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llvm-project/clang/test/SemaCXX/expression-traits.cpp

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// RUN: %clang_cc1 -fsyntax-only -verify -fcxx-exceptions %s
//
// Tests for "expression traits" intrinsics such as __is_lvalue_expr.
//
// For the time being, these tests are written against the 2003 C++
// standard (ISO/IEC 14882:2003 -- see draft at
// http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2001/n1316/).
//
// C++0x has its own, more-refined, idea of lvalues and rvalues.
// If/when we need to support those, we'll need to track both
// standard documents.
#if !__has_feature(cxx_static_assert)
# define CONCAT_(X_, Y_) CONCAT1_(X_, Y_)
# define CONCAT1_(X_, Y_) X_ ## Y_
// This emulation can be used multiple times on one line (and thus in
// a macro), except at class scope
# define static_assert(b_, m_) \
typedef int CONCAT_(sa_, __LINE__)[b_ ? 1 : -1]
#endif
// Tests are broken down according to section of the C++03 standard
// (ISO/IEC 14882:2003(E))
// Assertion macros encoding the following two paragraphs
//
// basic.lval/1 Every expression is either an lvalue or an rvalue.
//
// expr.prim/5 A parenthesized expression is a primary expression whose type
// and value are identical to those of the enclosed expression. The
// presence of parentheses does not affect whether the expression is
// an lvalue.
//
// Note: these asserts cannot be made at class scope in C++03. Put
// them in a member function instead.
#define ASSERT_LVALUE(expr) \
static_assert(__is_lvalue_expr(expr), "should be an lvalue"); \
static_assert(__is_lvalue_expr((expr)), \
"the presence of parentheses should have" \
" no effect on lvalueness (expr.prim/5)"); \
static_assert(!__is_rvalue_expr(expr), "should be an lvalue"); \
static_assert(!__is_rvalue_expr((expr)), \
"the presence of parentheses should have" \
" no effect on lvalueness (expr.prim/5)")
#define ASSERT_RVALUE(expr); \
static_assert(__is_rvalue_expr(expr), "should be an rvalue"); \
static_assert(__is_rvalue_expr((expr)), \
"the presence of parentheses should have" \
" no effect on lvalueness (expr.prim/5)"); \
static_assert(!__is_lvalue_expr(expr), "should be an rvalue"); \
static_assert(!__is_lvalue_expr((expr)), \
"the presence of parentheses should have" \
" no effect on lvalueness (expr.prim/5)")
enum Enum { Enumerator };
int ReturnInt();
void ReturnVoid();
Enum ReturnEnum();
void basic_lval_5()
{
// basic.lval/5: The result of calling a function that does not return
// a reference is an rvalue.
ASSERT_RVALUE(ReturnInt());
ASSERT_RVALUE(ReturnVoid());
ASSERT_RVALUE(ReturnEnum());
}
int& ReturnIntReference();
extern Enum& ReturnEnumReference();
void basic_lval_6()
{
// basic.lval/6: An expression which holds a temporary object resulting
// from a cast to a nonreference type is an rvalue (this includes
// the explicit creation of an object using functional notation
struct IntClass
{
explicit IntClass(int = 0);
IntClass(char const*);
operator int() const;
};
struct ConvertibleToIntClass
{
operator IntClass() const;
};
ConvertibleToIntClass b;
// Make sure even trivial conversions are not detected as lvalues
int intLvalue = 0;
ASSERT_RVALUE((int)intLvalue);
ASSERT_RVALUE((short)intLvalue);
ASSERT_RVALUE((long)intLvalue);
// Same tests with function-call notation
ASSERT_RVALUE(int(intLvalue));
ASSERT_RVALUE(short(intLvalue));
ASSERT_RVALUE(long(intLvalue));
char charLValue = 'x';
ASSERT_RVALUE((signed char)charLValue);
ASSERT_RVALUE((unsigned char)charLValue);
ASSERT_RVALUE(static_cast<int>(IntClass()));
IntClass intClassLValue;
ASSERT_RVALUE(static_cast<int>(intClassLValue));
ASSERT_RVALUE(static_cast<IntClass>(ConvertibleToIntClass()));
ConvertibleToIntClass convertibleToIntClassLValue;
ASSERT_RVALUE(static_cast<IntClass>(convertibleToIntClassLValue));
typedef signed char signed_char;
typedef unsigned char unsigned_char;
ASSERT_RVALUE(signed_char(charLValue));
ASSERT_RVALUE(unsigned_char(charLValue));
ASSERT_RVALUE(int(IntClass()));
ASSERT_RVALUE(int(intClassLValue));
ASSERT_RVALUE(IntClass(ConvertibleToIntClass()));
ASSERT_RVALUE(IntClass(convertibleToIntClassLValue));
}
void conv_ptr_1()
{
// conv.ptr/1: A null pointer constant is an integral constant
// expression (5.19) rvalue of integer type that evaluates to
// zero.
