// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s -fno-signed-char
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple aarch64_be-linux-gnu %s
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define LITTLE_END 1
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define LITTLE_END 0
#else
# error "huh?"
#endif
template <class T, class V> struct is_same {
static constexpr bool value = false;
};
template <class T> struct is_same<T, T> {
static constexpr bool value = true;
};
static_assert(sizeof(int) == 4);
static_assert(sizeof(long long) == 8);
template <class To, class From>
constexpr To bit_cast(const From &from) {
static_assert(sizeof(To) == sizeof(From));
// expected-note@+9 {{cannot be represented in type 'bool'}}
#ifdef __x86_64
// expected-note@+7 {{or 'std::byte'; '__int128' is invalid}}
#endif
#ifdef __CHAR_UNSIGNED__
// expected-note@+4 2 {{indeterminate value can only initialize an object of type 'unsigned char', 'char', or 'std::byte'; 'signed char' is invalid}}
#else
// expected-note@+2 2 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'signed char' is invalid}}
#endif
return __builtin_bit_cast(To, from);
}
template <class Intermediate, class Init>
constexpr bool round_trip(const Init &init) {
return bit_cast<Init>(bit_cast<Intermediate>(init)) == init;
}
void test_int() {
static_assert(round_trip<unsigned>((int)-1));
static_assert(round_trip<unsigned>((int)0x12345678));
static_assert(round_trip<unsigned>((int)0x87654321));
static_assert(round_trip<unsigned>((int)0x0C05FEFE));
}
void test_array() {
constexpr unsigned char input[] = {0xCA, 0xFE, 0xBA, 0xBE};
constexpr unsigned expected = LITTLE_END ? 0xBEBAFECA : 0xCAFEBABE;
static_assert(bit_cast<unsigned>(input) == expected);
}
void test_record() {
struct int_splicer {
unsigned x;
unsigned y;
constexpr bool operator==(const int_splicer &other) const {
return other.x == x && other.y == y;
}
};
constexpr int_splicer splice{0x0C05FEFE, 0xCAFEBABE};
static_assert(bit_cast<unsigned long long>(splice) == (LITTLE_END
? 0xCAFEBABE0C05FEFE
: 0x0C05FEFECAFEBABE));
static_assert(bit_cast<int_splicer>(0xCAFEBABE0C05FEFE).x == (LITTLE_END
? 0x0C05FEFE
: 0xCAFEBABE));
static_assert(round_trip<unsigned long long>(splice));
static_assert(round_trip<long long>(splice));
struct base2 {
};
struct base3 {
unsigned z;
};
struct bases : int_splicer, base2, base3 {
unsigned doublez;
};
struct tuple4 {
unsigned x, y, z, doublez;
bool operator==(tuple4 const &other) const = default;
constexpr bool operator==(bases const &other) const {
return x == other.x && y == other.y &&
z == other.z && doublez == other.doublez;
}
};
constexpr bases b = {{1, 2}, {}, {3}, 4};
constexpr tuple4 t4 = bit_cast<tuple4>(b);
static_assert(t4 == tuple4{1, 2, 3, 4});
static_assert(round_trip<tuple4>(b));
constexpr auto b2 = bit_cast<bases>(t4);
static_assert(t4 == b2);
}
void test_partially_initialized() {
struct pad {
signed char x;
int y;
};
struct no_pad {
signed char x;
signed char p1, p2, p3;
int y;
};
static_assert(sizeof(pad) == sizeof(no_pad));
constexpr pad pir{4, 4};
// expected-error@+2 {{constexpr variable 'piw' must be initialized by a constant expression}}
// expected-note@+1 {{in call to 'bit_cast<no_pad, pad>(pir)'}}
constexpr int piw = bit_cast<no_pad>(pir).x;
// expected-error@+2 {{constexpr variable 'bad' must be initialized by a constant expression}}
// expected-note@+1 {{in call to 'bit_cast<no_pad, pad>(pir)'}}
constexpr no_pad bad = bit_cast<no_pad>(pir);
constexpr pad fine = bit_cast<pad>(no_pad{1, 2, 3, 4, 5});
static_assert(fine.x == 1 && fine.y == 5);
}
void no_bitfields() {
// FIXME!
