Viewing file:  abstract1.C (1.62 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
// { dg-do compile }
// Contributed by <giovannibajo at gcc dot gnu dot org>,
// <pavel_vozenilek at hotmail dot com>,
// <bangerth at dealii dot org>
// c++/9256: Make sure that a pointer to an array of abstract elements
// cannot be created, not even during template substitution (DR337).
// Changed massively by P0929R2: now only creating an object of the array type
// is ill-formed, not merely forming the array type.
struct Abstract { virtual void f() = 0; }; // { dg-message "note" }
struct Complete { void f(); };
/*
* TEST 1
* Arrays of abstract elements cannot be defined.
*/
Abstract a0[2]; // { dg-error "" }
Abstract (*a1)[2];
Abstract (**a2)[2];
Abstract (***a3)[2];
Abstract *a4;
Abstract *a5[2];
Abstract (*a6[2])[2];
Abstract **a7[2];
Abstract *(*a8[2])[2];
Abstract (**a9[2])[2];
/*
* TEST 2
* If an array of abstract elements is created during template
* instantiation, an error should occur.
*/
template <class T> struct K {
T (*a1)[2];
T (a2)[2]; // { dg-error "abstract" }
};
template struct K<Abstract>; // { dg-message "required" }
/*
* TEST 3
* Deducing an array of abstract elements during type deduction is no longer a
* silent failure.
*/
template <bool> struct StaticAssert;
template <> struct StaticAssert<true> {};
typedef char Yes;
typedef struct { char x[2]; } No;
template<typename U> No is_abstract(U (*k)[1]);
template<typename U> Yes is_abstract(...);
StaticAssert<sizeof(is_abstract<Abstract>(0)) == sizeof(No)> b1;
StaticAssert<sizeof(is_abstract<Complete>(0)) == sizeof(No)> b2;
StaticAssert<sizeof(is_abstract<int>(0)) == sizeof(No)> b3;
|
