gdb/testsuite/gdb.cp/oranking.cc

   1
   2 /* 1. A standard covnersion sequence is better than a user-defined sequence
   3       which is better than an elipses conversion sequence.  */
   4
   5 class A{};
   6 class B: public A {public: operator int (){ return 1;}};
   7
   8 // standard vs user-defined
   9 int foo0  (int) { return 10; }
  10 int foo1  (int) { return 11; } // B -> int   : user defined
  11 int foo1  (A)   { return 12; } // B -> A     : standard
  12 int test1 () {
  13   B b;
  14   return foo1(b); // 12
  15 }
  16
  17 // user-defined vs ellipsis
  18 int foo2 (int) { return 13;} // B -> int   : user defined
  19 int foo2 (...) { return 14;} // B -> ...   : ellipsis
  20 int test2(){
  21   B b;
  22   return foo2(b); // 13
  23 }
  24
  25 /* 2. Standard Conversion squence S1 is better than standard Conversion
  26       S2 if:  */
  27
  28 //      - S1 has a better rank than S2
  29 //        see overload.exp for more comprehensive testing of this.
  30 int foo3 (double) { return 21; } // float->double is 'promotion rank'
  31 int foo3 (int)    { return 22; } // float->int is 'conversion rank'
  32 int test3(){
  33   return foo3 (1.0f); // 21
  34 }
  35
  36 //      - S1 and S2 are both 'qualification conversions' but S1 cv-qualification
  37 //        is a subset of S2 cv-qualification.
  38 int foo4 (const volatile int*) { return 23; }
  39 int foo4 (      volatile int*) { return 24; }
  40 int test4 () {
  41   volatile int a = 5;
  42   return foo4(&a); // 24
  43 }
  44
  45 //      - S1 and S2 have the same rank but:
  46 //        - S2 is a conversion of pointer or memeber-pointer to bool
  47 int foo5 (bool)  { return 25; }
  48 int foo5 (void*) { return 26; }
  49 int test5 () {
  50   char *a;
  51   return foo5(a); // 26
  52 }
  53
  54 //        - Class B publicly extends class A and S1 is a conversion of
  55 //          B* to A* and S2 is a conversion B* to void*
  56 int foo6 (void*) { return 27; }
  57 int foo6 (A*)    { return 28; }
  58 int test6 () {
  59   B *bp;
  60   return foo6(bp); // 28
  61 }
  62
  63 //        - Class C publicly extends Class B which publicly extends
  64 //          class A and S1 is a conversion of C* to B* and S2 is a
  65 //          conversion C* to A*.
  66 class C: public B {};
  67 int foo7 (A*)    { return 29; }
  68 int foo7 (B*) { return 210; }
  69 int test7 () {
  70   C *cp;
  71   return foo7(cp); // 210
  72 }
  73
  74 //        - Same as above but for references.
  75 int foo8 (A&) { return 211; }
  76 int foo8 (B&) { return 212; }
  77 int test8 () {
  78   C c;
  79   return foo8(c); // 212
  80 }
  81
  82 //        - Same as above but passing by copy.
  83 int foo9 (A) { return 213; }
  84 int foo9 (B) { return 214; }
  85 int test9 () {
  86   C c;
  87   return foo9(c); // 212
  88 }
  89
  90 //        - S1 is a conversion of A::* to B::* and S2 is a conversion of
  91 //          A::* to C::8.
  92 int foo10 (void (C::*)()) { return 215; }
  93 int foo10 (void (B::*)()) { return 216; }
  94 int test10 () {
  95   void (A::*amp)();
  96   return foo10(amp); // 216
  97 }
  98
  99 //      - S1 is a subsequence of S2
 100 int foo101 (volatile const char*) { return 217; } // array-to-pointer conversion
 101                                                  // plus qualification conversion
 102 int foo101 (         const char*) { return 218; } // array-to-pointer conversion
 103
 104 int test101 () {
 105   return foo101("abc"); // 216
 106 }
 107
 108 /* 3. User defined conversion U1 is better than user defined Conversion U2,
 109       if U1 and U2 are using the same conversion function but U1 has a better
 110       second standard conversion sequence than U2.  */
 111 class D {public: operator short(){ return 0;}};
 112 int foo11 (float) { return 31; }
 113 int foo11 (int)   { return 32; }
 114 int test11 () {
 115   D d;
 116   return foo11(d); // 32
 117 }
 118
 119 /* 4. Function Level Ranking.
 120       All else being equal some functions are preferred by overload resolution.
 121       Function F1 is better than function F2 if: */
 122 //    - F1 is a non-template function and F2 is a template function
 123 template<class T> int foo12(T)   { return 41; }
 124                   int foo12(int) { return 42; }
 125 int test12 (){
 126   return foo12(1); //42
 127 }
 128
 129 //    - F1 is a more specialized template instance
 130 template<class T> int foo13(T)  { return 43; }
 131 template<class T> int foo13(T*) { return 44; }
 132 int test13 (){
 133   char *c;
 134   return foo13(c); // 44
 135 }
 136
 137 //    - The context is user defined conversion and F1 has
 138 //      a better return type than F2
 139 class E {
 140   public:
 141     operator double () {return 45; }
 142     operator int    () {return 46; }
 143 };
 144 int foo14 (int a) {return a;}
 145 int test14 (){
 146   E e;
 147   return foo14(e); // 46
 148 }
 149
 150 int main() {
 151   B b;
 152   foo0(b);
 153   foo1(b);
 154   test1();
 155
 156   foo2(b);
 157   test2();
 158
 159   foo3(1.0f);
 160   test3();
 161
 162   volatile int a;
 163   foo4(&a);
 164   test4();
 165
 166   char *c;
 167   foo5(c);
 168   test5();
 169
 170   B *bp;
 171   foo6(bp);
 172   test6();
 173
 174   C *cp;
 175   foo7(cp);
 176   test7();
 177
 178   C co;
 179   foo8(co);
 180   test8();
 181
 182   foo9(co);
 183   test9();
 184
 185   void (A::*amp)();
 186   foo10(amp);
 187   test10();
 188
 189   foo101("abc");
 190   test101();
 191
 192   D d;
 193   foo11(d);
 194   test11();
 195
 196   foo12(1);
 197   test12();
 198
 199   foo13(c);
 200   test13();
 201
 202   E e;
 203   foo14(e);
 204   test14();
 205
 206   return 0; // end of main
 207 }