struct S {
unsigned char x : 8;
};
struct G {
unsigned char x : 8;
};
constexpr S s{0};
// expected-error@+2 {{constexpr variable 'g' must be initialized by a constant expression}}
// expected-note@+1 {{constexpr bit_cast involving bit-field is not yet supported}}
constexpr G g = __builtin_bit_cast(G, s);
}
void array_members() {
struct S {
int ar[3];
constexpr bool operator==(const S &rhs) {
return ar[0] == rhs.ar[0] && ar[1] == rhs.ar[1] && ar[2] == rhs.ar[2];
}
};
struct G {
int a, b, c;
constexpr bool operator==(const G &rhs) {
return a == rhs.a && b == rhs.b && c == rhs.c;
}
};
constexpr S s{{1, 2, 3}};
constexpr G g = bit_cast<G>(s);
static_assert(g.a == 1 && g.b == 2 && g.c == 3);
static_assert(round_trip<G>(s));
static_assert(round_trip<S>(g));
}
void bad_types() {
union X {
int x;
};
struct G {
int g;
};
// expected-error@+2 {{constexpr variable 'g' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a union type is not allowed in a constant expression}}
constexpr G g = __builtin_bit_cast(G, X{0});
// expected-error@+2 {{constexpr variable 'x' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast to a union type is not allowed in a constant expression}}
constexpr X x = __builtin_bit_cast(X, G{0});
struct has_pointer {
// expected-note@+1 2 {{invalid type 'int *' is a member of 'has_pointer'}}
int *ptr;
};
// expected-error@+2 {{constexpr variable 'ptr' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a pointer type is not allowed in a constant expression}}
constexpr unsigned long ptr = __builtin_bit_cast(unsigned long, has_pointer{0});
// expected-error@+2 {{constexpr variable 'hptr' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast to a pointer type is not allowed in a constant expression}}
constexpr has_pointer hptr = __builtin_bit_cast(has_pointer, 0ul);
}
void backtrace() {
struct A {
// expected-note@+1 {{invalid type 'int *' is a member of 'A'}}
int *ptr;
};
struct B {
// expected-note@+1 {{invalid type 'A[10]' is a member of 'B'}}
A as[10];
};
// expected-note@+1 {{invalid type 'B' is a base of 'C'}}
struct C : B {
};
struct E {
unsigned long ar[10];
};
// expected-error@+2 {{constexpr variable 'e' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a pointer type is not allowed in a constant expression}}
constexpr E e = __builtin_bit_cast(E, C{});
}
void test_array_fill() {
constexpr unsigned char a[4] = {1, 2};
constexpr unsigned int i = bit_cast<unsigned int>(a);
static_assert(i == (LITTLE_END ? 0x00000201 : 0x01020000));
}
typedef decltype(nullptr) nullptr_t;
#ifdef __CHAR_UNSIGNED__
// expected-note@+5 {{indeterminate value can only initialize an object of type 'unsigned char', 'char', or 'std::byte'; 'unsigned long' is invalid}}
#else
// expected-note@+3 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'unsigned long' is invalid}}
#endif
// expected-error@+1 {{constexpr variable 'test_from_nullptr' must be initialized by a constant expression}}
constexpr unsigned long test_from_nullptr = __builtin_bit_cast(unsigned long, nullptr);
constexpr int test_from_nullptr_pass = (__builtin_bit_cast(unsigned char[8], nullptr), 0);
constexpr int test_to_nullptr() {
nullptr_t npt = __builtin_bit_cast(nullptr_t, 0ul);
struct indet_mem {
unsigned char data[sizeof(void *)];
};
indet_mem im = __builtin_bit_cast(indet_mem, nullptr);
nullptr_t npt2 = __builtin_bit_cast(nullptr_t, im);
return 0;
}
constexpr int ttn = test_to_nullptr();
// expected-warning@+2 {{returning reference to local temporary object}}
// expected-note@+1 {{temporary created here}}
constexpr const long &returns_local() { return 0L; }
// expected-error@+2 {{constexpr variable 'test_nullptr_bad' must be initialized by a constant expression}}
// expected-note@+1 {{read of temporary whose lifetime has ended}}
constexpr nullptr_t test_nullptr_bad = __builtin_bit_cast(nullptr_t, returns_local());
constexpr int test_indeterminate(bool read_indet) {
struct pad {
char a;
int b;
};
struct no_pad {
char a;
unsigned char p1, p2, p3;
int b;
};
pad p{1, 2};
no_pad np = bit_cast<no_pad>(p);
int tmp = np.a + np.b;
unsigned char& indet_ref = np.p1;
if (read_indet) {
// expected-note@+1 {{read of uninitialized object is not allowed in a constant expression}}
tmp = indet_ref;
}
indet_ref = 0;
