switch-implicit-fallthrough.cpp revision 878d0ad2c9d83ee6485fd16e21c5082acc63a890 
1// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wimplicit-fallthrough %s
2
3
4int fallthrough(int n) {
5  switch (n / 10) {
6      if (n - 1) {
7        n = 100;
8      } else if (n - 2) {
9        n = 101;
10      } else if (n - 3) {
11        n = 102;
12      }
13    case -1:  // no warning here, ignore fall-through from unreachable code
14      ;
15    case 0: {// expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
16    }
17    case 1:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
18      n += 100         ;
19    case 3:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
20      if (n > 0)
21        n += 200;
22    case 4:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
23      if (n < 0)
24        ;
25    case 5:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
26      switch (n) {
27      case 111:
28        break;
29      case 112:
30        break;
31      case 113:
32        break    ;
33      }
34    case 6:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
35      n += 300;
36    case 66:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert 'break;' to avoid fall-through}}
37    case 67:
38    case 68:
39      break;
40  }
41  switch (n / 15) {
42label_default:
43    default:
44      n += 333;
45      if (n % 10)
46        goto label_default;
47      break;
48    case 70:
49      n += 335;
50      break;
51  }
52  switch (n / 20) {
53    case 7:
54      n += 400;
55      [[clang::fallthrough]];
56    case 9:  // no warning here, intended fall-through marked with an attribute
57      n += 800;
58      [[clang::fallthrough]];
59    default: { // no warning here, intended fall-through marked with an attribute
60      if (n % 2 == 0) {
61        return 1;
62      } else {
63        [[clang::fallthrough]];
64      }
65    }
66    case 10:  // no warning here, intended fall-through marked with an attribute
67      if (n % 3 == 0) {
68        n %= 3;
69      } else {
70        [[clang::fallthrough]];
71      }
72    case 110:  // expected-warning{{unannotated fall-through between switch labels}} but no fix-it hint as we have one fall-through annotation!
73      n += 800;
74  }
75  switch (n / 30) {
76    case 11:
77    case 12:  // no warning here, intended fall-through, no statement between labels
78      n += 1600;
79  }
80  switch (n / 40) {
81    case 13:
82      if (n % 2 == 0) {
83        return 1;
84      } else {
85        return 2;
86      }
87    case 15:  // no warning here, there's no fall-through
88      n += 3200;
89  }
90  switch (n / 50) {
91    case 17: {
92      if (n % 2 == 0) {
93        return 1;
94      } else {
95        return 2;
96      }
97    }
98    case 19: { // no warning here, there's no fall-through
99      n += 6400;
100      return 3;
101    }
102    case 21: { // no warning here, there's no fall-through
103      break;
104    }
105    case 23: // no warning here, there's no fall-through
106      n += 128000;
107      break;
108    case 25: // no warning here, there's no fall-through
109      break;
110  }
111
112  return n;
113}
114
115class ClassWithDtor {
116public:
117  ~ClassWithDtor() {}
118};
119
120void fallthrough2(int n) {
121  switch (n) {
122    case 0:
123    {
124      ClassWithDtor temp;
125      break;
126    }
127    default: // no warning here, there's no fall-through
128      break;
129  }
130}
131
132void fallthrough3(int n) {
133  switch (n) {
134    case 1:
135      do {
136        return;
137      } while (0);
138    case 2:
139      do {
140        ClassWithDtor temp;
141        return;
142      } while (0);
143    case 3:
144      break;
145  }
146}
147
148#define MY_SWITCH(X, Y, Z, U, V) switch (X) { case Y: Z; case U: V; }
149#define MY_SWITCH2(X, Y, Z) switch (X) { Y; Z; }
150#define MY_CASE(X, Y) case X: Y
151#define MY_CASE2(X, Y, U, V) case X: Y; case U: V
152
153int fallthrough_macro1(int n) {
154  MY_SWITCH(n, 13, n *= 2, 14, break)  // expected-warning{{unannotated fall-through between switch labels}}
155
156  switch (n + 1) {
157    MY_CASE(33, n += 2);
158    MY_CASE(44, break);  // expected-warning{{unannotated fall-through between switch labels}}
159    MY_CASE(55, n += 3);
160  }
161
162  switch (n + 3) {
163    MY_CASE(333, return 333);
164    MY_CASE2(444, n += 44, 4444, break);  // expected-warning{{unannotated fall-through between switch labels}}
165    MY_CASE(555, n += 33);
166  }
167
168  MY_SWITCH2(n + 4, MY_CASE(17, n *= 3), MY_CASE(19, break))  // expected-warning{{unannotated fall-through between switch labels}}
169
170  MY_SWITCH2(n + 5, MY_CASE(21, break), MY_CASE2(23, n *= 7, 25, break))  // expected-warning{{unannotated fall-through between switch labels}}
171
172  return n;
173}
174
175void fallthrough_cfgblock_with_null_successor(int x) {
176  (x && "") ? (void)(0) : (void)(1);
177  switch (x) {}
178}
179
180int fallthrough_position(int n) {
181  switch (n) {
182      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation does not directly precede switch label}}
183      n += 300;
184      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation in unreachable code}}
185    case 221:
186      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation does not directly precede switch label}}
187      return 1;
188      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation in unreachable code}}
189    case 222:
190      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation does not directly precede switch label}}
191      n += 400;
192    case 223:          // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
193      [[clang::fallthrough]]; // expected-warning{{fallthrough annotation does not directly precede switch label}}
194  }
195
196  long p = static_cast<long>(n) * n;
197  switch (sizeof(p)) {
198    case 9:
199      n += static_cast<int>(p >> 32);
200      [[clang::fallthrough]];  // no warning here
201    case 5:
202      n += static_cast<int>(p);
203      [[clang::fallthrough]];  // no warning here
204    default:
205      n += 1;
206      break;
207  }
208
209  return n;
210}
211
212enum Enum {
213  Value1, Value2
214};
215
216int fallthrough_covered_enums(Enum e) {
217  int n = 0;
218  switch (e) {
219    default:
220      n += 17;
221      [[clang::fallthrough]];  // no warning here, this shouldn't be treated as unreachable code
222    case Value1:
223      n += 19;
224      break;
225    case Value2:
226      n += 21;
227      break;
228  }
229  return n;
230}
231
232int fallthrough_targets(int n) {
233  [[clang::fallthrough]]; // expected-error{{fallthrough annotation is outside switch statement}}
234
235  [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
236  switch (n) {
237    case 121:
238      n += 400;
239      [[clang::fallthrough]]; // no warning here, correct target
240    case 123:
241      [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
242      n += 800;
243      break;
244    [[clang::fallthrough]]    // expected-error{{fallthrough attribute is only allowed on empty statements}} expected-note{{did you forget ';'?}}
245    case 125:
246      n += 1600;
247  }
248  return n;
249}
250