ASSERT_RVALUE(0);
}
void expr_6()
{
// expr/6: If an expression initially has the type “reference to T”
// (8.3.2, 8.5.3), ... the expression is an lvalue.
int x = 0;
int& referenceToInt = x;
ASSERT_LVALUE(referenceToInt);
ASSERT_LVALUE(ReturnIntReference());
}
void expr_prim_2()
{
// 5.1/2 A string literal is an lvalue; all other
// literals are rvalues.
ASSERT_LVALUE("foo");
ASSERT_RVALUE(1);
ASSERT_RVALUE(1.2);
ASSERT_RVALUE(10UL);
}
void expr_prim_3()
{
// 5.1/3: The keyword "this" names a pointer to the object for
// which a nonstatic member function (9.3.2) is invoked. ...The
// expression is an rvalue.
struct ThisTest
{
void f() { ASSERT_RVALUE(this); }
};
}
extern int variable;
void Function();
struct BaseClass
{
virtual ~BaseClass();
int BaseNonstaticMemberFunction();
static int BaseStaticMemberFunction();
int baseDataMember;
};
struct Class : BaseClass
{
static void function();
static int variable;
template <class T>
struct NestedClassTemplate {};
template <class T>
static int& NestedFuncTemplate() { return variable; } // expected-note{{candidate function}}
template <class T>
int& NestedMemfunTemplate() { return variable; }
int operator*() const;
template <class T>
int operator+(T) const;
int NonstaticMemberFunction();
static int StaticMemberFunction();
int dataMember;
int& referenceDataMember;
static int& staticReferenceDataMember;
static int staticNonreferenceDataMember;
enum Enum { Enumerator };
operator long() const;
Class();
Class(int,int);
void expr_prim_4()
{
// 5.1/4: The operator :: followed by an identifier, a
// qualified-id, or an operator-function-id is a primary-
// expression. ...The result is an lvalue if the entity is
// a function or variable.
ASSERT_LVALUE(::Function); // identifier: function
ASSERT_LVALUE(::variable); // identifier: variable
// the only qualified-id form that can start without "::" (and thus
// be legal after "::" ) is
//
// ::<sub>opt</sub> nested-name-specifier template<sub>opt</sub> unqualified-id
ASSERT_LVALUE(::Class::function); // qualified-id: function
ASSERT_LVALUE(::Class::variable); // qualified-id: variable
// The standard doesn't give a clear answer about whether these
// should really be lvalues or rvalues without some surrounding
// context that forces them to be interpreted as naming a
// particular function template specialization (that situation
// doesn't come up in legal pure C++ programs). This language
// extension simply rejects them as requiring additional context
__is_lvalue_expr(::Class::NestedFuncTemplate); // qualified-id: template \
// expected-error{{cannot resolve overloaded function 'NestedFuncTemplate' from context}}
__is_lvalue_expr(::Class::NestedMemfunTemplate); // qualified-id: template \
// expected-error{{a bound member function may only be called}}
__is_lvalue_expr(::Class::operator+); // operator-function-id: template \
// expected-error{{a bound member function may only be called}}
//ASSERT_RVALUE(::Class::operator*); // operator-function-id: member function
}
void expr_prim_7()
{
// expr.prim/7 An identifier is an id-expression provided it has been
// suitably declared (clause 7). [Note: ... ] The type of the
// expression is the type of the identifier. The result is the
// entity denoted by the identifier. The result is an lvalue if
// the entity is a function, variable, or data member... (cont'd)
ASSERT_LVALUE(Function); // identifier: function
ASSERT_LVALUE(StaticMemberFunction); // identifier: function
ASSERT_LVALUE(variable); // identifier: variable
ASSERT_LVALUE(dataMember); // identifier: data member
//ASSERT_RVALUE(NonstaticMemberFunction); // identifier: member function
// (cont'd)...A nested-name-specifier that names a class,
// optionally followed by the keyword template (14.2), and then
// followed by the name of a member of either that class (9.2) or
// one of its base classes... is a qualified-id... The result is
// the member. The type of the result is the type of the
// member. The result is an lvalue if the member is a static
// member function or a data member.