return 0;
}
constexpr int run_test_indeterminate = test_indeterminate(false);
// expected-error@+2 {{constexpr variable 'run_test_indeterminate2' must be initialized by a constant expression}}
// expected-note@+1 {{in call to 'test_indeterminate(true)'}}
constexpr int run_test_indeterminate2 = test_indeterminate(true);
struct ref_mem {
const int &rm;
};
constexpr int global_int = 0;
// expected-error@+2 {{constexpr variable 'run_ref_mem' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a type with a reference member is not allowed in a constant expression}}
constexpr unsigned long run_ref_mem = __builtin_bit_cast(
unsigned long, ref_mem{global_int});
union u {
int im;
};
// expected-error@+2 {{constexpr variable 'run_u' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a union type is not allowed in a constant expression}}
constexpr int run_u = __builtin_bit_cast(int, u{32});
struct vol_mem {
volatile int x;
};
// expected-error@+2 {{constexpr variable 'run_vol_mem' must be initialized by a constant expression}}
// expected-note@+1 {{non-literal type 'vol_mem' cannot be used in a constant expression}}
constexpr int run_vol_mem = __builtin_bit_cast(int, vol_mem{43});
struct mem_ptr {
int vol_mem::*x; // expected-note{{invalid type 'int vol_mem::*' is a member of 'mem_ptr'}}
};
// expected-error@+2 {{constexpr variable 'run_mem_ptr' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a member pointer type is not allowed in a constant expression}}
constexpr int run_mem_ptr = __builtin_bit_cast(unsigned long, mem_ptr{nullptr});
struct A { char c; /* char padding : 8; */ short s; };
struct B { unsigned char x[4]; };
constexpr B one() {
A a = {1, 2};
return bit_cast<B>(a);
}
constexpr char good_one = one().x[0] + one().x[2] + one().x[3];
// expected-error@+2 {{constexpr variable 'bad_one' must be initialized by a constant expression}}
// expected-note@+1 {{read of uninitialized object is not allowed in a constant expression}}
constexpr char bad_one = one().x[1];
constexpr A two() {
B b = one(); // b.x[1] is indeterminate.
b.x[0] = 'a';
b.x[2] = 1;
b.x[3] = 2;
return bit_cast<A>(b);
}
constexpr short good_two = two().c + two().s;
namespace std {
enum byte : unsigned char {};
}
enum my_byte : unsigned char {};
struct pad {
char a;
int b;
};
constexpr int ok_byte = (__builtin_bit_cast(std::byte[8], pad{1, 2}), 0);
constexpr int ok_uchar = (__builtin_bit_cast(unsigned char[8], pad{1, 2}), 0);
#ifdef __CHAR_UNSIGNED__
// expected-note@+5 {{indeterminate value can only initialize an object of type 'unsigned char', 'char', or 'std::byte'; 'my_byte' is invalid}}}}
#else
// expected-note@+3 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'my_byte' is invalid}}
#endif
// expected-error@+1 {{constexpr variable 'bad_my_byte' must be initialized by a constant expression}}
constexpr int bad_my_byte = (__builtin_bit_cast(my_byte[8], pad{1, 2}), 0);
#ifndef __CHAR_UNSIGNED__
// expected-error@+3 {{constexpr variable 'bad_char' must be initialized by a constant expression}}
// expected-note@+2 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'char' is invalid}}
#endif
constexpr int bad_char = (__builtin_bit_cast(char[8], pad{1, 2}), 0);
struct pad_buffer { unsigned char data[sizeof(pad)]; };
constexpr bool test_pad_buffer() {
pad x = {1, 2};
pad_buffer y = __builtin_bit_cast(pad_buffer, x);
pad z = __builtin_bit_cast(pad, y);
return x.a == z.a && x.b == z.b;
}
static_assert(test_pad_buffer());
constexpr unsigned char identity1a = 42;
constexpr unsigned char identity1b = __builtin_bit_cast(unsigned char, identity1a);
static_assert(identity1b == 42);
struct IdentityInStruct {
unsigned char n;
};
constexpr IdentityInStruct identity2a = {42};
constexpr unsigned char identity2b = __builtin_bit_cast(unsigned char, identity2a.n);
union IdentityInUnion {
unsigned char n;
};
constexpr IdentityInUnion identity3a = {42};
constexpr unsigned char identity3b = __builtin_bit_cast(unsigned char, identity3a.n);
namespace test_bool {
constexpr bool test_bad_bool = bit_cast<bool>('A'); // expected-error {{must be initialized by a constant expression}} expected-note{{in call}}
static_assert(round_trip<signed char>(true), "");
static_assert(round_trip<unsigned char>(false), "");
