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Make is_default_constructible work for spans.

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Casey Carter 2017-01-28 00:08:48 -08:00 committed by Neil MacIntosh
parent f93d325495
commit 96eaf274f8
2 changed files with 20 additions and 9 deletions
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4
gsl/span
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@ -359,6 +359,10 @@ public:
constexpr static const index_type extent = Extent; constexpr static const index_type extent = Extent;
// [span.cons], span constructors, copy, assignment, and destructor // [span.cons], span constructors, copy, assignment, and destructor
template <bool Dependent = false,
// "Dependent" is needed to make "std::enable_if_t<Dependent || Extent <= 0>" SFINAE,
// since "std::enable_if_t<Extent <= 0>" is ill-formed when Extent is greater than 0.
class = std::enable_if_t<(Dependent || Extent <= 0)>>
constexpr span() noexcept : storage_(nullptr, details::extent_type<0>()) {} constexpr span() noexcept : storage_(nullptr, details::extent_type<0>()) {}
constexpr span(std::nullptr_t) noexcept : span() {} constexpr span(std::nullptr_t) noexcept : span() {}

7
tests/span_tests.cpp
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@ -1557,6 +1557,13 @@ SUITE(span_tests)
span<int> s{arr}; span<int> s{arr};
CHECK(at(s,0) == 1 && at(s,1) == 2); CHECK(at(s,0) == 1 && at(s,1) == 2);
} }
TEST(default_constructible)
{
CHECK((std::is_default_constructible<span<int>>::value));
CHECK((std::is_default_constructible<span<int, 0>>::value));
CHECK((!std::is_default_constructible<span<int, 42>>::value));
}
} }
int main(int, const char* []) { return UnitTest::RunAllTests(); } int main(int, const char* []) { return UnitTest::RunAllTests(); }