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Making overload_t's copy constructor have priority #413

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016f0c0
Making overload_t's copy constructor have priority
DarthRubik Jul 1, 2018
784fa22
Fixing trailing white space....
DarthRubik Jul 3, 2018
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6 changes: 5 additions & 1 deletion include/boost/hana/functional/overload.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ Distributed under the Boost Software License, Version 1.0.

#include <boost/hana/config.hpp>
#include <boost/hana/detail/decay.hpp>
#include <type_traits>


BOOST_HANA_NAMESPACE_BEGIN
Expand Down Expand Up @@ -47,7 +48,10 @@ BOOST_HANA_NAMESPACE_BEGIN
using overload_t<F>::type::operator();
using overload_t<G...>::type::operator();

template <typename F_, typename ...G_>
template <typename F_, typename ...G_,
typename = std::enable_if_t<
!std::is_same<overload_t,std::decay_t<F_>>::value
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@ldionne ldionne Jul 18, 2018

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Nitpick: Please add a space between overload_t and std::decay_t<F_>.

>>
constexpr explicit overload_t(F_&& f, G_&& ...g)
: overload_t<F>::type(static_cast<F_&&>(f))
, overload_t<G...>::type(static_cast<G_&&>(g)...)
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17 changes: 17 additions & 0 deletions test/issues/github_412.cpp
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@@ -0,0 +1,17 @@
#include "boost/hana.hpp"
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@ldionne ldionne Jul 18, 2018

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We use <> to include Hana's headers in the tests. Also, we try to include the most specific header. #include <boost/hana/functional/overload.hpp>


constexpr int f() { return 12; }
constexpr int g(int) { return 42; }



// This test makes sure that overload can
// be copy constructed
int main() {
auto a = boost::hana::overload(f,g);
auto b(a);


BOOST_HANA_RUNTIME_CHECK(b() == 12);
BOOST_HANA_RUNTIME_CHECK(b(1) == 42);
}