static_assert(round_trip<bool>(false), "");
static_assert(round_trip<bool>((char)0), "");
static_assert(round_trip<bool>((char)1), "");
}
namespace test_long_double {
#ifdef __x86_64
constexpr __int128_t test_cast_to_int128 = bit_cast<__int128_t>((long double)0); // expected-error{{must be initialized by a constant expression}} expected-note{{in call}}
constexpr long double ld = 3.1425926539;
struct bytes {
unsigned char d[16];
};
static_assert(round_trip<bytes>(ld), "");
static_assert(round_trip<long double>(10.0L));
constexpr bool f(bool read_uninit) {
bytes b = bit_cast<bytes>(ld);
unsigned char ld_bytes[10] = {
0x0, 0x48, 0x9f, 0x49, 0xf0,
0x3c, 0x20, 0xc9, 0x0, 0x40,
};
for (int i = 0; i != 10; ++i)
if (ld_bytes[i] != b.d[i])
return false;
if (read_uninit && b.d[10]) // expected-note{{read of uninitialized object is not allowed in a constant expression}}
return false;
return true;
}
static_assert(f(/*read_uninit=*/false), "");
static_assert(f(/*read_uninit=*/true), ""); // expected-error{{static assertion expression is not an integral constant expression}} expected-note{{in call to 'f(true)'}}
constexpr bytes ld539 = {
0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0xc0, 0x86,
0x8, 0x40, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0,
};
constexpr long double fivehundredandthirtynine = 539.0;
static_assert(bit_cast<long double>(ld539) == fivehundredandthirtynine, "");
#else
static_assert(round_trip<__int128_t>(34.0L));
#endif
}
namespace test_vector {
typedef unsigned uint2 __attribute__((vector_size(2 * sizeof(unsigned))));
typedef char byte8 __attribute__((vector_size(sizeof(unsigned long long))));
constexpr uint2 test_vector = { 0x0C05FEFE, 0xCAFEBABE };
static_assert(bit_cast<unsigned long long>(test_vector) == (LITTLE_END
? 0xCAFEBABE0C05FEFE
: 0x0C05FEFECAFEBABE), "");
static_assert(round_trip<uint2>(0xCAFEBABE0C05FEFEULL), "");
static_assert(round_trip<byte8>(0xCAFEBABE0C05FEFEULL), "");
typedef bool bool8 __attribute__((ext_vector_type(8)));
typedef bool bool9 __attribute__((ext_vector_type(9)));
typedef bool bool16 __attribute__((ext_vector_type(16)));
typedef bool bool17 __attribute__((ext_vector_type(17)));
typedef bool bool32 __attribute__((ext_vector_type(32)));
typedef bool bool128 __attribute__((ext_vector_type(128)));
static_assert(bit_cast<unsigned char>(bool8{1,0,1,0,1,0,1,0}) == (LITTLE_END ? 0x55 : 0xAA), "");
static_assert(round_trip<bool8>(static_cast<unsigned char>(0)), "");
static_assert(round_trip<bool8>(static_cast<unsigned char>(1)), "");
static_assert(round_trip<bool8>(static_cast<unsigned char>(0x55)), "");
static_assert(bit_cast<unsigned short>(bool16{1,1,1,1,1,0,0,0, 1,1,1,1,0,1,0,0}) == (LITTLE_END ? 0x2F1F : 0xF8F4), "");
static_assert(round_trip<bool16>(static_cast<short>(0xCAFE)), "");
static_assert(round_trip<bool32>(static_cast<int>(0xCAFEBABE)), "");
static_assert(round_trip<bool128>(static_cast<__int128_t>(0xCAFEBABE0C05FEFEULL)), "");
// expected-error@+2 {{constexpr variable 'bad_bool9_to_short' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast involving type 'bool __attribute__((ext_vector_type(9)))' (vector of 9 'bool' values) is not allowed in a constant expression; element size 1 * element count 9 is not a multiple of the byte size 8}}
constexpr unsigned short bad_bool9_to_short = __builtin_bit_cast(unsigned short, bool9{1,1,0,1,0,1,0,1,0});
// expected-error@+2 {{constexpr variable 'bad_short_to_bool9' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast involving type 'bool __attribute__((ext_vector_type(9)))' (vector of 9 'bool' values) is not allowed in a constant expression; element size 1 * element count 9 is not a multiple of the byte size 8}}
constexpr bool9 bad_short_to_bool9 = __builtin_bit_cast(bool9, static_cast<unsigned short>(0));
// expected-error@+2 {{constexpr variable 'bad_int_to_bool17' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast involving type 'bool __attribute__((ext_vector_type(17)))' (vector of 17 'bool' values) is not allowed in a constant expression; element size 1 * element count 17 is not a multiple of the byte size 8}}
constexpr bool17 bad_int_to_bool17 = __builtin_bit_cast(bool17, 0x0001CAFEU);
}
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