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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/95832] std::vector<bool> specialization leading
 std::variant ctor treating it as int rather than bool
Date: Tue, 23 Jun 2020 15:36:35 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95832

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
No, that doesn't work for things convertible to pointers.

#include <variant>
struct P { operator void*() const; };
std::variant<bool> v{ P{} };

The argument type here is not a pointer, so your suggestion would construct=
 the
bool, which is exactly the case P0602 was designed to prevent.

"Can be converted to bool via conversion to a pointer or function pointer t=
ype"
is not practical to detect, and I have no intention of trying. See Bug 93628
for a related problem.=