1 files changed, 117 insertions, 0 deletions
diff --git a/test/SemaCXX/warn-self-assign-field-builtin.cpp b/test/SemaCXX/warn-self-assign-field-builtin.cpp
new file mode 100644
index 000000000000..7ae07e7de672
--- /dev/null
+++ b/test/SemaCXX/warn-self-assign-field-builtin.cpp
@@ -0,0 +1,117 @@
+// RUN: %clang_cc1 -fsyntax-only -Wself-assign-field -verify %s
+
+struct C {
+  int a;
+  int b;
+
+  void f() {
+    a = a; // expected-warning {{assigning field to itself}}
+    b = b; // expected-warning {{assigning field to itself}}
+    a = b;
+
+    this->a = a;       // expected-warning {{assigning field to itself}}
+    this->b = b;       // expected-warning {{assigning field to itself}}
+    a = this->a;       // expected-warning {{assigning field to itself}}
+    b = this->b;       // expected-warning {{assigning field to itself}}
+    this->a = this->a; // expected-warning {{assigning field to itself}}
+    this->b = this->b; // expected-warning {{assigning field to itself}}
+
+    a = b;
+    a = this->b;
+    this->a = b;
+    this->a = this->b;
+
+    a *= a;
+    a /= a;
+    a %= a;
+    a += a;
+    a -= a;
+    a <<= a;
+    a >>= a;
+    a &= a;
+    a |= a;
+    a ^= a;
+  }
+
+  void false_positives() {
+#define OP =
+#define LHS a
+#define RHS a
+    // These shouldn't warn due to the use of the preprocessor.
+    a OP a;
+    LHS = a;
+    a = RHS;
+    LHS OP RHS;
+#undef OP
+#undef LHS
+#undef RHS
+
+    // A way to silence the warning.
+    a = (int &)a;
+  }
+
+  // Do not diagnose self-assigment in an unevaluated context
+  void false_positives_unevaluated_ctx() noexcept(noexcept(a = a)) // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+  {
+    decltype(a = a) b = a;              // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+    static_assert(noexcept(a = a), ""); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+    static_assert(sizeof(a = a), "");   // expected-warning {{expression with side effects has no effect in an unevaluated context}}
+  }
+
+  volatile int vol_a;
+  void vol_test() {
+    // Volatile stores aren't side-effect free.
+    vol_a = vol_a;
+    volatile int &vol_a_ref = vol_a;
+    vol_a_ref = vol_a_ref;
+  }
+};
+
+// Dummy type.
+struct Dummy {};
+
+template <typename T>
+struct TemplateClass {
+  T var;
+  void f() {
+    var = var; // expected-warning {{assigning field to itself}}
+  }
+};
+void instantiate() {
+  {
+    TemplateClass<int> c;
+    c.f();
+  }
+  {
+    TemplateClass<Dummy> c;
+    c.f();
+  }
+}
+
+// It may make sense not to warn on the rest of the tests.
+// It may be a valid use-case to self-assign to tell the compiler that
+// it is ok to vectorize the store.
+
+void f0(C *s, C *t) {
+  s->a = s->a;
+  t->a = s->a;
+}
+
+void f1(C &s, C &t) {
+  s.a = s.a;
+  t.a = s.a;
+}
+
+struct T {
+  C *s;
+};
+
+void f2(T *t, T *t2) {
+  t->s->a = t->s->a;
+  t2->s->a = t->s->a;
+}
+
+void f3(T &t, T &t2) {
+  t.s->a = t.s->a;
+  t2.s->a = t.s->a;
+}