobuf/src",
+				Conformance: "/tmp/conformance",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -690,7 +708,9 @@ func TestToSidekickConfig(t *testing.T) {
 				Path:          "google/showcase/v1beta1",
 				ServiceConfig: "google/showcase/v1beta1/showcase_v1beta1.yaml",
 			},
-			showcaseDir: "/tmp/gapic-showcase",
+			sources: &Sources{
+				Showcase: "/tmp/gapic-showcase",
+			},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -719,6 +739,7 @@ func TestToSidekickConfig(t *testing.T) {
 					},
 				},
 			},
+			sources: &Sources{},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust_storage",
@@ -738,6 +759,7 @@ func TestToSidekickConfig(t *testing.T) {
 					},
 				},
 			},
+			sources: &Sources{},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language:            "rust",
@@ -757,6 +779,7 @@ func TestToSidekickConfig(t *testing.T) {
 					},
 				},
 			},
+			sources: &Sources{},
 			want: &sidekickconfig.Config{
 				General: sidekickconfig.GeneralConfig{
 					Language: "rust+prost",
@@ -768,14 +791,14 @@ func TestToSidekickConfig(t *testing.T) {
 			if test.library.Rust != nil && test.library.Rust.Modules != nil {
 				var commentOverrides []sidekickconfig.DocumentationOverride
 				for _, module := range test.library.Rust.Modules {
-					got := moduleToSidekickConfig(test.library, module, test.googleapisDir, test.protobufDir)
+					got := moduleToSidekickConfig(test.library, module, test.sources)
 					commentOverrides = append(commentOverrides, got.CommentOverrides...)
 				}
 				if diff := cmp.Diff(test.want.CommentOverrides, commentOverrides); diff != "" {
 					t.Errorf("mismatch (-want +got):\n%s", diff)
 				}
 			} else {
-				got := toSidekickConfig(test.library, test.channel, test.googleapisDir, test.discoveryDir, test.protobufDir, test.conformanceDir, test.showcaseDir)
+				got := toSidekickConfig(test.library, test.channel, test.sources)
 				if diff := cmp.Diff(test.want, got); diff != "" {
 					t.Errorf("mismatch (-want +got):\n%s", diff)
 				}