Add support for package visibility modifier

Author: gjcairo

Documentation/PLUGIN.md

@@ -124,6 +124,8 @@ The possible values for `Visibility` are:
 
 * `Internal` (default): No visibility is set for the types, so they get the
   default internal visibility.
+* `Package` (Swift 5.9 or later required): The visibility on the types is set to
+ `package` so the types will be exposed across the whole Swift package they belong to.
 * `Public`: The visibility on the types is set to `public` so the types will
   be exposed outside the module they are compiled into.
 

Plugins/SwiftProtobufPlugin/plugin.swift

@@ -37,13 +37,18 @@ struct SwiftProtobufPlugin {
                 case `internal` = "Internal"
                 /// The generated files should have `public` access level.
                 case `public` = "Public"
+                /// The generated files should have `package` access level.
+                /// - Note: Swift 5.9 or later is needed to use this option.
+                case `package` = "Package"
 
                 init?(rawValue: String) {
                     switch rawValue.lowercased() {
                     case "internal":
                         self = .internal
                     case "public":
                         self = .public
+                    case "package":
+                        self = .package
                     default:
                         return nil
                     }

Sources/protoc-gen-swift/GeneratorOptions.swift

@@ -33,13 +33,16 @@ class GeneratorOptions {
   enum Visibility {
     case `internal`
     case `public`
+    case `package`
 
     init?(flag: String) {
       switch flag.lowercased() {
       case "internal":
         self = .internal
       case "public":
         self = .public
+      case "package":
+        self = .package
       default:
         return nil
       }
@@ -119,6 +122,8 @@ class GeneratorOptions {
       visibilitySourceSnippet = ""
     case .public:
       visibilitySourceSnippet = "public "
+    case .package:
+      visibilitySourceSnippet = "package "
     }
 
     self.implementationOnlyImports = implementationOnlyImports