Viewing file:  bit-cast14.C (1.67 KB) -rw-r--r--
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// P1272R4
// { dg-do compile { target c++14 } }
struct S { unsigned char a : 8, b : 5, c : 3, d, e; unsigned int f : 8, g : 24; };
struct T1 { unsigned char a : 1, : 7, b : 5, c : 3, d, e; unsigned int f : 8, g : 24; };
struct T2 { unsigned char a : 8, b : 1, : 4, c : 3, d, e; unsigned int f : 8, g : 24; };
struct T3 { unsigned char a : 8, b : 5, c : 1, : 2, d, e; unsigned int f : 8, g : 24; };
struct T4 { unsigned char a : 8, b : 5, c : 3, d, e; unsigned int f : 1, : 7, g : 24; };
constexpr bool
f1 ()
{
T1 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
return true;
}
constexpr bool
f2 ()
{
T2 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
return true;
}
constexpr bool
f3 ()
{
T3 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
return true;
}
constexpr bool
f4 ()
{
T4 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t); // { dg-error "accessing uninitialized byte" }
return true;
}
constexpr bool
f5 ()
{
T1 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
unsigned char a = s.a;
return true;
}
constexpr bool
f6 ()
{
T2 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
unsigned char b = s.b;
return true;
}
constexpr bool
f7 ()
{
T3 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
unsigned char c = s.c;
return true;
}
constexpr bool a = f1 ();
constexpr bool b = f2 ();
constexpr bool c = f3 ();
constexpr bool d = f4 ();
constexpr bool e = f5 (); // { dg-error "accessing uninitialized member" }
constexpr bool f = f6 (); // { dg-error "accessing uninitialized member" }
constexpr bool g = f7 (); // { dg-error "accessing uninitialized member" }
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