[SyntaxParse] Fix round-trip issue in tuple type parsing

Author: rintaro

lib/Parse/ParseType.cpp

@@ -1094,6 +1094,8 @@ Parser::TypeResult Parser::parseTypeTupleBody() {
       } else {
         if (!Backtracking)
           diagnose(Tok, diag::expected_parameter_colon);
+        NameLoc = SourceLoc();
+        SecondNameLoc = SourceLoc();
       }
     } else if (InOut) {
       // If we don't have labels, 'inout' is not a obsoleted use.

test/Syntax/round_trip_misc.swift

@@ -5,14 +5,20 @@ class C {
   typealias Inner: Foo = Int
 
   typealias Alias1 = [Generic<Int
-  typealias Alias2 = () -> (a b: [Generic<Int
+
 
   // Implict accessor with attribute at the top of its body.
   var x: Int {
     @objc
     func f() {}
   }
 }
+do {
+  typealias Alias2 = () -> (a b: [Generic<Int
+}
+do {
+  typealias Alias3 = (a b C, 
+}
 
 // Orphan '}' at top level
 }