ASSERT_LVALUE(Class::dataMember);
ASSERT_LVALUE(Class::StaticMemberFunction);
//ASSERT_RVALUE(Class::NonstaticMemberFunction); // identifier: member function
ASSERT_LVALUE(Class::baseDataMember);
ASSERT_LVALUE(Class::BaseStaticMemberFunction);
//ASSERT_RVALUE(Class::BaseNonstaticMemberFunction); // identifier: member function
}
};
void expr_call_10()
{
// expr.call/10: A function call is an lvalue if and only if the
// result type is a reference. This statement is partially
// redundant with basic.lval/5
basic_lval_5();
ASSERT_LVALUE(ReturnIntReference());
ASSERT_LVALUE(ReturnEnumReference());
}
namespace Namespace
{
int x;
void function();
}
void expr_prim_8()
{
// expr.prim/8 A nested-name-specifier that names a namespace
// (7.3), followed by the name of a member of that namespace (or
// the name of a member of a namespace made visible by a
// using-directive ) is a qualified-id; 3.4.3.2 describes name
// lookup for namespace members that appear in qualified-ids. The
// result is the member. The type of the result is the type of the
// member. The result is an lvalue if the member is a function or
// a variable.
ASSERT_LVALUE(Namespace::x);
ASSERT_LVALUE(Namespace::function);
}
void expr_sub_1(int* pointer)
{
// expr.sub/1 A postfix expression followed by an expression in
// square brackets is a postfix expression. One of the expressions
// shall have the type “pointer to T” and the other shall have
// enumeration or integral type. The result is an lvalue of type
// “T.”
ASSERT_LVALUE(pointer[1]);
// The expression E1[E2] is identical (by definition) to *((E1)+(E2)).
ASSERT_LVALUE(*(pointer+1));
}
void expr_type_conv_1()
{
// expr.type.conv/1 A simple-type-specifier (7.1.5) followed by a
// parenthesized expression-list constructs a value of the specified
// type given the expression list. ... If the expression list
// specifies more than a single value, the type shall be a class with
// a suitably declared constructor (8.5, 12.1), and the expression
// T(x1, x2, ...) is equivalent in effect to the declaration T t(x1,
// x2, ...); for some invented temporary variable t, with the result
// being the value of t as an rvalue.
ASSERT_RVALUE(Class(2,2));
}
void expr_type_conv_2()
{
// expr.type.conv/2 The expression T(), where T is a
// simple-type-specifier (7.1.5.2) for a non-array complete object
// type or the (possibly cv-qualified) void type, creates an
// rvalue of the specified type,
ASSERT_RVALUE(int());
ASSERT_RVALUE(Class());
ASSERT_RVALUE(void());
}
void expr_ref_4()
{
// Applies to expressions of the form E1.E2
// If E2 is declared to have type “reference to T”, then E1.E2 is
// an lvalue;.... Otherwise, one of the following rules applies.
ASSERT_LVALUE(Class().staticReferenceDataMember);
ASSERT_LVALUE(Class().referenceDataMember);
// — If E2 is a static data member, and the type of E2 is T, then
// E1.E2 is an lvalue; ...
ASSERT_LVALUE(Class().staticNonreferenceDataMember);
ASSERT_LVALUE(Class().staticReferenceDataMember);
// — If E2 is a non-static data member, ... If E1 is an lvalue,
// then E1.E2 is an lvalue...
Class lvalue;
ASSERT_LVALUE(lvalue.dataMember);
ASSERT_RVALUE(Class().dataMember);
// — If E1.E2 refers to a static member function, ... then E1.E2
// is an lvalue
ASSERT_LVALUE(Class().StaticMemberFunction);
// — Otherwise, if E1.E2 refers to a non-static member function,
// then E1.E2 is not an lvalue.
//ASSERT_RVALUE(Class().NonstaticMemberFunction);
// — If E2 is a member enumerator, and the type of E2 is T, the
// expression E1.E2 is not an lvalue. The type of E1.E2 is T.
