1 files changed, 31 insertions, 3 deletions
diff --git a/test/SemaCXX/warn-unused-value.cpp b/test/SemaCXX/warn-unused-value.cpp
index 4e1347cc307a..efabd5063068 100644
--- a/test/SemaCXX/warn-unused-value.cpp
+++ b/test/SemaCXX/warn-unused-value.cpp
@@ -39,13 +39,13 @@ namespace test2 {
         void method() const {
          X* x;
          &x[0];  // expected-warning {{expression result unused}}
-        }  
+        }
       };
       typedef basic_string<char> string;
-      void func(const std::string& str) { 
+      void func(const std::string& str) {
         str.method();  // expected-note {{in instantiation of member function}}
       }
-    } 
+    }
   }
 }
 
@@ -69,3 +69,31 @@ void f() {
   Unused(1, 1); // expected-warning {{expression result unused}}
 }
 }
+
+namespace std {
+  struct type_info {};
+}
+
+namespace test4 {
+struct Good { Good &f(); };
+struct Bad { virtual Bad& f(); };
+
+void f() {
+  int i = 0;
+  (void)typeid(++i); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+
+  Good g;
+  (void)typeid(g.f()); // Ok; not a polymorphic use of a glvalue.
+
+  // This is a polymorphic use of a glvalue, which results in the typeid being
+  // evaluated instead of unevaluated.
+  Bad b;
+  (void)typeid(b.f()); // expected-warning {{expression with side effects will be evaluated despite being used as an operand to 'typeid'}}
+
+  // A dereference of a volatile pointer is a side effecting operation, however
+  // since it is idiomatic code, and the alternatives induce higher maintenance
+  // costs, it is allowed.
+  int * volatile x;
+  (void)sizeof(*x); // Ok
+}
+}