clang/test/SemaCXX/const-cast.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
   3 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
   4
   5 struct A {};
   6
   7 // See if aliasing can confuse this baby.
   8 typedef char c;
   9 typedef c *cp;
  10 typedef cp *cpp;
  11 typedef cpp *cppp;
  12 typedef cppp &cpppr;
  13 typedef const cppp &cpppcr;
  14 typedef const char cc;
  15 typedef cc *ccp;
  16 typedef volatile ccp ccvp;
  17 typedef ccvp *ccvpp;
  18 typedef const volatile ccvpp ccvpcvp;
  19 typedef ccvpcvp *ccvpcvpp;
  20 typedef int iar[100];
  21 typedef iar &iarr;
  22 typedef int (*f)(int);
  23
  24 char ***good_const_cast_test(ccvpcvpp var)
  25 {
  26   // Cast away deep consts and volatiles.
  27   char ***var2 = const_cast<cppp>(var);
  28   char ***const &var3 = var2;
  29   // Const reference to reference.
  30   char ***&var4 = const_cast<cpppr>(var3);
  31   // Drop reference. Intentionally without qualifier change.
  32   char *** var5 = const_cast<cppp>(var4);
  33   // Const array to array reference.
  34   const int ar[100] = {0};
  35   int (&rar)[100] = const_cast<iarr>(ar);
  36   // Array decay. Intentionally without qualifier change.
  37   int *pi = const_cast<int*>(ar);
  38   f fp = 0;
  39   // Don't misidentify fn** as a function pointer.
  40   f *fpp = const_cast<f*>(&fp);
  41   int const A::* const A::*icapcap = 0;
  42   int A::* A::* iapap = const_cast<int A::* A::*>(icapcap);
  43   (void)const_cast<A&&>(A());
  44 #if __cplusplus <= 199711L // C++03 or earlier modes
  45   // expected-warning@-2 {{rvalue references are a C++11 extension}}
  46 #endif
  47   return var4;
  48 }
  49
  50 short *bad_const_cast_test(char const *volatile *const volatile *var)
  51 {
  52   // Different pointer levels.
  53   char **var2 = const_cast<char**>(var); // expected-error {{const_cast from 'const char *volatile *const volatile *' to 'char **' is not allowed}}
  54   // Different final type.
  55   short ***var3 = const_cast<short***>(var); // expected-error {{const_cast from 'const char *volatile *const volatile *' to 'short ***' is not allowed}}
  56   // Rvalue to reference.
  57   char ***&var4 = const_cast<cpppr>(&var2); // expected-error {{const_cast from rvalue to reference type 'cpppr'}}
  58   // Non-pointer.
  59   char v = const_cast<char>(**var2); // expected-error {{const_cast to 'char', which is not a reference, pointer-to-object, or pointer-to-data-member}}
  60   const int *ar[100] = {0};
  61   extern const int *aub[];
  62   // const_cast looks through arrays as of DR330.
  63   (void) const_cast<int *(*)[100]>(&ar); // ok
  64   (void) const_cast<int *(*)[]>(&aub); // ok
  65   // ... but the array bound must exactly match.
  66   (void) const_cast<int *(*)[]>(&ar); // expected-error {{const_cast from 'const int *(*)[100]' to 'int *(*)[]' is not allowed}}
  67   (void) const_cast<int *(*)[99]>(&ar); // expected-error {{const_cast from 'const int *(*)[100]' to 'int *(*)[99]' is not allowed}}
  68   (void) const_cast<int *(*)[100]>(&aub); // expected-error {{const_cast from 'const int *(*)[]' to 'int *(*)[100]' is not allowed}}
  69   f fp1 = 0;
  70   // Function pointers.
  71   f fp2 = const_cast<f>(fp1); // expected-error {{const_cast to 'f' (aka 'int (*)(int)'), which is not a reference, pointer-to-object, or pointer-to-data-member}}
  72   void (A::*mfn)() = 0;
  73   (void)const_cast<void (A::*)()>(mfn); // expected-error-re {{const_cast to 'void (A::*)(){{( __attribute__\(\(thiscall\)\))?}}', which is not a reference, pointer-to-object, or pointer-to-data-member}}
  74   (void)const_cast<int&&>(0); // expected-error {{const_cast from rvalue to reference type 'int &&'}}
  75 #if __cplusplus <= 199711L // C++03 or earlier modes
  76   // expected-warning@-2 {{rvalue references are a C++11 extension}}
  77 #endif
  78   return **var3;
  79 }
  80
  81 template <typename T>
  82 char *PR21845() { return const_cast<char *>((void)T::x); } // expected-error {{const_cast from 'void' to 'char *' is not allowed}}