| Issue |
135601
|
| Summary |
"uninitialized when used here" warning in successful constant _expression_ evaluation
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Fedr
|
This program:
```
#include <memory>
struct A {
int i, j;
constexpr A() : i((std::construct_at(&j, 2), j-1)) {}
};
constexpr A a{};
static_assert(a.i == 1);
static_assert(a.j == 2);
```
is accepted in GCC and MSVC.
Clang also accepts it with the warning:
```
<source>:5:50: warning: field 'j' is uninitialized when used here [-Wuninitialized]
5 | constexpr A() : i((std::construct_at(&j, 2), j-1)) {}
| ^
```
Online demo: https://gcc.godbolt.org/z/YzEoPPj96
This looks contradicting, since reading of uninitialized values in constant expressions must result in hard fail. Or the program is ok, and the diagnostic is simply wrong.
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