1 files changed, 94 insertions, 0 deletions
diff --git a/test/SemaCXX/warn-unused-comparison.cpp b/test/SemaCXX/warn-unused-comparison.cpp
new file mode 100644
index 000000000000..0153f213ba1f
--- /dev/null
+++ b/test/SemaCXX/warn-unused-comparison.cpp
@@ -0,0 +1,94 @@
+// RUN: %clang_cc1 -fsyntax-only -fcxx-exceptions -verify -Wno-unused -Wunused-comparison %s
+
+struct A {
+  bool operator==(const A&);
+  bool operator!=(const A&);
+  A operator|=(const A&);
+  operator bool();
+};
+
+void test() {
+  int x, *p;
+  A a, b;
+
+  x == 7; // expected-warning {{equality comparison result unused}} \
+          // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  x != 7; // expected-warning {{inequality comparison result unused}} \
+          // expected-note {{use '|=' to turn this inequality comparison into an or-assignment}}
+  7 == x; // expected-warning {{equality comparison result unused}}
+  p == p; // expected-warning {{equality comparison result unused}} \
+          // expected-note {{use '=' to turn this equality comparison into an assignment}} \
+          // expected-warning {{self-comparison always evaluates to true}}
+  a == a; // expected-warning {{equality comparison result unused}} \
+          // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  a == b; // expected-warning {{equality comparison result unused}} \
+          // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  a != b; // expected-warning {{inequality comparison result unused}} \
+          // expected-note {{use '|=' to turn this inequality comparison into an or-assignment}}
+  A() == b; // expected-warning {{equality comparison result unused}}
+  if (42) x == 7; // expected-warning {{equality comparison result unused}} \
+                  // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  else if (42) x == 7; // expected-warning {{equality comparison result unused}} \
+                       // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  else x == 7; // expected-warning {{equality comparison result unused}} \
+               // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  do x == 7; // expected-warning {{equality comparison result unused}} \
+             // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  while (false);
+  while (false) x == 7; // expected-warning {{equality comparison result unused}} \
+                        // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  for (x == 7; // expected-warning {{equality comparison result unused}} \
+               // expected-note {{use '=' to turn this equality comparison into an assignment}}
+       x == 7; // No warning -- result is used
+       x == 7) // expected-warning {{equality comparison result unused}} \
+               // expected-note {{use '=' to turn this equality comparison into an assignment}}
+    x == 7; // expected-warning {{equality comparison result unused}} \
+            // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  switch (42) default: x == 7; // expected-warning {{equality comparison result unused}} \
+                               // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  switch (42) case 42: x == 7; // expected-warning {{equality comparison result unused}} \
+                               // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  switch (42) {
+    case 1:
+    case 2:
+    default:
+    case 3:
+    case 4:
+      x == 7; // expected-warning {{equality comparison result unused}} \
+              // expected-note {{use '=' to turn this equality comparison into an assignment}}
+  }
+
+  (void)(x == 7);
+  (void)(p == p); // expected-warning {{self-comparison always evaluates to true}}
+  { bool b = x == 7; }
+
+  { bool b = ({ x == 7; // expected-warning {{equality comparison result unused}} \
+                        // expected-note {{use '=' to turn this equality comparison into an assignment}}
+                x == 7; }); } // no warning on the second, its result is used!
+
+#define EQ(x,y) (x) == (y)
+  EQ(x, 5);
+#undef EQ
+}
+
+namespace PR10291 {
+  template<typename T>
+  class X
+  {
+  public:
+
+    X() : i(0) { } 
+
+    void foo()
+    {   
+      throw 
+        i == 0u ?
+        5 : 6;
+    }   
+
+  private:
+    int i;
+  };
+
+  X<int> x;
+}