Add unused markings to suppress warnings.

trunk clang is a bit more aggressive about emitting unused-declaration
warnings, so adjust some AST code to match.  Specifically, use
LLVM_ATTRIBUTE_UNUSED for declarations which are never supposed to be
referenced, and turn references to declarations which are supposed to be
referenced into odr-uses.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@190443 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/Comment.cpp

@@ -42,14 +42,16 @@ good implements_child_begin_end(Comment::child_iterator (T::*)() const) {
   return good();
 }
 
+LLVM_ATTRIBUTE_UNUSED
 static inline bad implements_child_begin_end(
                       Comment::child_iterator (Comment::*)() const) {
   return bad();
 }
 
 #define ASSERT_IMPLEMENTS_child_begin(function) \
-  (void) sizeof(good(implements_child_begin_end(function)))
+  (void) good(implements_child_begin_end(function))
 
+LLVM_ATTRIBUTE_UNUSED
 static inline void CheckCommentASTNodes() {
 #define ABSTRACT_COMMENT(COMMENT)
 #define COMMENT(CLASS, PARENT) \

lib/AST/Stmt.cpp

@@ -135,6 +135,7 @@ namespace {
   template <class T> good implements_children(children_t T::*) {
     return good();
   }
+  LLVM_ATTRIBUTE_UNUSED
   static inline bad implements_children(children_t Stmt::*) {
     return bad();
   }
@@ -143,6 +144,7 @@ namespace {
   template <class T> good implements_getLocStart(getLocStart_t T::*) {
     return good();
   }
+  LLVM_ATTRIBUTE_UNUSED
   static inline bad implements_getLocStart(getLocStart_t Stmt::*) {
     return bad();
   }
@@ -151,20 +153,22 @@ namespace {
   template <class T> good implements_getLocEnd(getLocEnd_t T::*) {
     return good();
   }
+  LLVM_ATTRIBUTE_UNUSED
   static inline bad implements_getLocEnd(getLocEnd_t Stmt::*) {
     return bad();
   }
 
 #define ASSERT_IMPLEMENTS_children(type) \
-  (void) sizeof(is_good(implements_children(&type::children)))
+  (void) is_good(implements_children(&type::children))
 #define ASSERT_IMPLEMENTS_getLocStart(type) \
-  (void) sizeof(is_good(implements_getLocStart(&type::getLocStart)))
+  (void) is_good(implements_getLocStart(&type::getLocStart))
 #define ASSERT_IMPLEMENTS_getLocEnd(type) \
-  (void) sizeof(is_good(implements_getLocEnd(&type::getLocEnd)))
+  (void) is_good(implements_getLocEnd(&type::getLocEnd))
 }
 
 /// Check whether the various Stmt classes implement their member
 /// functions.
+LLVM_ATTRIBUTE_UNUSED
 static inline void check_implementations() {
 #define ABSTRACT_STMT(type)
 #define STMT(type, base) \