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// DR 339

//

// Test of the use of the comma operator with SFINAE

// Boilerplate helpers

typedef char yes_type;

struct no_type { char data[2]; };

template T create_a();

template struct type { };

template struct enable_if { typedef T type; };

template struct enable_if { };

#define JOIN( X, Y ) DO_JOIN( X, Y )

#define DO_JOIN( X, Y ) DO_JOIN2(X,Y)

#define DO_JOIN2( X, Y ) X##Y

template

  typename enable_if<(sizeof(create_a(), create_a()) > 0),

                     yes_type>::type

  check_comma(int);

template no_type check_comma(...);

template

struct has_comma

{

  static const bool value =

    (sizeof(check_comma(0)) == sizeof(yes_type));

};

#ifdef __GXX_EXPERIMENTAL_CXX0X__

#  define STATIC_ASSERT(Expr) static_assert(Expr, #Expr)

#else

#  define STATIC_ASSERT(Expr) int JOIN(a,__LINE__)[Expr? 1 : -1]

#endif

struct X { };

struct Y { };

struct Z { };

bool operator,(X&, Y);

bool operator,(X, Z);

void operator,(const Y&, const Z&);

STATIC_ASSERT((has_comma::value));

STATIC_ASSERT((has_comma::value));

STATIC_ASSERT((has_comma::value));

STATIC_ASSERT((has_comma::value));

STATIC_ASSERT((has_comma::value));

STATIC_ASSERT((has_comma::value));

STATIC_ASSERT((!has_comma::value));