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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/98216] [C++20] std::array<double, N> template parameter error with negative values Date: Thu, 10 Dec 2020 17:05:07 +0000 [thread overview] Message-ID: <bug-98216-4-uFNzSZkJT3@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-98216-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98216 --- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- Reduced: template<typename T, int N> struct array { constexpr T& operator[](int n) { return d[n]; } constexpr const T& operator[](int n) const { return d[n]; } constexpr bool operator==(const array& a) const { for (int i = 0; i < N; ++i) if (d[i] != a.d[i]) return false; return true; } T d[N]; }; using an_array = array <double, 1>; constexpr auto add_array (an_array a, an_array const& b) { a[0] += b[0]; return a; } template <an_array A> struct wrapper { static constexpr auto arr = A; }; template <an_array A1 , an_array A2> auto add (wrapper <A1> const&, wrapper <A2> const&) { return wrapper <add_array (A1, A2)> {}; } constexpr auto ONE = an_array {{ 1. }}; constexpr auto MINUS_ONE = an_array {{ -1. }}; constexpr auto MINUS_TWO = an_array {{ -2. }}; int main () { auto a = wrapper <MINUS_TWO> {}; auto b = wrapper <ONE> {}; auto c = add (a, b); __builtin_printf("%f %f %f\n", a.arr[0], b.arr[0], c.arr[0]); if (c.arr != MINUS_ONE) __builtin_abort(); } Prints: -2.000000 1.000000 -2.000000 Aborted (core dumped)
next prev parent reply other threads:[~2020-12-10 17:05 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-09 15:43 [Bug c++/98216] New: " emmanuel.le-trong@cnrs-orleans.fr 2020-12-09 16:04 ` [Bug c++/98216] " redi at gcc dot gnu.org 2020-12-10 7:33 ` rguenth at gcc dot gnu.org 2020-12-10 17:05 ` redi at gcc dot gnu.org [this message] 2020-12-10 17:16 ` redi at gcc dot gnu.org 2020-12-10 17:56 ` emmanuel.le-trong@cnrs-orleans.fr 2020-12-14 20:56 ` ppalka at gcc dot gnu.org 2021-07-27 8:08 ` [Bug c++/98216] [C++20] template mangling for double template argument is wrong pinskia at gcc dot gnu.org 2021-09-23 18:57 ` ppalka at gcc dot gnu.org 2021-09-23 19:01 ` ppalka at gcc dot gnu.org 2021-09-24 16:36 ` cvs-commit at gcc dot gnu.org 2021-09-24 19:36 ` emmanuel.le-trong@cnrs-orleans.fr 2021-10-06 14:15 ` cvs-commit at gcc dot gnu.org 2021-10-14 19:06 ` hq.ks at web dot de 2021-10-14 21:39 ` pinskia at gcc dot gnu.org
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