[Macros] Add notion of owning module and supplemental modules for macros

Sources/_SwiftSyntaxMacros/Macro.swift

@@ -39,11 +39,29 @@ public protocol Macro: _CompilerPlugin {
   /// as `#line`) that does not. This is a syntactic distinction, not a
   /// semantic one.
   static var signature: TypeSyntax { get }
+
+  /// The module that "owns" this macro.
+  ///
+  /// This module must be imported by any code that wishes to use the macro.
+  static var owningModule: String { get }
+
+  /// Additional imports requires to describe the signature of the macro.
+  ///
+  /// For example, if your macro is owned by module A, but its signature also
+  /// contains types from another module B that is used by A, then the module
+  /// B should be
+  static var supplementalSignatureModules: [String] { get }
 }
 
 extension Macro {
   /// Default, empty documentation string for macros.
   public static var documentation: String { "" }
+
+  /// Default, empty set of supplemental signature modules.
+  ///
+  /// Many macros won't need any supplemental signature modules beyond the
+  /// default "Swift" import.
+  public static var supplementalSignatureModules: [String] { [] }
 }
 
 #if canImport(_CompilerPluginSupport)
@@ -77,5 +95,24 @@ extension Macro {
       return (UnsafePointer(result), count: buffer.count)
     }
   }
+
+  public static func _owningModule() -> (UnsafePointer<UInt8>, count: Int) {
+    var module = "\(owningModule)"
+    return module.withUTF8 { buffer in
+      let result = UnsafeMutablePointer<UInt8>.allocate(capacity: buffer.count)
+      result.initialize(from: buffer.baseAddress!, count: buffer.count)
+      return (UnsafePointer(result), count: buffer.count)
+    }
+  }
+
+  public static func _supplementalSignatureModules()
+      -> (UnsafePointer<UInt8>, count: Int) {
+    var allModulesJoined = supplementalSignatureModules.joined(separator:";")
+    return allModulesJoined.withUTF8 { buffer in
+      let result = UnsafeMutablePointer<UInt8>.allocate(capacity: buffer.count)
+      result.initialize(from: buffer.baseAddress!, count: buffer.count)
+      return (UnsafePointer(result), count: buffer.count)
+    }
+  }
 }
 #endif

Sources/_SwiftSyntaxMacros/MacroSystem+Builtin.swift

@@ -27,6 +27,8 @@ struct ColumnMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "T"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -51,6 +53,8 @@ struct LineMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "T"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -87,6 +91,8 @@ struct FunctionMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "T"
 
+  static var owningModule: String = "Swift"
+
   /// Form a function name.
   private static func formFunctionName(
     _ baseName: String, _ parameters: ParameterClauseSyntax?,
@@ -221,6 +227,10 @@ struct ColorLiteralMacro: ExpressionMacro {
      ) -> T
      """
 
+  // FIXME: Not entirely correct, should use _ColorLiteralType from
+  // appropriate place.
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -250,6 +260,8 @@ struct FileLiteralMacro: ExpressionMacro {
   static var signature: TypeSyntax =
       "(resourceName path: String) -> T"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -279,6 +291,9 @@ struct ImageLiteralMacro: ExpressionMacro {
   static var signature: TypeSyntax =
       "(resourceName path: String) -> T"
 
+  // FIXME: Not really correct, use _ImageLiteralType
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -307,6 +322,8 @@ struct FilePathMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "T"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -335,6 +352,8 @@ struct FileIDMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "T"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {
@@ -369,6 +388,8 @@ struct FileMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "T"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {

Sources/_SwiftSyntaxMacros/MacroSystem+Examples.swift

@@ -25,6 +25,8 @@ struct StringifyMacro: ExpressionMacro {
 
   static var signature: TypeSyntax = "(T) -> (T, String)"
 
+  static var owningModule: String = "Swift"
+
   static func apply(
     _ macro: MacroExpansionExprSyntax, in context: MacroEvaluationContext
   ) -> MacroResult<ExprSyntax> {