ASSERT_RVALUE(Class().Enumerator);
ASSERT_RVALUE(lvalue.Enumerator);
}
void expr_post_incr_1(int x)
{
// expr.post.incr/1 The value obtained by applying a postfix ++ is
// the value that the operand had before applying the
// operator... The result is an rvalue.
ASSERT_RVALUE(x++);
}
void expr_dynamic_cast_2()
{
// expr.dynamic.cast/2: If T is a pointer type, v shall be an
// rvalue of a pointer to complete class type, and the result is
// an rvalue of type T.
Class instance;
ASSERT_RVALUE(dynamic_cast<Class*>(&instance));
// If T is a reference type, v shall be an
// lvalue of a complete class type, and the result is an lvalue of
// the type referred to by T.
ASSERT_LVALUE(dynamic_cast<Class&>(instance));
}
void expr_dynamic_cast_5()
{
// expr.dynamic.cast/5: If T is “reference to cv1 B” and v has type
// “cv2 D” such that B is a base class of D, the result is an
// lvalue for the unique B sub-object of the D object referred
// to by v.
typedef BaseClass B;
typedef Class D;
D object;
ASSERT_LVALUE(dynamic_cast<B&>(object));
}
// expr.dynamic.cast/8: The run-time check logically executes as follows:
//
// — If, in the most derived object pointed (referred) to by v, v
// points (refers) to a public base class subobject of a T object, and
// if only one object of type T is derived from the sub-object pointed
// (referred) to by v, the result is a pointer (an lvalue referring)
// to that T object.
//
// — Otherwise, if v points (refers) to a public base class sub-object
// of the most derived object, and the type of the most derived object
// has a base class, of type T, that is unambiguous and public, the
// result is a pointer (an lvalue referring) to the T sub-object of
// the most derived object.
//
// The mention of "lvalue" in the text above appears to be a
// defect that is being corrected by the response to UK65 (see
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2841.html).
#if 0
void expr_typeid_1()
{
// expr.typeid/1: The result of a typeid expression is an lvalue...
ASSERT_LVALUE(typeid(1));
}
#endif
void expr_static_cast_1(int x)
{
// expr.static.cast/1: The result of the expression
// static_cast<T>(v) is the result of converting the expression v
// to type T. If T is a reference type, the result is an lvalue;
// otherwise, the result is an rvalue.
ASSERT_LVALUE(static_cast<int&>(x));
ASSERT_RVALUE(static_cast<int>(x));
}
void expr_reinterpret_cast_1()
{
// expr.reinterpret.cast/1: The result of the expression
// reinterpret_cast<T>(v) is the result of converting the
// expression v to type T. If T is a reference type, the result is
// an lvalue; otherwise, the result is an rvalue
ASSERT_RVALUE(reinterpret_cast<int*>(0));
char const v = 0;
ASSERT_LVALUE(reinterpret_cast<char const&>(v));
}
void expr_unary_op_1(int* pointer, struct incomplete* pointerToIncompleteType)
{
// expr.unary.op/1: The unary * operator performs indirection: the
// expression to which it is applied shall be a pointer to an
// object type, or a pointer to a function type and the result is
// an lvalue referring to the object or function to which the
// expression points.
ASSERT_LVALUE(*pointer);
ASSERT_LVALUE(*Function);
// [Note: a pointer to an incomplete type
// (other than cv void ) can be dereferenced. ]
ASSERT_LVALUE(*pointerToIncompleteType);
}
void expr_pre_incr_1(int operand)
{
// expr.pre.incr/1: The operand of prefix ++ ... shall be a
// modifiable lvalue.... The value is the new value of the
// operand; it is an lvalue.
ASSERT_LVALUE(++operand);
}
void expr_cast_1(int x)
{
// expr.cast/1: The result of the expression (T) cast-expression
// is of type T. The result is an lvalue if T is a reference type,
// otherwise the result is an rvalue.
ASSERT_LVALUE((void(&)())expr_cast_1);
ASSERT_LVALUE((int&)x);
ASSERT_RVALUE((void(*)())expr_cast_1);
ASSERT_RVALUE((int)x);
}
void expr_mptr_oper()
{
// expr.mptr.oper/6: The result of a .* expression is an lvalue
// only if its first operand is an lvalue and its second operand
// is a pointer to data member... (cont'd)
typedef Class MakeRValue;
ASSERT_RVALUE(MakeRValue().*(&Class::dataMember));
//ASSERT_RVALUE(MakeRValue().*(&Class::NonstaticMemberFunction));
Class lvalue;
ASSERT_LVALUE(lvalue.*(&Class::dataMember));
//ASSERT_RVALUE(lvalue.*(&Class::NonstaticMemberFunction));
// (cont'd)...The result of an ->* expression is an lvalue only
// if its second operand is a pointer to data member. If the
// second operand is the null pointer to member value (4.11), the
// behavior is undefined.
