clang/test/SemaCXX/rval-references.cpp

   1 // RUN: %clang_cc1 -fcxx-exceptions -fexceptions -fsyntax-only  -verify -std=c++11 %s
   2
   3 typedef int&& irr;
   4 typedef irr& ilr_c1; // Collapses to int&
   5 typedef int& ilr;
   6 typedef ilr&& ilr_c2; // Collapses to int&
   7
   8 irr ret_irr() {
   9   return 0; // expected-warning {{returning reference to local temporary}}
  10 }
  11
  12 struct not_int {};
  13
  14 int over(int&);
  15 not_int over(int&&);
  16
  17 int over2(const int&);
  18 not_int over2(int&&);
  19
  20 struct conv_to_not_int_rvalue {
  21   operator not_int &&();
  22 };
  23
  24 typedef void (fun_type)();
  25 void fun();
  26 fun_type &&make_fun();
  27
  28 void f() {
  29   int &&virr1; // expected-error {{declaration of reference variable 'virr1' requires an initializer}}
  30   int &&virr2 = 0;
  31   int &&virr3 = virr2; // expected-error {{rvalue reference to type 'int' cannot bind to lvalue of type 'int'}}
  32   int i1 = 0;
  33   const double d1 = 0;
  34   const int ci1 = 1;
  35   int &&virr4 = i1; // expected-error {{rvalue reference to type 'int' cannot bind to lvalue of type 'int'}}
  36   int &&virr5 = ret_irr();
  37   int &&virr6 = static_cast<int&&>(i1);
  38   (void)static_cast<not_int &&>(i1); // expected-error {{reference to type 'not_int' could not bind to an lvalue of type 'int'}}
  39   (void)static_cast<int &&>(static_cast<int const&&>(i1)); // expected-error {{cannot cast from rvalue of type 'const int' to rvalue reference type 'int &&'}}
  40   (void)static_cast<int &&>(ci1);    // expected-error {{types are not compatible}}
  41   (void)static_cast<int &&>(d1);
  42   int i2 = over(i1);
  43   not_int ni1 = over(0);
  44   int i3 = over(virr2);
  45   not_int ni2 = over(ret_irr());
  46
  47   int i4 = over2(i1);
  48   not_int ni3 = over2(0);
  49
  50   ilr_c1 vilr1 = i1;
  51   ilr_c2 vilr2 = i1;
  52
  53   conv_to_not_int_rvalue cnir;
  54   not_int &&ni4 = cnir;
  55   not_int &ni5 = cnir; // expected-error{{non-const lvalue reference to type 'not_int' cannot bind to a value of unrelated type 'conv_to_not_int_rvalue'}}
  56   not_int &&ni6 = conv_to_not_int_rvalue();
  57
  58   fun_type &&fun_ref = fun; // works because functions are special
  59   fun_type &&fun_ref2 = make_fun(); // same
  60   fun_type &fun_lref = make_fun(); // also special
  61
  62   try {
  63   } catch(int&&) { // expected-error {{cannot catch exceptions by rvalue reference}}
  64   }
  65 }
  66
  67 int&& should_warn(int i) {
  68   return static_cast<int&&>(i); // expected-warning {{reference to stack memory associated with parameter 'i' returned}}
  69 }
  70 int&& should_not_warn(int&& i) {
  71   return static_cast<int&&>(i);
  72 }
  73
  74
  75 // Test the return dance. This also tests IsReturnCopyElidable.
  76 struct MoveOnly {
  77   MoveOnly();
  78   MoveOnly(const MoveOnly&) = delete;   // expected-note 3{{explicitly marked deleted here}}
  79 };
  80
  81 MoveOnly gmo;
  82 MoveOnly returningNonEligible() {
  83   static MoveOnly mo;
  84   MoveOnly &r = mo;
  85   if (0) // Copy from global can't be elided
  86     return gmo; // expected-error {{call to deleted constructor}}
  87   else if (0) // Copy from local static can't be elided
  88     return mo; // expected-error {{call to deleted constructor}}
  89   else // Copy from reference can't be elided
  90     return r; // expected-error {{call to deleted constructor}}
  91 }