clang/test/SemaCXX/warn-unused-lambda-capture.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -Wunused-lambda-capture -Wused-but-marked-unused -Wno-uninitialized -verify -std=c++1z %s
   2
   3 class NonTrivialConstructor {
   4 public:
   5   NonTrivialConstructor() {}
   6 };
   7
   8 class NonTrivialCopyConstructor {
   9 public:
  10   NonTrivialCopyConstructor() = default;
  11   NonTrivialCopyConstructor(const NonTrivialCopyConstructor &) {}
  12 };
  13
  14 class NonTrivialDestructor {
  15 public:
  16   ~NonTrivialDestructor() {}
  17 };
  18
  19 class Trivial {
  20 public:
  21   Trivial() = default;
  22   Trivial(int a) {}
  23 };
  24
  25 int side_effect() {
  26   return 42;
  27 }
  28
  29 void test() {
  30   int i = 0;
  31   const int k = 0;
  32
  33   auto captures_nothing = [] {};
  34
  35   auto captures_nothing_by_value = [=] {};
  36   auto captures_nothing_by_reference = [&] {};
  37
  38   auto implicit_by_value = [=]() mutable { i++; };
  39   auto implicit_by_reference = [&] { i++; };
  40
  41   auto explicit_by_value_used = [i] { return i + 1; };
  42   auto explicit_by_value_used_void = [i] { (void)i; };
  43   auto explicit_by_value_unused = [i] {}; // expected-warning{{lambda capture 'i' is not used}}
  44   auto explicit_by_value_unused_sizeof = [i] { return sizeof(i); }; // expected-warning{{lambda capture 'i' is not required to be captured for this use}}
  45   auto explicit_by_value_unused_decltype = [i] { decltype(i) j = 0; }; // expected-warning{{lambda capture 'i' is not required to be captured for this use}}
  46   auto explicit_by_value_unused_const = [k] { return k + 1; };         // expected-warning{{lambda capture 'k' is not required to be captured for this use}}
  47
  48   auto explicit_by_reference_used = [&i] { i++; };
  49   auto explicit_by_reference_unused = [&i] {}; // expected-warning{{lambda capture 'i' is not used}}
  50
  51   auto explicit_initialized_reference_used = [&j = i] { return j + 1; };
  52   auto explicit_initialized_reference_unused = [&j = i]{}; // expected-warning{{lambda capture 'j' is not used}}
  53
  54   auto explicit_initialized_value_used = [j = 1] { return j + 1; };
  55   auto explicit_initialized_value_unused = [j = 1] {}; // expected-warning{{lambda capture 'j' is not used}}
  56   auto explicit_initialized_value_non_trivial_constructor = [j = NonTrivialConstructor()]{};
  57   auto explicit_initialized_value_non_trivial_destructor = [j = NonTrivialDestructor()]{};
  58   auto explicit_initialized_value_trivial_init = [j = Trivial()]{}; // expected-warning{{lambda capture 'j' is not used}}
  59   auto explicit_initialized_value_non_trivial_init = [j = Trivial(42)]{};
  60   auto explicit_initialized_value_with_side_effect = [j = side_effect()]{};
  61
  62   auto nested = [&i] {
  63     auto explicit_by_value_used = [i] { return i + 1; };
  64     auto explicit_by_value_unused = [i] {}; // expected-warning{{lambda capture 'i' is not used}}
  65   };
  66
  67   Trivial trivial;
  68   auto explicit_by_value_trivial = [trivial] {}; // expected-warning{{lambda capture 'trivial' is not used}}
  69
  70   NonTrivialConstructor cons;
  71   auto explicit_by_value_non_trivial_constructor = [cons] {}; // expected-warning{{lambda capture 'cons' is not used}}
  72
  73   NonTrivialCopyConstructor copy_cons;
  74   auto explicit_by_value_non_trivial_copy_constructor = [copy_cons] {};
  75
  76   NonTrivialDestructor dest;
  77   auto explicit_by_value_non_trivial_destructor = [dest] {};
  78
  79   volatile int v;
  80   auto explicit_by_value_volatile = [v] {};
  81 }
  82
  83 class TrivialThis : Trivial {
  84   void test() {
  85     auto explicit_this_used = [this] { return i; };
  86     auto explicit_this_used_void = [this] { (void)this; };
  87     auto explicit_this_unused = [this] {}; // expected-warning{{lambda capture 'this' is not used}}
  88     auto explicit_star_this_used = [*this] { return i; };
  89     auto explicit_star_this_used_void = [*this] { (void)this; };
  90     auto explicit_star_this_unused = [*this] {}; // expected-warning{{lambda capture 'this' is not used}}
  91   }
  92   int i;
  93 };
  94
  95 class NonTrivialConstructorThis : NonTrivialConstructor {
  96   void test() {
  97     auto explicit_this_used = [this] { return i; };
  98     auto explicit_this_used_void = [this] { (void)this; };
  99     auto explicit_this_unused = [this] {}; // expected-warning{{lambda capture 'this' is not used}}
 100     auto explicit_star_this_used = [*this] { return i; };
 101     auto explicit_star_this_used_void = [*this] { (void)this; };
 102     auto explicit_star_this_unused = [*this] {}; // expected-warning{{lambda capture 'this' is not used}}
 103   }
 104   int i;
 105 };
 106
 107 class NonTrivialCopyConstructorThis : NonTrivialCopyConstructor {
