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 #define AND(x, y) ((x) && (y))
  10
  11 void test1(int x, int y) {
  12   while(true) {
  13     if (x); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  14
  15     // Check that we handle conditions that start or end with a macro
  16     // correctly.
  17     if (x == MACRO_A); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  18     if (MACRO_A == x); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  19
  20     // Check that we handle the case where the condition comes from a macro
  21     // expansion over multiple lines.
  22     if (AND(b(),
  23             c())); // expected-warning {{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  24
  25     while (AND(b(),
  26                c())); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  27       a(0);
  28
  29     int i;
  30     // PR11329
  31     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}}
  32       a(i);
  33       b();
  34     }
  35
  36     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}}
  37     {
  38       a(i);
  39     }
  40
  41     for (i = 0;
  42          i < x;
  43          i++); // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  44     {
  45       a(i);
  46     }
  47
  48     int arr[3] = { 1, 2, 3 };
  49     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}}
  50       a(i);
  51
  52     for (int j :
  53          arr); // expected-warning{{range-based for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  54       a(i);
  55
  56     while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  57       a(i);
  58
  59     while (b() == 0); { // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  60       a(i);
  61     }
  62
  63     while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  64     {
  65       a(i);
  66     }
  67
  68     while (b() == 0 ||
  69            c() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  70     {
  71       a(i);
  72     }
  73
  74     do;          // expected-note{{to match this 'do'}}
  75       b();       // expected-error{{expected 'while' in do/while loop}}
  76     while (b()); // no-warning
  77     c();
  78
  79     do;          // expected-note{{to match this 'do'}}
  80       b();       // expected-error{{expected 'while' in do/while loop}}
  81     while (b()); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  82       c();
  83
  84     switch(x) // no-warning
  85     {
  86       switch(y); // expected-warning{{switch statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
  87       {
  88         case 0:
  89           a(10);
  90           break;
  91         default:
  92           a(20);
  93           break;
  94       }
  95     }
  96   }
  97 }
  98
  99 /// There should be no warning  when null statement is placed on its own line.
 100 void test2(int x, int y) {
 101   if (x) // no-warning
 102     ; // no-warning
 103
 104   int i;
 105   for (i = 0; i < x; i++) // no-warning
 106     ; // no-warning
 107
 108   for (i = 0;
 109        i < x;
 110        i++) // no-warning
 111     ; // no-warning
 112
 113   int arr[3] = { 1, 2, 3 };
 114   for (int j : arr) // no-warning
 115     ; // no-warning
 116
 117   while (b() == 0) // no-warning
 118     ; // no-warning
 119
 120   while (b() == 0 ||
 121          c() == 0) // no-warning
 122     ; // no-warning
 123
 124   switch(x)
 125   {
 126     switch(y) // no-warning
 127       ; // no-warning
 128   }
 129
 130   // Last `for' or `while' statement in compound statement shouldn't warn.
 131   while(b() == 0); // no-warning
 132 }
 133
 134 /// There should be no warning for a null statement resulting from an empty macro.
 135 #define EMPTY(a)
 136 void test3(int x, int y) {
 137   if (x) EMPTY(x); // no-warning
 138
 139   int i;
 140   for (i = 0; i < x; i++) EMPTY(i); // no-warning
 141
 142   for (i = 0;
 143        i < x;
 144        i++) EMPTY(i); // no-warning
 145
 146   int arr[3] = { 1, 2, 3 };
 147   for (int j : arr) EMPTY(j); // no-warning
 148
 149   for (int j :
 150        arr) EMPTY(j); // no-warning
 151
 152   while (b() == 0) EMPTY(i); // no-warning
 153
 154   while (b() == 0 ||
 155          c() == 0) EMPTY(i); // no-warning
 156
 157   switch (x) {
 158     switch (y)
 159       EMPTY(i); // no-warning
 160   }
 161 }
 162
 163 void test4(int x)
 164 {
 165   // Idiom used in some metaprogramming constructs.
 166   switch (x) default:; // no-warning
 167
 168   // Frequent idiom used in macros.
 169   do {} while (false); // no-warning
 170 }
 171
 172 /// There should be no warning for a common for/while idiom when it is obvious
 173 /// from indentation that next statement wasn't meant to be a body.
 174 void test5(int x, int y) {
 175   int i;
 176   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}}
 177     a(i);
 178
 179   for (i = 0; i < x; i++); // no-warning
 180   a(i);
 181
 182   for (i = 0;
 183        i < x;
 184        i++); // expected-warning{{for loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 185     a(i);
 186
 187   for (i = 0;
 188        i < x;
 189        i++); // no-warning
 190   a(i);
 191
 192   while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 193     a(i);
 194
 195   while (b() == 0); // no-warning
 196   a(i);
 197
 198   while (b() == 0 ||
 199          c() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 200     a(i);
 201
 202   while (b() == 0 ||
 203          c() == 0); // no-warning
 204   a(i);
 205 }
 206
 207 /// There should be no warning for a statement with a non-null body.
 208 void test6(int x, int y) {
 209   if (x) {} // no-warning
 210
 211   if (x)
 212     a(x); // no-warning
 213
 214   int i;
 215   for (i = 0; i < x; i++) // no-warning
 216     a(i); // no-warning
 217
 218   for (i = 0; i < x; i++) { // no-warning
 219     a(i); // no-warning
 220   }
 221
 222   for (i = 0;
 223        i < x;
 224        i++) // no-warning
 225     a(i); // no-warning
 226
 227   int arr[3] = { 1, 2, 3 };
 228   for (int j : arr) // no-warning
 229     a(j);
 230
 231   for (int j : arr) {} // no-warning
 232
 233   while (b() == 0) // no-warning
 234     a(i); // no-warning
 235
 236   while (b() == 0) {} // no-warning
 237
 238   switch(x) // no-warning
 239   {
 240     switch(y) // no-warning
 241     {
 242       case 0:
 243         a(10);
 244         break;
 245       default:
 246         a(20);
 247         break;
 248     }
 249   }
 250 }
 251
 252 void test_errors(int x) {
 253   if (1)
 254     aa; // expected-error{{use of undeclared identifier}}
 255         // no empty body warning.
 256
 257   int i;
 258   for (i = 0; i < x; i++)
 259     bb; // expected-error{{use of undeclared identifier}}
 260
 261   int arr[3] = { 1, 2, 3 };
 262   for (int j : arr)
 263     cc; // expected-error{{use of undeclared identifier}}
 264
 265   while (b() == 0)
 266     dd; // expected-error{{use of undeclared identifier}}
 267 }
 268
 269 // Warnings for statements in templates shouldn't be duplicated for all
 270 // instantiations.
 271 template <typename T>
 272 void test_template(int x) {
 273   if (x); // expected-warning{{if statement has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 274
 275   if (x)
 276     EMPTY(x); // no-warning
 277
 278   int arr[3] = { 1, 2, 3 };
 279   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}}
 280
 281   while (b() == 0); // expected-warning{{while loop has empty body}} expected-note{{put the semicolon on a separate line to silence this warning}}
 282     a(x);
 283 }
 284
 285 void test_template_inst(int x) {
 286   test_template<int>(x);
 287   test_template<double>(x);
 288 }
 289
 290 #define IDENTITY(a) a
 291 void test7(int x, int y) {
 292   if (x) IDENTITY(); // no-warning
 293 }
 294