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From: "daniel.kruegler at googlemail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/94554] spurious -Waddress warning within "if constexpr" function-null compares
Date: Tue, 14 Apr 2020 21:56:27 +0000 [thread overview]
Message-ID: <bug-94554-4-aDiKFWI6yj@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-94554-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94554
--- Comment #3 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Melissa from comment #0)
> Clang errors on this case, so it's possible that my code is invalid: Is it
> legal to compare a function pointer against null in a constant-expression?
The example is ill-formed because the condition of 'if constexpr' is more
restricted than that of normal 'if': It expects "a contextually converted
constant expression of type bool" and [expr.const] p10 lists the allowed
conversions in this case. This list omits the boolean conversions
([conv.bool]).
But the example would become valid when rewritten as follows:
int meow() { return 1; }
void kitty(int);
template <int (*F)()>
void test() {
if constexpr (bool(F)) {
kitty(F());
} else {
kitty(2);
}
}
template void test<nullptr>();
template void test<meow>();
next prev parent reply other threads:[~2020-04-14 21:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-10 18:58 [Bug c++/94554] New: " myriachan at gmail dot com
2020-04-10 20:20 ` [Bug c++/94554] " mpolacek at gcc dot gnu.org
2020-04-10 20:22 ` myriachan at gmail dot com
2020-04-14 21:56 ` daniel.kruegler at googlemail dot com [this message]
2020-07-10 15:13 ` lts-rudolph at gmx dot de
2020-10-01 17:54 ` mail at 3v1n0 dot net
2022-06-23 4:25 ` jason at gcc dot gnu.org
2022-06-23 4:31 ` jason at gcc dot gnu.org
2022-06-23 15:08 ` cvs-commit at gcc dot gnu.org
2022-06-23 15:44 ` jason at gcc dot gnu.org
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