 108   void test() {
 109     auto explicit_this_used = [this] { return i; };
 110     auto explicit_this_used_void = [this] { (void)this; };
 111     auto explicit_this_unused = [this] {}; // expected-warning{{lambda capture 'this' is not used}}
 112     auto explicit_star_this_used = [*this] { return i; };
 113     auto explicit_star_this_used_void = [*this] { (void)this; };
 114     auto explicit_star_this_unused = [*this] {};
 115   }
 116   int i;
 117 };
 118
 119 class NonTrivialDestructorThis : NonTrivialDestructor {
 120   void test() {
 121     auto explicit_this_used = [this] { return i; };
 122     auto explicit_this_used_void = [this] { (void)this; };
 123     auto explicit_this_unused = [this] {}; // expected-warning{{lambda capture 'this' is not used}}
 124     auto explicit_star_this_used = [*this] { return i; };
 125     auto explicit_star_this_used_void = [*this] { (void)this; };
 126     auto explicit_star_this_unused = [*this] {};
 127   }
 128   int i;
 129 };
 130
 131 template <typename T>
 132 void test_templated() {
 133   int i = 0;
 134   const int k = 0;
 135
 136   auto captures_nothing = [] {};
 137
 138   auto captures_nothing_by_value = [=] {};
 139   auto captures_nothing_by_reference = [&] {};
 140
 141   auto implicit_by_value = [=]() mutable { i++; };
 142   auto implicit_by_reference = [&] { i++; };
 143
 144   auto explicit_by_value_used = [i] { return i + 1; };
 145   auto explicit_by_value_used_generic = [i](auto c) { return i + 1; };
 146   auto explicit_by_value_used_void = [i] { (void)i; };
 147
 148   auto explicit_by_value_unused = [i] {}; // expected-warning{{lambda capture 'i' is not used}}
 149   auto explicit_by_value_unused_sizeof = [i] { return sizeof(i); }; // expected-warning{{lambda capture 'i' is not required to be captured for this use}}
 150   auto explicit_by_value_unused_decltype = [i] { decltype(i) j = 0; }; // expected-warning{{lambda capture 'i' is not used}}
 151   auto explicit_by_value_unused_const = [k] { return k + 1; };         // expected-warning{{lambda capture 'k' is not required to be captured for this use}}
 152   auto explicit_by_value_unused_const_generic = [k](auto c) { return k + 1; }; // expected-warning{{lambda capture 'k' is not required to be captured for this use}}
 153
 154   auto explicit_by_reference_used = [&i] { i++; };
 155   auto explicit_by_reference_unused = [&i] {}; // expected-warning{{lambda capture 'i' is not used}}
 156
 157   auto explicit_initialized_reference_used = [&j = i] { return j + 1; };
 158   auto explicit_initialized_reference_unused = [&j = i]{}; // expected-warning{{lambda capture 'j' is not used}}
 159
 160   auto explicit_initialized_value_used = [j = 1] { return j + 1; };
 161   auto explicit_initialized_value_unused = [j = 1] {}; // expected-warning{{lambda capture 'j' is not used}}
 162   auto explicit_initialized_value_non_trivial_constructor = [j = NonTrivialConstructor()]{};
 163   auto explicit_initialized_value_non_trivial_destructor = [j = NonTrivialDestructor()]{};
 164   auto explicit_initialized_value_trivial_init = [j = Trivial()]{}; // expected-warning{{lambda capture 'j' is not used}}
 165   auto explicit_initialized_value_non_trivial_init = [j = Trivial(42)]{};
 166   auto explicit_initialized_value_with_side_effect = [j = side_effect()]{};
 167   auto explicit_initialized_value_generic_used = [i = 1](auto c) mutable { i++; };
 168   auto explicit_initialized_value_generic_unused = [i = 1](auto c) mutable {}; // expected-warning{{lambda capture 'i' is not used}}
 169
 170   auto nested = [&i] {
 171     auto explicit_by_value_used = [i] { return i + 1; };
 172     auto explicit_by_value_unused = [i] {}; // expected-warning{{lambda capture 'i' is not used}}
 173   };
 174
 175   Trivial trivial;
 176   auto explicit_by_value_trivial = [trivial] {}; // expected-warning{{lambda capture 'trivial' is not used}}
 177
 178   NonTrivialConstructor cons;
 179   auto explicit_by_value_non_trivial_constructor = [cons] {}; // expected-warning{{lambda capture 'cons' is not used}}
 180
 181   NonTrivialCopyConstructor copy_cons;
 182   auto explicit_by_value_non_trivial_copy_constructor = [copy_cons] {};
 183
 184   NonTrivialDestructor dest;
 185   auto explicit_by_value_non_trivial_destructor = [dest] {};
 186
 187   volatile int v;
 188   auto explicit_by_value_volatile = [v] {};
 189 }
 190
 191 void test_use_template() {
 192   test_templated<int>(); // expected-note{{in instantiation of function template specialization 'test_templated<int>' requested here}}
 193 }
 194
 195 namespace pr35555 {
 196 int a;
 197 void b() {
 198   int c[a];
 199   auto vla_used = [&c] { return c[0]; };
 200   auto vla_unused = [&c] {}; // expected-warning{{lambda capture 'c' is not used}}
 201 }
 202 } // namespace pr35555