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detail::span_convertible handles void types #203

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12 changes: 10 additions & 2 deletions include/boost/core/span.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23,9 +23,17 @@ class span;

namespace detail {

template<class U, class T, class = void>
struct span_convertible
{
static constexpr bool value = false;
};

template<class U, class T>
struct span_convertible {
static constexpr bool value = std::is_convertible<U(*)[], T(*)[]>::value;
struct span_convertible<U, T, typename std::enable_if<
std::is_convertible<U(*)[], T(*)[]>::value>::type>
{
static constexpr bool value = true;
};

template<std::size_t E, std::size_t N>
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18 changes: 18 additions & 0 deletions test/span_constructible_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,20 @@ struct range {
}
};

struct buffer {
void* data() {
return 0;
}

const void* data() const {
return 0;
}

std::size_t size() const {
return 0;
}
};

struct base { };

struct derived
Expand Down Expand Up @@ -138,6 +152,10 @@ void test_range()
const range<int>&>));
BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<base>,
range<derived>&>));
BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<int>,
buffer>));
BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<int>,
const buffer&>));
}

void test_initializer_list()
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