llvm-project/clang/test/SemaCXX/alias-template.cpp

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// RUN: %clang_cc1 -verify -std=c++11 %s
namespace RedeclAliasTypedef {
template<typename U> using T = int;
template<typename U> using T = int;
template<typename U> using T = T<U>;
}
namespace IllegalTypeIds {
template<typename U> using A = void(int n = 0); // expected-error {{default arguments can only be specified for parameters in a function declaration}}
template<typename U> using B = inline void(int n); // expected-error {{type name does not allow function specifier}}
template<typename U> using C = virtual void(int n); // expected-error {{type name does not allow function specifier}}
template<typename U> using D = explicit void(int n); // expected-error {{type name does not allow function specifier}}
template<typename U> using E = void(int n) throw(); // expected-error {{exception specifications are not allowed in type aliases}}
template<typename U> using F = void(*)(int n) &&; // expected-error {{pointer to function type cannot have '&&' qualifier}}
template<typename U> using G = __thread void(int n); // expected-error {{type name does not allow storage class to be specified}}
template<typename U> using H = constexpr int; // expected-error {{type name does not allow constexpr specifier}}
template<typename U> using Y = void(int n); // ok
template<typename U> using Z = void(int n) &&; // ok
}
namespace IllegalSyntax {
template<typename Z> using ::T = void(int n); // expected-error {{name defined in alias declaration must be an identifier}}
template<typename Z> using operator int = void(int n); // expected-error {{name defined in alias declaration must be an identifier}}
template<typename Z> using typename U = void; // expected-error {{name defined in alias declaration must be an identifier}}
template<typename Z> using typename ::V = void(int n); // expected-error {{name defined in alias declaration must be an identifier}}
template<typename Z> using typename ::operator bool = void(int n); // expected-error {{name defined in alias declaration must be an identifier}}
}
namespace VariableLengthArrays {
template<typename Z> using T = int[42]; // ok
int n = 32;
template<typename Z> using T = int[n]; // expected-error {{variable length array declaration not allowed at file scope}}
const int m = 42;
template<typename Z> using U = int[m]; // expected-note {{previous definition}}
template<typename Z> using U = int[42]; // ok
template<typename Z> using U = int; // expected-error {{type alias template redefinition with different types ('int' vs 'int [42]')}}
}
namespace RedeclFunc {
int f(int, char**);
template<typename Z> using T = int;
T<char> f(int, char **); // ok
}
namespace LookupFilter {
namespace N { template<typename U> using S = int; }
using namespace N;
template<typename U> using S = S<U>*; // ok
}
namespace InFunctions {
template<typename...T> struct S0 {
template<typename Z> using U = T*; // expected-error {{declaration type contains unexpanded parameter pack 'T'}}
U<char> u;
};
template<typename Z> using T1 = int;
template<typename Z> using T2 = int[-1]; // expected-error {{array size is negative}}
template<typename...T> struct S3 { // expected-note {{template parameter is declared here}}
template<typename Z> using T = int; // expected-error {{declaration of 'T' shadows template parameter}}
};
template<typename Z> using Z = Z;
}
namespace ClassNameRedecl {
class C0 {
template<typename U> using C0 = int; // expected-error {{member 'C0' has the same name as its class}}
};
class C1 {
template<typename U> using C1 = C1; // expected-error {{member 'C1' has the same name as its class}}
};
class C2 {
template<typename U> using C0 = C1; // ok
};
template<typename...T> class C3 {
template<typename U> using f = T; // expected-error {{declaration type contains unexpanded parameter pack 'T'}}
};
template<typename T> class C4 { // expected-note {{template parameter is declared here}}
template<typename U> using T = int; // expected-error {{declaration of 'T' shadows template parameter}}
};
class C5 {
class c; // expected-note {{previous definition}}
template<typename U> using c = int; // expected-error {{redefinition of 'c' as different kind of symbol}}
class d; // expected-note {{previous definition}}
template<typename U> using d = d; // expected-error {{redefinition of 'd' as different kind of symbol}}
};
class C6 {
class c { template<typename U> using C6 = int; }; // ok
};
}
class CtorDtorName {
template<typename T> using X = CtorDtorName;
X<int>(); // expected-error {{expected member name}}
~X<int>(); // expected-error {{destructor cannot be declared using a type alias}}
};
namespace TagName {
template<typename Z> using S = struct { int n; }; // expected-error {{cannot be defined}}
template<typename Z> using T = class { int n; }; // expected-error {{cannot be defined}}
template<typename Z> using U = enum { a, b, c }; // expected-error {{cannot be defined}}
template<typename Z> using V = struct V { int n; }; // expected-error {{'TagName::V' cannot be defined in a type alias template}}
}
namespace StdExample {
template<typename T, typename U> struct pair;
template<typename T> using handler_t = void (*)(T);
extern handler_t<int> ignore;
extern void (*ignore)(int);
// FIXME: we recover as if cell is an undeclared variable. the diagnostics are terrible!
template<typename T> using cell = pair<T*, cell<T>*>; // expected-error {{use of undeclared identifier 'cell'}} \
expected-error {{'T' does not refer to a value}} \
expected-note {{declared here}} \
expected-error {{expected ';' after alias declaration}}
}
namespace Access {
class C0 {
template<typename Z> using U = int; // expected-note {{declared private here}}
};
C0::U<int> v; // expected-error {{'U' is a private member}}
class C1 {
public:
template<typename Z> using U = int;
};
C1::U<int> w; // ok
}
namespace VoidArg {
template<typename Z> using V = void;
V<int> f(int); // ok
V<char> g(V<double>); // ok (DR577)
}
namespace Curried {
template<typename T, typename U> struct S;
template<typename T> template<typename U> using SS = S<T, U>; // expected-error {{extraneous template parameter list in alias template declaration}}
}
// PR12647
namespace SFINAE {
template<bool> struct enable_if; // expected-note 2{{here}}
template<> struct enable_if<true> { using type = void; };
template<typename T> struct is_enum { static constexpr bool value = __is_enum(T); };
template<typename T> using EnableIf = typename enable_if<T::value>::type; // expected-error {{undefined template}}
template<typename T> using DisableIf = typename enable_if<!T::value>::type; // expected-error {{undefined template}}
template<typename T> EnableIf<is_enum<T>> f();
template<typename T> DisableIf<is_enum<T>> f();
enum E { e };
int main() {
f<int>();
f<E>();
}
template<typename T, typename U = EnableIf<is_enum<T>>> struct fail1 {}; // expected-note {{here}}
template<typename T> struct fail2 : DisableIf<is_enum<T>> {}; // expected-note {{here}}
fail1<int> f1; // expected-note {{here}}
fail2<E> f2; // expected-note {{here}}
}
namespace PR24212 {
struct X {};
template <int I>
struct S {
template <int J>
using T = X[J];
using U = T<I>;
};
static_assert(__is_same(S<3>::U, X[2]), ""); // expected-error {{static_assert failed}}
}