1 files changed, 44 insertions, 0 deletions
diff --git a/test/SemaCXX/warn-unused-value-cxx11.cpp b/test/SemaCXX/warn-unused-value-cxx11.cpp
new file mode 100644
index 000000000000..d929b4fd12fb
--- /dev/null
+++ b/test/SemaCXX/warn-unused-value-cxx11.cpp
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wunused-value %s
+
+void f() __attribute__((const));
+
+namespace PR18571 {
+// Unevaluated contexts should not trigger unused result warnings.
+template <typename T>
+auto foo(T) -> decltype(f(), bool()) { // Should not warn.
+  return true;
+}
+
+void g() {
+  foo(1);
+}
+
+void h() {
+  int i = 0;
+  (void)noexcept(++i); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+  decltype(i++) j = 0; // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+}
+
+struct S {
+  S operator++(int);
+  S(int i);
+  S();
+
+  int& f();
+  S g();
+};
+
+void j() {
+  S s;
+  int i = 0;
+  (void)noexcept(s++); // Ok
+  (void)noexcept(i++); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+  (void)noexcept(i = 5); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+  (void)noexcept(s = 5); // Ok
+
+  (void)sizeof(s.f()); // Ok
+  (void)sizeof(s.f() = 5); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+  (void)noexcept(s.g() = 5); // Ok
+}
+
+}
+\ No newline at end of file