https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117256
Bug ID: 117256
Summary: When initializing an object, padding bits are not set
to zero
Product: gcc
Version: 14.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: qurong at ios dot ac.cn
Target Milestone: ---
For this program:
```
#include <cstring>
#include <new>
#include <iostream>
struct A
{
char c;
int i;
};
int main()
{
char mem[sizeof(A)];
std::memset(mem, 1, sizeof(mem));
new(mem) A();
for (int i : mem)
std::cout << i << ", ";
return 0;
}
```
The 15th line ``new (mem) A();" should have performed value-initialization on
this A object. According to the rules of value-initialization, since the
default constructor of A is generated by the compiler, value-initialization
should first execute zero-initialization, which should set all padding bits to
zero. However, the output result shows that padding bits have not been set to
zero.
Compiler Explorer link: https://godbolt.org/z/TxPddcKzf