ASSERT_LVALUE((&lvalue)->*(&Class::dataMember));
//ASSERT_RVALUE((&lvalue)->*(&Class::NonstaticMemberFunction));
}
void expr_cond(bool cond)
{
// 5.16 Conditional operator [expr.cond]
//
// 2 If either the second or the third operand has type (possibly
// cv-qualified) void, then the lvalue-to-rvalue (4.1),
// array-to-pointer (4.2), and function-to-pointer (4.3) standard
// conversions are performed on the second and third operands, and one
// of the following shall hold:
//
// — The second or the third operand (but not both) is a
// throw-expression (15.1); the result is of the type of the other and
// is an rvalue.
Class classLvalue;
ASSERT_RVALUE(cond ? throw 1 : (void)0);
ASSERT_RVALUE(cond ? (void)0 : throw 1);
ASSERT_RVALUE(cond ? throw 1 : classLvalue);
ASSERT_RVALUE(cond ? classLvalue : throw 1);
// — Both the second and the third operands have type void; the result
// is of type void and is an rvalue. [Note: this includes the case
// where both operands are throw-expressions. ]
ASSERT_RVALUE(cond ? (void)1 : (void)0);
ASSERT_RVALUE(cond ? throw 1 : throw 0);
// expr.cond/4: If the second and third operands are lvalues and
// have the same type, the result is of that type and is an
// lvalue.
ASSERT_LVALUE(cond ? classLvalue : classLvalue);
int intLvalue = 0;
ASSERT_LVALUE(cond ? intLvalue : intLvalue);
// expr.cond/5:Otherwise, the result is an rvalue.
typedef Class MakeRValue;
ASSERT_RVALUE(cond ? MakeRValue() : classLvalue);
ASSERT_RVALUE(cond ? classLvalue : MakeRValue());
ASSERT_RVALUE(cond ? MakeRValue() : MakeRValue());
ASSERT_RVALUE(cond ? classLvalue : intLvalue);
ASSERT_RVALUE(cond ? intLvalue : int());
}
void expr_ass_1(int x)
{
// expr.ass/1: There are several assignment operators, all of
// which group right-to-left. All require a modifiable lvalue as
// their left operand, and the type of an assignment expression is
// that of its left operand. The result of the assignment
// operation is the value stored in the left operand after the
// assignment has taken place; the result is an lvalue.
ASSERT_LVALUE(x = 1);
ASSERT_LVALUE(x += 1);
ASSERT_LVALUE(x -= 1);
ASSERT_LVALUE(x *= 1);
ASSERT_LVALUE(x /= 1);
ASSERT_LVALUE(x %= 1);
ASSERT_LVALUE(x ^= 1);
ASSERT_LVALUE(x &= 1);
ASSERT_LVALUE(x |= 1);
}
void expr_comma(int x)
{
// expr.comma: A pair of expressions separated by a comma is
// evaluated left-to-right and the value of the left expression is
// discarded... result is an lvalue if its right operand is.
// Can't use the ASSERT_XXXX macros without adding parens around
// the comma expression.
static_assert(__is_lvalue_expr(x,x), "expected an lvalue");
static_assert(__is_rvalue_expr(x,1), "expected an rvalue");
static_assert(__is_lvalue_expr(1,x), "expected an lvalue");
static_assert(__is_rvalue_expr(1,1), "expected an rvalue");
}
#if 0
template<typename T> void f();
// FIXME These currently fail
void expr_fun_lvalue()
{
ASSERT_LVALUE(&f<int>);
}
void expr_fun_rvalue()
{
ASSERT_RVALUE(f<int>);
}
#endif
template <int NonTypeNonReferenceParameter, int& NonTypeReferenceParameter>
void check_temp_param_6()
{
ASSERT_RVALUE(NonTypeNonReferenceParameter);
ASSERT_LVALUE(NonTypeReferenceParameter);
}
int AnInt = 0;
void temp_param_6()
{
check_temp_param_6<3,AnInt>();
}
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