Add comments in both added files

Author: zoecarver

include/swift/Basic/Semantics.def

@@ -10,6 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 //
+// This macro is used to map the global definition name of a semantic attribute to its raw value.
+//   NAME: the global name used in the compiler
+//   C_STR: the raw value used in swift
+//
 // SEMA_ATTR(NAME, C_STR)
 //
 //===----------------------------------------------------------------------===//
@@ -70,17 +74,5 @@ SEMA_ATTR(SLOWPATH, "slowpath")
 SEMA_ATTR(PROGRAMTERMINATION_POINT, "programtermination_point")
 SEMA_ATTR(CONVERT_TO_OBJECTIVE_C, "convertToObjectiveC")
 
-// SEMA_ATTR(, "456")
-// SEMA_ATTR(, "123")
-// SEMA_ATTR(, "223")
-// SEMA_ATTR(, "bar")
-// SEMA_ATTR(, "class")
-// SEMA_ATTR(, "crazy")
-// SEMA_ATTR(, "enum")
-// SEMA_ATTR(, "struct")
-// SEMA_ATTR(, "struct1")
-// SEMA_ATTR(, "struct2")
-// SEMA_ATTR(, "test_driver")
-
 #undef SEMA_ATTR
 

include/swift/Basic/Semantics.h

@@ -1,3 +1,20 @@
+//===--- Semantics.h - Semantics Attribute Definitions -------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation of the matching definition file.
+// This file holds all semantics attributes as consant stirng literals.
+//
+//===----------------------------------------------------------------------===//
+
 #ifndef SWIFT_SEMANTICS_H
 #define SWIFT_SEMANTICS_H