switch-implicit-fallthrough.cpp revision 4874a8143dc3032205f97527ff619730db3d1f57 
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
175int fallthrough_position(int n) {
176  switch (n) {
177      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation in unreachable code}}
178    case 221:
179      [[clang::fallthrough]]; // expected-warning{{fallthrough annotation does not directly precede switch label}}
180      return 1;
181      [[clang::fallthrough]];  // expected-warning{{fallthrough annotation in unreachable code}}
182    case 222:
183      [[clang::fallthrough]]; // expected-warning{{fallthrough annotation does not directly precede switch label}}
184      n += 400;
185    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}}
186      [[clang::fallthrough]]; // expected-warning{{fallthrough annotation does not directly precede switch label}}
187  }
188
189  // TODO: uncomment this test after CFG gets more options to deal with
190  // unreachable code:
191  // http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20120507/057370.html
192#if 0
193  long p = static_cast<long>(n) * n;
194  switch (sizeof(p)) {
195    case 9:                    // this test will not work on compilers with 72-bit long
196      n += static_cast<int>(p >> 32);
197      [[clang::fallthrough]];  // no warning here
198    case 5:                    // it is not intended to work on compilers with 40-bit long as well
199      n += static_cast<int>(p);
200      break;
201    default:
202     break;
203  }
204#endif
205
206  return n;
207}
208
209int fallthrough_targets(int n) {
210  [[clang::fallthrough]]; // expected-error{{fallthrough annotation is outside switch statement}}
211
212  [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
213  switch (n) {
214    case 121:
215      n += 400;
216      [[clang::fallthrough]]; // no warning here, correct target
217    case 123:
218      [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
219      n += 800;
220      break;
221    [[clang::fallthrough]]    // expected-error{{fallthrough attribute is only allowed on empty statements}} expected-note{{did you forget ';'?}}
222    case 125:
223      n += 1600;
224  }
225  return n;
226}
227