clang/test/SemaCXX/warn-shadow-in-lambdas.cpp

   1 // RUN: %clang_cc1 -std=c++14 -verify -fsyntax-only -Wshadow -D AVOID %s
   2 // RUN: %clang_cc1 -std=c++14 -verify -fsyntax-only -Wshadow -Wshadow-uncaptured-local %s
   3 // RUN: %clang_cc1 -std=c++14 -verify -fsyntax-only -Wshadow-all %s
   4 // RUN: %clang_cc1 -std=c++17 -verify -fsyntax-only -Wshadow-all %s
   5
   6 void foo(int param) { // expected-note 1+ {{previous declaration is here}}
   7   int var = 0; // expected-note 1+ {{previous declaration is here}}
   8
   9   // Avoid warnings for variables that aren't implicitly captured.
  10   {
  11 #ifdef AVOID
  12     auto f1 = [=] { int var = 1; };  // no warning
  13     auto f2 = [&] { int var = 2; };  // no warning
  14     auto f3 = [=] (int param) { ; }; // no warning
  15     auto f4 = [&] (int param) { ; }; // no warning
  16 #else
  17     auto f1 = [=] { int var = 1; };  // expected-warning {{declaration shadows a local variable}}
  18     auto f2 = [&] { int var = 2; };  // expected-warning {{declaration shadows a local variable}}
  19     auto f3 = [=] (int param) { ; }; // expected-warning {{declaration shadows a local variable}}
  20     auto f4 = [&] (int param) { ; }; // expected-warning {{declaration shadows a local variable}}
  21 #endif
  22   }
  23
  24   // Warn for variables that are implicitly captured.
  25   {
  26     auto f1 = [=] () {
  27       {
  28         int var = 1; // expected-warning {{declaration shadows a local variable}}
  29       }
  30       int x = var; // expected-note {{variable 'var' is captured here}}
  31     };
  32     auto f2 = [&]
  33 #ifdef AVOID
  34       (int param) {
  35 #else
  36       (int param) { // expected-warning {{declaration shadows a local variable}}
  37 #endif
  38       int x = var; // expected-note {{variable 'var' is captured here}}
  39       int var = param; // expected-warning {{declaration shadows a local variable}}
  40     };
  41   }
  42
  43   // Warn for variables that are explicitly captured when a lambda has a default
  44   // capture specifier.
  45   {
  46     auto f1 = [=, &var] () { // expected-note {{variable 'var' is captured here}}
  47       int x = param; // expected-note {{variable 'param' is captured here}}
  48       int var = 0; // expected-warning {{declaration shadows a local variable}}
  49       int param = 0; // expected-warning {{declaration shadows a local variable}}
  50     };
  51   }
  52
  53   // Warn normally inside of lambdas.
  54   auto l1 = [] { // expected-note {{previous declaration is here}}
  55       int x = 1; // expected-note {{previous declaration is here}}
  56       { int x = 2; } // expected-warning {{declaration shadows a local variable}}
  57   };
  58   auto l2 = [] (int x) { // expected-note {{previous declaration is here}}
  59     { int x = 1; } // expected-warning {{declaration shadows a local variable}}
  60   };
  61
  62   // Avoid warnings for variables that aren't explicitly captured.
  63   {
  64 #ifdef AVOID
  65     auto f1 = [] { int var = 1; }; // no warning
  66     auto f2 = [] (int param) { ; }; // no warning
  67     auto f3 = [param] () { int var = 1; }; // no warning
  68     auto f4 = [var] (int param) { ; }; // no warning
  69 #else
  70     auto f1 = [] { int var = 1; }; // expected-warning {{declaration shadows a local variable}}
  71     auto f2 = [] (int param) { ; }; // expected-warning {{declaration shadows a local variable}}
  72     auto f3 = [param] () { int var = 1; }; // expected-warning {{declaration shadows a local variable}}
  73     auto f4 = [var] (int param) { ; }; // expected-warning {{declaration shadows a local variable}}
  74 #endif
  75   };
  76
  77   // Warn for variables that are explicitly captured.
  78   {
  79     auto f1 = [var] () { // expected-note {{variable 'var' is explicitly captured here}}
  80       int var = 1; // expected-warning {{declaration shadows a local variable}}
  81     };
  82     auto f2 = [param]   // expected-note {{variable 'param' is explicitly captured here}}
  83      (int param) { ; }; // expected-error {{a lambda parameter cannot shadow an explicitly captured entity}}
  84   }
  85
  86   // Warn for variables defined in the capture list.
  87   auto l3 = [z = var] { // expected-note {{previous declaration is here}}
  88 #ifdef AVOID
  89     int var = 1; // no warning
  90 #else
  91     int var = 1; // expected-warning {{declaration shadows a local variable}}
  92 #endif
  93     { int z = 1; } // expected-warning {{declaration shadows a local variable}}
  94   };
  95 #ifdef AVOID
  96   auto l4 = [var = param] (int param) { ; }; // no warning
  97 #else
  98   auto l4 = [var = param] (int param) { ; }; // expected-warning {{declaration shadows a local variable}}
  99 #endif
 100
 101   // Make sure that inner lambdas work as well.
 102   auto l5 = [var, l1] { // expected-note {{variable 'l1' is explicitly captured here}}
 103     auto l1 = [] { // expected-warning {{declaration shadows a local variable}}
 104 #ifdef AVOID
 105       int var = 1; // no warning
 106 #else
 107       int var = 1; // expected-warning {{declaration shadows a local variable}}
 108 #endif
 109     };
 110 #ifdef AVOID
 111     auto f1 = [] { int var = 1; }; // no warning
 112     auto f2 = [=] { int var = 1; }; // no warning
 113 #else
 114     auto f1 = [] { int var = 1; }; // expected-warning {{declaration shadows a local variable}}
 115     auto f2 = [=] { int var = 1; }; // expected-warning {{declaration shadows a local variable}}
 116 #endif
 117     auto f3 = [var] // expected-note {{variable 'var' is explicitly captured here}}
 118       { int var = 1; }; // expected-warning {{declaration shadows a local variable}}
 119     auto f4 = [&] {
 120       int x = var; // expected-note {{variable 'var' is captured here}}
 121       int var = 2; // expected-warning {{declaration shadows a local variable}}
 122     };
 123   };
 124   auto l6 = [&] {
 125     auto f1 = [param] { // expected-note {{variable 'param' is explicitly captured here}}
 126       int param = 0; // expected-warning {{declaration shadows a local variable}}
 127     };
 128   };
 129
 130   // Generic lambda arguments should work.
 131 #ifdef AVOID
 132   auto g1 = [](auto param) { ; }; // no warning
 133   auto g2 = [=](auto param) { ; }; // no warning
 134 #else
 135   auto g1 = [](auto param) { ; }; // expected-warning {{declaration shadows a local variable}}
 136   auto g2 = [=](auto param) { ; }; // expected-warning {{declaration shadows a local variable}}
 137 #endif
 138   auto g3 = [param] // expected-note {{variable 'param' is explicitly captured here}}
 139    (auto param) { ; }; // expected-error {{a lambda parameter cannot shadow an explicitly captured entity}}
 140 }
 141
 142 void avoidWarningWhenRedefining() {
 143   int a = 1;
 144   auto l = [b = a] { // expected-note {{previous definition is here}}
 145     // Don't warn on redefinitions.
 146     int b = 0; // expected-error {{redefinition of 'b'}}
 147   };
 148 }