clang/test/SemaCXX/literal-type.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
   3
   4
   5 static_assert(__is_literal(int), "fail");
   6 static_assert(__is_literal_type(int), "fail"); // alternate spelling for GCC
   7 static_assert(__is_literal(void*), "fail");
   8 enum E { E1 };
   9 static_assert(__is_literal(E), "fail");
  10 static_assert(__is_literal(decltype(E1)), "fail");
  11 typedef int IAR[10];
  12 static_assert(__is_literal(IAR), "fail");
  13 typedef int Vector __attribute__((vector_size(16)));
  14 typedef int VectorExt __attribute__((ext_vector_type(4)));
  15 static_assert(__is_literal(Vector), "fail");
  16 static_assert(__is_literal(VectorExt), "fail");
  17
  18 // C++0x [basic.types]p10:
  19 //   A type is a literal type if it is:
  20 //    [...]
  21 //    -- a class type that has all of the following properties:
  22 //        -- it has a trivial destructor
  23 //        -- every constructor call and full-expression in the
  24 //           brace-or-equal-initializers for non-static data members (if an) is
  25 //           a constant expression,
  26 //        -- it is an aggregate type or has at least one constexpr constructor
  27 //           or constructor template that is not a copy or move constructor, and
  28 //           [DR1452 adds class types with trivial default constructors to
  29 //            this list]
  30 //        -- it has all non-static data members and base classes of literal
  31 //           types
  32 struct Empty {};
  33 struct LiteralType {
  34   int x;
  35   E e;
  36   IAR arr;
  37   Empty empty;
  38   int method();
  39 };
  40 struct HasDtor { ~HasDtor(); };
  41
  42 class NonAggregate { int x; };
  43 struct NonLiteral { NonLiteral(); };
  44 struct HasNonLiteralBase : NonLiteral {};
  45 struct HasNonLiteralMember { HasDtor x; };
  46
  47 static_assert(__is_literal(Empty), "fail");
  48 static_assert(__is_literal(LiteralType), "fail");
  49 static_assert(__is_literal(NonAggregate), "fail");
  50 static_assert(!__is_literal(NonLiteral), "fail");
  51 static_assert(!__is_literal(HasDtor), "fail");
  52 static_assert(!__is_literal(HasNonLiteralBase), "fail");
  53 static_assert(!__is_literal(HasNonLiteralMember), "fail");
  54
  55 // DR1361 removes the brace-or-equal-initializer bullet so that we can allow:
  56 extern int f(); // expected-note {{here}}
  57 struct HasNonConstExprMemInit {
  58   int x = f(); // expected-note {{non-constexpr function}}
  59   constexpr HasNonConstExprMemInit() {} // expected-error {{never produces a constant expression}}
  60   constexpr HasNonConstExprMemInit(int y) : x(y) {} // ok
  61 };
  62 static_assert(__is_literal(HasNonConstExprMemInit), "fail");
  63
  64 class HasConstExprCtor {
  65   int x;
  66 public:
  67   constexpr HasConstExprCtor(int x) : x(x) {}
  68 };
  69 template <typename T> class HasConstExprCtorTemplate {
  70   T x;
  71 public:
  72   template <typename U> constexpr HasConstExprCtorTemplate(U y) : x(y) {}
  73 };
  74 template <typename T> class HasConstExprCtorT {
  75   constexpr HasConstExprCtorT(T) {}
  76 };
  77 static_assert(__is_literal(HasConstExprCtor), "fail");
  78 static_assert(__is_literal(HasConstExprCtorTemplate<int>), "fail");
  79 static_assert(__is_literal(HasConstExprCtorT<NonLiteral>), "fail");
  80
  81
  82 #if __cplusplus >= 202003L
  83 namespace GH77924 {
  84
  85 struct A { A(); };
  86 template <class T>
  87 struct opt {
  88   union Data {
  89       constexpr Data() : x{} {}
  90       constexpr ~Data() {}
  91       char x;
  92       T data;
  93   };
  94
  95   constexpr opt() : data{} {}
  96   constexpr ~opt() { if (engaged) data.data.~T(); }
  97   Data data;
  98   bool engaged = false;
  99 };
 100
 101 consteval void foo() {
 102   opt<A> a;
 103 }
 104
 105 void test() {
 106   foo();
 107 }
 108
 109 }
 110 #endif