[Syntax] Add #selector and #keyPath tokens (#13615)

* [Syntax] Add #selector and #keyPath tokens

* [Syntax][test] Add #selector and #keyPath to syntax parsing tests

* [Syntax] Don't fatalError on an unknown token kind

* Fix test build error

Author: harlanhaskins

test/SwiftSyntax/ParseFile.swift

@@ -14,6 +14,18 @@ struct Foo {
   private(set) var y: [Bool]
 }
 
+#if os(macOS)
+class Test: NSObject {
+  @objc var bar: Int = 0
+  func test() {
+    print(#selector(function))
+    print(#keyPath(bar))
+  }
+  @objc func function() {
+  }
+}
+#endif
+
 ParseFile.test("ParseSingleFile") {
   let currentFile = URL(fileURLWithPath: #file)
   expectDoesNotThrow({

tools/SwiftSyntax/TokenKind.swift.gyb

@@ -52,6 +52,10 @@ public enum TokenKind: Codable {
     case kind, text
   }
 
+  enum DecodeError: Error {
+    case unknownTokenKind(String)
+  }
+
   public init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
     let kind = try container.decode(String.self, forKey: .kind)
@@ -67,10 +71,10 @@ public enum TokenKind: Codable {
       self = .${token.swift_kind()}(text)
 %   end
 % end
-    default: fatalError("unknown token kind \(kind)")
+    default: throw DecodeError.unknownTokenKind(kind)
     }
   }
-  
+
   public func encode(to encoder: Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)
     try container.encode(kind, forKey: .kind)

utils/gyb_syntax_support/Token.py

@@ -108,6 +108,10 @@ def __init__(self, name, text):
           is_keyword=True),
     Token('PoundFunction', 'pound_function', text='#function',
           is_keyword=True),
+    Token('PoundSelector', 'pound_selector', text='#selector',
+          is_keyword=True),
+    Token('PoundKeyPath', 'pound_keyPath', text='#keyPath',
+          is_keyword=True),
     Token('Arrow', 'arrow', text='->'),
     Token('AtSign', 'at_sign', text='@'),
     Token('Colon', 'colon', text=':'),