gnu/dist/gcc4/gcc/testsuite/gcc.dg/noncompile/label-1.c

   1 /* Test various diagnostics of ill-formed constructs involving labels.  */
   2 /* { dg-do compile } */
   3 /* { dg-options "-Wunused" } */
   4
   5 extern void dummy(void);
   6
   7 /* labels must be defined */
   8 void a(void)
   9 {
  10   goto l;   /* { dg-error "used but not defined" "no label" } */
  11 }
  12
  13 /* warnings for labels defined but not used, or declared but not defined */
  14 void b(void)
  15 {
  16   __label__ l;
  17  l:  /* { dg-warning "defined but not used"  "no goto 1" } */
  18  m:  /* { dg-warning "defined but not used"  "no goto 2" } */
  19   dummy();
  20 }
  21
  22 void c(void)
  23 {
  24   __label__ l;  /* { dg-warning "declared but not defined" "only __label__" } */
  25   dummy();
  26 }
  27
  28 /* can't have two labels with the same name in the same function */
  29 void d(void)
  30 {
  31  l: dummy();  /* { dg-error "previous definition" "prev def same scope" } */
  32  l: dummy();  /* { dg-error "duplicate label" "dup label same scope" } */
  33  goto l;
  34 }
  35
  36 /* even at different scopes */
  37 void e(void)
  38 {
  39  l: dummy();    /* { dg-error "previous definition"  "prev def diff scope" } */
  40   {
  41   l: dummy();   /* { dg-error "duplicate label" "dup label diff scope" } */
  42   }
  43   goto l;
  44 }
  45
  46 /* but, with __label__, you can */
  47 void f(void)
  48 {
  49  l: dummy();
  50   {
  51     __label__ l;
  52     l: dummy();   /* { dg-warning "defined but not used" "unused shadow 1" } */
  53   };
  54   goto l;  /* this reaches the outer l */
  55 }
  56
  57 /* a __label__ is not visible outside its scope */
  58 void g(void)
  59 {
  60   dummy();
  61   {
  62     __label__ l;
  63     l: dummy();
  64     goto l;
  65   }
  66   goto l;  /* { dg-error "used but not defined" "label ref out of scope" } */
  67 }
  68
  69 /* __label__ can appear at top level of a function, too...
  70    ... but doesn't provide a definition of the label */
  71 void h(void)
  72 {
  73   __label__ l;
  74   dummy ();
  75
  76   goto l;  /* { dg-error "used but not defined" "used, only __label__" } */
  77 }
  78
  79 /* A nested function may not goto a label outside itself  */
  80 void i(void)
  81 {
  82   auto void nest(void);
  83
  84  l: nest();
  85
  86   void nest(void)
  87     {
  88       goto l;  /* { dg-error "used but not defined" "nest use outer label" } */
  89     }
  90
  91   goto l; /* reaches the outer l */
  92 }
  93
  94 /* which means that a nested function may have its own label with the
  95    same name as the outer function */
  96 void j(void)
  97 {
  98   auto void nest(void);
  99
 100  l: nest();
 101
 102   void nest(void)
 103     {
 104     l: dummy(); /* { dg-warning "defined but not used" "nest label same name" } */
 105     }
 106
 107   goto l; /* reaches the outer l */
 108 }
 109
 110 /* and, turnabout, an outer function may not goto a label in a nested
 111    function */
 112 void k(void)
 113 {
 114   void nest(void)
 115   {
 116   l: dummy();  /* { dg-warning "defined but not used" "outer use nest label" } */
 117   }
 118
 119   goto l; /* { dg-error "used but not defined" "outer use nest label" } */
 120   nest();
 121 }
 122
 123 /* not even with __label__ */
 124 void l(void)
 125 {
 126   void nest(void)
 127   {
 128     __label__ l;
 129   l: dummy(); /* { dg-warning "defined but not used" "outer use nest __label__" } */
 130   }
 131
 132   goto l; /* { dg-error "used but not defined" "outer use nest __label__" } */
 133   nest();
 134 }
 135
 136
 137 /* but if the outer label is declared with __label__, then a nested
 138    function can goto that label (accomplishing a longjmp) */
 139 void m(void)
 140 {
 141   __label__ l;
 142   void nest(void) { goto l; }
 143   nest();
 144   dummy();
 145  l:;
 146 }
 147
 148 /* and that means the nested function cannot have its own label with
 149    the same name as an outer label declared with __label__ */
 150
 151 void n(void)
 152 {
 153   __label__ l; /* { dg-error "previous declaration" "outer label decl" } */
 154   void nest(void)
 155     {
 156     l: goto l;  /* { dg-error "duplicate label" "inner label defn" } */
 157     }
 158
 159  l:
 160   nest();
 161 }
 162
 163 /* unless the nested function uses __label__ too!  */
 164 void o(void)
 165 {
 166   __label__ l;
 167   void nest(void)
 168     {
 169       __label__ l;
 170     l: goto l;
 171     }
 172
 173  l: goto l;
 174  nest();
 175 }