clang/test/SemaCXX/warn-self-assign-builtin.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -Wself-assign -verify %s
   2
   3 void f() {
   4   int a = 42, b = 42;
   5   a = a; // expected-warning{{explicitly assigning}}
   6   b = b; // expected-warning{{explicitly assigning}}
   7   a = b;
   8   b = a = b;
   9   a = a = a; // expected-warning{{explicitly assigning}}
  10   a = b = b = a;
  11
  12   a *= a;
  13   a /= a;
  14   a %= a;
  15   a += a;
  16   a -= a;
  17   a <<= a;
  18   a >>= a;
  19   a &= a; // expected-warning {{explicitly assigning}}
  20   a |= a; // expected-warning {{explicitly assigning}}
  21   a ^= a;
  22 }
  23
  24 // Dummy type.
  25 struct S {};
  26
  27 void false_positives() {
  28 #define OP =
  29 #define LHS a
  30 #define RHS a
  31   int a = 42;
  32   // These shouldn't warn due to the use of the preprocessor.
  33   a OP a;
  34   LHS = a;
  35   a = RHS;
  36   LHS OP RHS;
  37 #undef OP
  38 #undef LHS
  39 #undef RHS
  40
  41   // A way to silence the warning.
  42   a = (int &)a;
  43
  44   // Volatile stores aren't side-effect free.
  45   volatile int vol_a;
  46   vol_a = vol_a;
  47   volatile int &vol_a_ref = vol_a;
  48   vol_a_ref = vol_a_ref;
  49 }
  50
  51 // Do not diagnose self-assigment in an unevaluated context
  52 void false_positives_unevaluated_ctx(int a) noexcept(noexcept(a = a)) // expected-warning {{expression with side effects has no effect in an unevaluated context}}
  53 {
  54   decltype(a = a) b = a;              // expected-warning {{expression with side effects has no effect in an unevaluated context}}
  55   static_assert(noexcept(a = a), ""); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
  56   static_assert(sizeof(a = a), "");   // expected-warning {{expression with side effects has no effect in an unevaluated context}}
  57 }
  58
  59 template <typename T>
  60 void g() {
  61   T a;
  62   a = a; // expected-warning{{explicitly assigning}}
  63 }
  64 void instantiate() {
  65   g<int>();
  66   g<S>();
  67 }