[Issue 14033] runtime error about auto ptr = cast(T*)buf , T is class type
https://issues.dlang.org/show_bug.cgi?id=14033
--- Comment #3 from mzfh...@foxmail.com ---
i see,class and struct,their memory model is different,thanks.
struct stTest
{
int a;
int b;
void foo(){}
}
class clsTest
{
int a;
int b;
void foo(){}
}
void main()
{
int [100] buf ;
auto stPtr = cast(stTest*)buf;
stPtr.a = 123;//ok
stPtr.foo();//ok
auto clsPtr = cast(clsTest)buf;
clsPtr.a = 123;//ok
clsPtr.foo();//run time error,vfptr is not be assigned.
}
--
[Issue 14033] runtime error about auto ptr = cast(T*)buf , T is class type
https://issues.dlang.org/show_bug.cgi?id=14033 Steven Schveighoffer schvei...@yahoo.com changed: What|Removed |Added CC||schvei...@yahoo.com --- Comment #1 from Steven Schveighoffer schvei...@yahoo.com --- I think both should be a compile-time error. --
[Issue 14033] runtime error about auto ptr = cast(T*)buf , T is class type
https://issues.dlang.org/show_bug.cgi?id=14033 ag0ae...@gmail.com changed: What|Removed |Added Status|NEW |RESOLVED CC||ag0ae...@gmail.com Resolution|--- |INVALID --- Comment #2 from ag0ae...@gmail.com --- This is expected. `clsPtr.a` does two dereferences: 1) `clsPtr` is dereferenced and yields a `clsTest` object. Class objects are references (pointers) themselves. Since `buf` is all zeroes, you get a null Object. 2) To access the `a` field, that null reference is then dereferenced. Boom, segfault. In code: clsTest tmp = *clsPtr; /* tmp is null */ tmp.a = 123; /* dereferencing null */ Closing as invalid. --
