https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67762
--- Comment #7 from Evgeniy Dushistov <dushistov at mail dot ru> ---
Here simple example extracted from Qt 6 git:
```
template<auto Signal=nullptr>
struct Prop {
void notify()
{
if constexpr (Signal != nullptr) {
}
}
};
class QObjectPrivate {
public:
struct ExtraData
{
inline void nameChangedForwarder() {}
};
};
int main()
{
Prop<&QObjectPrivate::ExtraData::nameChangedForwarder> prop;
prop.notify();
}
```
"g++ -std=c++17" compiles it just fine,
while "g++ -std=c++17 -fsanitize=undefined" gitves such error:
test2.cpp: In instantiation of 'void Prop<Signal>::notify() [with auto Signal =
&QObjectPrivate::ExtraData::nameChangedForwarder]':
test2.cpp:21:13: required from here
test2.cpp:5:34: error: '(QObjectPrivate::ExtraData::nameChangedForwarder != 0)'
is not a constant expression
5 | if constexpr (Signal != nullptr) {
| ~~~~~~~^~~~~~~~~~
This is with gcc 11.1.0
