clang/test/SemaCXX/warn-empty-body.cpp

   1 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
   2
   3 void a(int i);
   4 int b();
   5 int c();
   6
   7 #define MACRO_A 0
   8
   9 void test1(int x, int y) {
  10   while(true) {
  11     if (x); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  12
  13     // Check that we handle conditions that start or end with a macro
  14     // correctly.
  15     if (x == MACRO_A); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  16     if (MACRO_A == x); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  17
  18     int i;
  19     // PR11329
  20     for (i = 0; i < x; i++); { // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  21       a(i);
  22       b();
  23     }
  24
  25     for (i = 0; i < x; i++); // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  26     {
  27       a(i);
  28     }
  29
  30     for (i = 0;
  31          i < x;
  32          i++); // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  33     {
  34       a(i);
  35     }
  36
  37     int arr[3] = { 1, 2, 3 };
  38     for (int j : arr); // expected-warning{{range-based for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  39       a(i);
  40
  41     for (int j :
  42          arr); // expected-warning{{range-based for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  43       a(i);
  44
  45     while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  46       a(i);
  47
  48     while (b() == 0); { // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  49       a(i);
  50     }
  51
  52     while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  53     {
  54       a(i);
  55     }
  56
  57     while (b() == 0 ||
  58            c() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  59     {
  60       a(i);
  61     }
  62
  63     do;          // expected-note{{to match this 'do'}}
  64       b();       // expected-error{{expected 'while' in do/while loop}}
  65     while (b()); // no-warning
  66     c();
  67
  68     do;          // expected-note{{to match this 'do'}}
  69       b();       // expected-error{{expected 'while' in do/while loop}}
  70     while (b()); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  71       c();
  72
  73     switch(x) // no-warning
  74     {
  75       switch(y); // expected-warning{{switch statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  76       {
  77         case 0:
  78           a(10);
  79           break;
  80         default:
  81           a(20);
  82           break;
  83       }
  84     }
  85   }
  86 }
  87
  88 /// There should be no warning  when null statement is placed on its own line.
  89 void test2(int x, int y) {
  90   if (x) // no-warning
  91     ; // no-warning
  92
  93   int i;
  94   for (i = 0; i < x; i++) // no-warning
  95     ; // no-warning
  96
  97   for (i = 0;
  98        i < x;
  99        i++) // no-warning
 100     ; // no-warning
 101
 102   int arr[3] = { 1, 2, 3 };
 103   for (int j : arr) // no-warning
 104     ; // no-warning
 105
 106   while (b() == 0) // no-warning
 107     ; // no-warning
 108
 109   while (b() == 0 ||
 110          c() == 0) // no-warning
 111     ; // no-warning
 112
 113   switch(x)
 114   {
 115     switch(y) // no-warning
 116       ; // no-warning
 117   }
 118
 119   // Last `for' or `while' statement in compound statement shouldn't warn.
 120   while(b() == 0); // no-warning
 121 }
 122
 123 /// There should be no warning for a null statement resulting from an empty macro.
 124 #define EMPTY(a)
 125 void test3(int x, int y) {
 126   if (x) EMPTY(x); // no-warning
 127
 128   int i;
 129   for (i = 0; i < x; i++) EMPTY(i); // no-warning
 130
 131   for (i = 0;
 132        i < x;
 133        i++) EMPTY(i); // no-warning
 134
 135   int arr[3] = { 1, 2, 3 };
 136   for (int j : arr) EMPTY(j); // no-warning
 137
 138   for (int j :
 139        arr) EMPTY(j); // no-warning
 140
 141   while (b() == 0) EMPTY(i); // no-warning
 142
 143   while (b() == 0 ||
 144          c() == 0) EMPTY(i); // no-warning
 145
 146   switch (x) {
 147     switch (y)
 148       EMPTY(i); // no-warning
 149   }
 150 }
 151
 152 void test4(int x)
 153 {
 154   // Idiom used in some metaprogramming constructs.
 155   switch (x) default:; // no-warning
 156
 157   // Frequent idiom used in macros.
 158   do {} while (false); // no-warning
 159 }
 160
 161 /// There should be no warning for a common for/while idiom when it is obvious
 162 /// from indentation that next statement wasn't meant to be a body.
 163 void test5(int x, int y) {
 164   int i;
 165   for (i = 0; i < x; i++); // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 166     a(i);
 167
 168   for (i = 0; i < x; i++); // no-warning
 169   a(i);
 170
 171   for (i = 0;
 172        i < x;
 173        i++); // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 174     a(i);
 175
 176   for (i = 0;
 177        i < x;
 178        i++); // no-warning
 179   a(i);
 180
 181   while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 182     a(i);
 183
 184   while (b() == 0); // no-warning
 185   a(i);
 186
 187   while (b() == 0 ||
 188          c() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 189     a(i);
 190
 191   while (b() == 0 ||
 192          c() == 0); // no-warning
 193   a(i);
 194 }
 195
 196 /// There should be no warning for a statement with a non-null body.
 197 void test6(int x, int y) {
 198   if (x) {} // no-warning
 199
 200   if (x)
 201     a(x); // no-warning
 202
 203   int i;
 204   for (i = 0; i < x; i++) // no-warning
 205     a(i); // no-warning
 206
 207   for (i = 0; i < x; i++) { // no-warning
 208     a(i); // no-warning
 209   }
 210
 211   for (i = 0;
 212        i < x;
 213        i++) // no-warning
 214     a(i); // no-warning
 215
 216   int arr[3] = { 1, 2, 3 };
 217   for (int j : arr) // no-warning
 218     a(j);
 219
 220   for (int j : arr) {} // no-warning
 221
 222   while (b() == 0) // no-warning
 223     a(i); // no-warning
 224
 225   while (b() == 0) {} // no-warning
 226
 227   switch(x) // no-warning
 228   {
 229     switch(y) // no-warning
 230     {
 231       case 0:
 232         a(10);
 233         break;
 234       default:
 235         a(20);
 236         break;
 237     }
 238   }
 239 }
 240
 241 void test_errors(int x) {
 242   if (1)
 243     aa; // expected-error{{use of undeclared identifier}}
 244         // no empty body warning.
 245
 246   int i;
 247   for (i = 0; i < x; i++)
 248     bb; // expected-error{{use of undeclared identifier}}
 249
 250   int arr[3] = { 1, 2, 3 };
 251   for (int j : arr)
 252     cc; // expected-error{{use of undeclared identifier}}
 253
 254   while (b() == 0)
 255     dd; // expected-error{{use of undeclared identifier}}
 256 }
 257
 258 // Warnings for statements in templates shouldn't be duplicated for all
 259 // instantiations.
 260 template <typename T>
 261 void test_template(int x) {
 262   if (x); // expected-warning{{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 263
 264   if (x)
 265     EMPTY(x); // no-warning
 266
 267   int arr[3] = { 1, 2, 3 };
 268   for (int j : arr); // expected-warning{{range-based for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 269
 270   while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 271     a(x);
 272 }
 273
 274 void test_template_inst(int x) {
 275   test_template<int>(x);
 276   test_template<double>(x);
 277 }
 278
 279 #define IDENTITY(a) a
 280 void test7(int x, int y) {
 281   if (x) IDENTITY(); // no-warning
 282 }
 283