Compile with -O2 and you will see that it prints 0

Em sáb., 26 de jul. de 2025, 21:49, Frederick Virchanza Gotham via
Std-Proposals <std-proposals_at_[hidden]> escreveu:

> On Sat, Jul 26, 2025 at 10:54 PM Jonathan Wakely wrote:
> >
> > Any value written to a non-static data member by the destructor is a
> > dead store, it cannot be read after the destructor finishes. It is
> irrelevant
> > whether the object was initialized using placement new.
> >
> > As it's a dead store, the compiler can remove that store completely.
>
>
> Are you saying that the following program has undefined behaviour or
> that it's not guaranteed to print "deadbeef"?
>
> https://godbolt.org/z/6bcnz95Ed
>
> Specifically, are you saying that after the MyClass destructor has
> returned, that the first 8 bytes of 'buf' cannot be perused?
>
> And here it is copy-pasted:
>
> char unsigned buf[64u];
>
> struct MyClass {
> int *p = new int;
> ~MyClass(void)
> {
> delete p;
> p = (int*)(void*)0xdeadbeef;
> }
> };
>
> #include <iostream>
> #include <iomanip>
> using std::cout, std::hex, std::endl;
>
> int main(void)
> {
> MyClass *const ptr =
> static_cast<MyClass*>(static_cast<void*>(&buf));
> ::new(ptr) MyClass;
> ptr->~MyClass();
> // The loop on the next line is for Little Endian CPU's
> for ( unsigned i = 3u; i <= 3u; --i ) cout << hex <<
> (unsigned)buf[i];
> cout << endl;
> }
> --
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