clang/test/SemaCXX/implicit-exception-spec.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -fcxx-exceptions -verify -std=c++11 -Wall -Wno-unused-local-typedefs %s
   2
   3 template<bool b> struct ExceptionIf { static int f(); };
   4 template<> struct ExceptionIf<false> { typedef int f; };
   5
   6 // The exception specification of a defaulted default constructor depends on
   7 // the contents of in-class member initializers. However, the in-class member
   8 // initializers can depend on the exception specification of the constructor,
   9 // since the class is considered complete within them. We reject any such cases.
  10 namespace InClassInitializers {
  11   // Noexcept::Noexcept() is implicitly declared as noexcept(false), because it
  12   // directly invokes ThrowSomething(). However...
  13   //
  14   // If noexcept(Noexcept()) is false, then Noexcept() is a constant expression,
  15   // so noexcept(Noexcept()) is true. But if noexcept(Noexcept()) is true, then
  16   // Noexcept::Noexcept is not declared constexpr, therefore noexcept(Noexcept())
  17   // is false.
  18   bool ThrowSomething() noexcept(false);
  19   struct ConstExpr { // expected-error {{default member initializer for 'b' needed}}
  20     bool b = // expected-note {{declared here}}
  21       noexcept(ConstExpr()) && ThrowSomething(); // expected-note {{in evaluation of exception spec}}
  22   };
  23
  24   // Much more obviously broken: we can't parse the initializer without already
  25   // knowing whether it produces a noexcept expression.
  26   struct TemplateArg { // expected-error {{default member initializer for 'n' needed}}
  27     int n = // expected-note {{declared here}}
  28       ExceptionIf<noexcept(TemplateArg())>::f(); // expected-note {{in evaluation of exception spec}}
  29   };
  30
  31   // And within a nested class.
  32   struct Nested {
  33     struct Inner { // expected-error {{default member initializer for 'n' needed}}
  34       int n = // expected-note {{declared here}}
  35         ExceptionIf<noexcept(Nested())>::f(); // expected-note {{in evaluation of exception spec}}
  36     } inner; // expected-note {{in evaluation of exception spec}}
  37   };
  38
  39   struct Nested2 {
  40     struct Inner;
  41     int n = Inner().n; // expected-note {{in evaluation of exception spec}}
  42     struct Inner { // expected-error {{initializer for 'n' needed}}
  43       int n = ExceptionIf<noexcept(Nested2())>::f(); // expected-note {{declared here}}
  44     } inner;
  45   };
  46 }
  47
  48 namespace ExceptionSpecification {
  49   struct Nested {
  50     struct T {
  51       T() noexcept(!noexcept(Nested())); // expected-note {{in evaluation of exception spec}}
  52     } t; // expected-error{{exception specification is not available until end of class definition}}
  53   };
  54 }
  55
  56 namespace DefaultArgument {
  57   // FIXME: We should detect and diagnose the cyclic dependence of
  58   // noexcept(Default()) on itself here.
  59   struct Default {
  60     struct T {
  61       T(int = ExceptionIf<noexcept(Default())>::f());
  62     } t;
  63   };
  64 }
  65
  66 namespace ImplicitDtorExceptionSpec {
  67   struct A {
  68     virtual ~A();
  69
  70     struct Inner {
  71       ~Inner() throw();
  72     };
  73     Inner inner;
  74   };
  75
  76   struct B {
  77     virtual ~B() {} // expected-note {{here}}
  78   };
  79
  80   struct C : B {
  81     virtual ~C() {}
  82     A a;
  83   };
  84
  85   struct D : B {
  86     ~D(); // expected-error {{more lax than base}}
  87     struct E {
  88       ~E();
  89       struct F {
  90         ~F() throw(A);
  91       } f;
  92     } e;
  93   };
  94 }
  95
  96 struct nothrow_t {} nothrow;
  97 void *operator new(decltype(sizeof(0)), nothrow_t) noexcept;
  98
  99 namespace PotentiallyConstructed {
 100   template<bool NE> struct A {
 101     A() noexcept(NE);
 102     A(const A&) noexcept(NE);
 103     A(A&&) noexcept(NE);
 104     A &operator=(const A&) noexcept(NE);
 105     A &operator=(A&&) noexcept(NE);
 106     ~A() noexcept(NE);
 107   };
 108
 109   template<bool NE> struct B : virtual A<NE> {};
 110
 111   template<bool NE> struct C : virtual A<NE> {
 112     virtual void f() = 0; // expected-note 2{{unimplemented}}
 113   };
 114
 115   template<bool NE> struct D final : C<NE> {
 116     void f();
 117   };
 118
 119   template<typename T, bool A, bool B, bool C, bool D, bool E, bool F> void check() {
 120     T *p = nullptr;
 121     T &a = *p;
 122     static_assert(noexcept(a = a) == D, "");
 123     static_assert(noexcept(a = static_cast<T&&>(a)) == E, "");
 124     static_assert(noexcept(delete &a) == F, "");
 125
 126     // These are last because the first failure here causes instantiation to bail out.
 127     static_assert(noexcept(new (nothrow) T()) == A, ""); // expected-error 2{{abstract}}
 128     static_assert(noexcept(new (nothrow) T(a)) == B, "");
 129     static_assert(noexcept(new (nothrow) T(static_cast<T&&>(a))) == C, "");
 130   }
 131
 132   template void check<A<false>, 0, 0, 0, 0, 0, 0>();
 133   template void check<A<true >, 1, 1, 1, 1, 1, 1>();
 134   template void check<B<false>, 0, 0, 0, 0, 0, 0>();
 135   template void check<B<true >, 1, 1, 1, 1, 1, 1>();
 136   template void check<C<false>, 1, 1, 1, 0, 0, 0>(); // expected-note {{instantiation}}
 137   template void check<C<true >, 1, 1, 1, 1, 1, 1>(); // expected-note {{instantiation}}
 138   template void check<D<false>, 0, 0, 0, 0, 0, 0>();
 139   template void check<D<true >, 1, 1, 1, 1, 1, 1>();
 140
 141   // ... the above trick doesn't work for this case...
 142   struct Cfalse : virtual A<false> {
 143     virtual void f() = 0;
 144
 145     Cfalse() noexcept;
 146     Cfalse(const Cfalse&) noexcept;
 147     Cfalse(Cfalse&&) noexcept;
 148   };
 149   Cfalse::Cfalse() noexcept = default;
 150   Cfalse::Cfalse(const Cfalse&) noexcept = default;
 151   Cfalse::Cfalse(Cfalse&&) noexcept = default;
 152 }