https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119561
Bug ID: 119561
Summary: GCC hasn't completely forbidden user-declared
specializations of std::initializer_list
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Keywords: accepts-invalid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: de34 at live dot cn
Target Milestone: ---
Per [initializer.list.syn]/2 (https://eel.is/c++draft/initializer.list.syn#2)
(added via LWG 2129 (https://cplusplus.github.io/LWG/issue2129)), the following
code snippet is ill-formed (neither UB nor IFNDR) and thus should be rejected.
(Although this is an LWG issue, compiler change is necessary.)
```
#include <initializer_list>
template<class T>
class std::initializer_list<T*> {
private:
void* m_array_;
decltype(sizeof(0)) m_len_;
};
```
But currently GCC (/w libstdc++) silently accepts it
(https://godbolt.org/z/q6TMo91Ef).
GCC should either directly detect such specializations (like MSVC and EDG) or
provide some more general mechanism like Clang's [[clang::no_specializations]].
