https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122899
Bug ID: 122899
Summary: constexpr error with self-referencing struct
Product: gcc
Version: 15.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
This program
```
template <class T> class Foo {
T t;
const T* t_ptr;
public:
constexpr Foo(T t): t(t), t_ptr(&this->t) {}
constexpr Foo(const Foo& foo): t(foo.t), t_ptr(&this->t) {}
constexpr T get_t() const {
return *t_ptr;
}
};
template <class T> constexpr Foo<T> foo(T t) {
return Foo<T>(t);
}
constexpr auto f = foo(1);
static_assert(f.get_t() == 1);
```
is accepted by Clang, EDG and MSVC. But GCC complains:
```
<source>:16:25: error: non-constant condition for static assertion
16 | static_assert(f.get_t() == 1);
| ~~~~~~~~~~^~~~
<source>:16:22: in 'constexpr' expansion of 'f.Foo<int>::get_t()'
<source>:8:17: error: the value of 'f' is not usable in a constant expression
8 | return *t_ptr;
| ^~~~~
<source>:15:16: note: 'f' used in its own initializer
15 | constexpr auto f = foo(1);
|
```
Online demo: https://gcc.godbolt.org/z/hha5ceqb1
Original report: https://stackoverflow.com/q/79831573/7325599
