[Bug c++/59526] New: [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[bootsarehax at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

            Bug ID: 59526
           Summary: [C++11] Defaulted special member functions don't
                    accept noexcept if a member has a non-trivial noexcept
                    operator in the corresponding special member function
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bootsarehax at gmail dot com

The following code fails for struct X on gcc 4.8.2 with:

bla.cpp:15:3: error: function ‘X::X()’ defaulted on its first declaration with
an exception-specification that differs from the implicit declaration ‘X::X()’
   X() noexcept = default;

bla.cpp:16:6: error: function ‘X& X::operator=(X&&)’ defaulted on its first
declaration with an exception-specification that differs from the implicit
declaration ‘X& X::operator=(X&&)’
   X& operator=(X&&) noexcept = default;

#include <type_traits>

template<bool b>
struct F {
  F() noexcept(b) {}
  F& operator=(F&&) noexcept(b) {return *this;}
};

struct Simple {
  Simple() noexcept {}
  Simple& operator=(Simple&&) noexcept {return *this;}
};

struct X {
  X() noexcept = default;
  X& operator=(X&&) noexcept = default;
  F<true> f;
};
struct X2 {
  X2() /* noexcept */ = default;
  X2& operator=(X2&&) /* noexcept */ = default;
  F<true> f;
};
struct X3 {
  X3() noexcept = default;
  X3& operator=(X3&&) noexcept = default;
  Simple f;
};

static_assert(std::is_nothrow_constructible<X>::value, "");
static_assert(std::is_nothrow_move_assignable<X>::value, "");
static_assert(std::is_nothrow_constructible<X2>::value, "");
static_assert(std::is_nothrow_move_assignable<X2>::value, "");
static_assert(std::is_nothrow_constructible<X3>::value, "");
static_assert(std::is_nothrow_move_assignable<X3>::value, "");

X2 shows that a noexcept function is implicitly generated. X3 shows that it is
necessary for the noexcept operator to depend on a template parameter to
trigger this behavior.