clang/test/AST/ByteCode/lifetimes.cpp

   1 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify=expected,both %s
   2 // RUN: %clang_cc1 -verify=ref,both %s
   3
   4 /// FIXME: Slight difference in diagnostic output here.
   5
   6 struct Foo {
   7   int a;
   8 };
   9
  10 constexpr int dead1() { // expected-error {{never produces a constant expression}}
  11
  12   Foo *F2 = nullptr;
  13   {
  14     Foo F{12}; // expected-note 2{{declared here}}
  15     F2 = &F;
  16   } // Ends lifetime of F.
  17
  18   return F2->a; // expected-note 2{{read of variable whose lifetime has ended}} \
  19                 // ref-note {{read of object outside its lifetime is not allowed in a constant expression}}
  20 }
  21 static_assert(dead1() == 1, ""); // both-error {{not an integral constant expression}} \
  22                                  // both-note {{in call to}}
  23
  24
  25 struct S {
  26   int &&r; // both-note {{reference member declared here}}
  27   int t;
  28   constexpr S() : r(0), t(r) {} // both-error {{reference member 'r' binds to a temporary object whose lifetime would be shorter than the lifetime of the constructed object}} \
  29                                 // ref-note {{read of object outside its lifetime is not allowed in a constant expression}} \
  30                                 // expected-note {{temporary created here}} \
  31                                 // expected-note {{read of temporary whose lifetime has ended}}
  32 };
  33 constexpr int k1 = S().t; // both-error {{must be initialized by a constant expression}} \
  34                           // ref-note {{in call to}} \
  35                           // expected-note {{in call to}}
  36
  37
  38 namespace MoveFnWorks {
  39   template<typename T> constexpr T &&ref(T &&t) { return (T&&)t; }
  40
  41   struct Buf {};
  42
  43   struct A {
  44     constexpr A(Buf &buf) : buf(buf) { }
  45     Buf &buf;
  46   };
  47
  48   constexpr bool dtor_calls_dtor() {
  49     struct B {
  50       A &&d;
  51       constexpr B(Buf &buf) : d(ref(A(buf))) {}
  52     };
  53
  54     Buf buf;
  55     {
  56       B b(buf);
  57     }
  58
  59     return true;
  60   }
  61   static_assert(dtor_calls_dtor(), "");
  62 }
  63
  64 namespace PrimitiveMoveFn {
  65   /// This used to crash.
  66   void test() {
  67     const float y = 100;
  68     const float &x = y;
  69   }
  70 }