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From: "harald at gigawatt dot nl" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/115222] gcc ignores noexcept on fields' deconstructors in
 an union
Date: Sat, 25 May 2024 12:44:06 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115222

Harald van Dijk <harald at gigawatt dot nl> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |harald at gigawatt dot nl

--- Comment #5 from Harald van Dijk <harald at gigawatt dot nl> ---
I end up with a different reduced test case that does not involve unions:

template <typename _Tp> _Tp declval() noexcept;

template <typename _Tp>
inline constexpr bool is_nothrow_destructible_v =3D noexcept(declval<_Tp>()=
);

struct A { ~A() noexcept(false) =3D delete; };
struct B : A { ~B(); };
static_assert(is_nothrow_destructible_v<B>);

The assertion passes in GCC, fails in clang, but I think clang is right her=
e.
It looks like GCC ignores the deleted destructor for determining whether B's
destructor should be implicitly noexcept, but the wording that Andrew Pinski
referenced in comment #2 says B's destructor is potentially throwing "if an=
y of
the destructors for any of its potentially constructed subobjects has a
potentially-throwing exception specification" without regard to whether tho=
se
destructors are deleted.=