libstdc++: Make std::common_iterator completely constexpr-able (LWG 3574)
This library issue was approved in the October 2021 plenary. libstdc++-v3/ChangeLog: * include/bits/stl_iterator.h (common_iterator): Add constexpr to all member functions (LWG 3574). * testsuite/24_iterators/common_iterator/1.cc: Evaluate some tests as constant expressions. * testsuite/24_iterators/common_iterator/2.cc: Likewise.
This commit is contained in:
Jonathan Wakely
parent
accccf7dee
commit
11d3e8f436
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@ -77,11 +77,12 @@
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# define __cpp_lib_array_constexpr 201803L
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#endif
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#if __cplusplus > 201703L
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#if __cplusplus >= 202002L
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# include <compare>
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# include <new>
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# include <bits/exception_defines.h>
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# include <bits/iterator_concepts.h>
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# include <bits/stl_construct.h>
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#endif
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namespace std _GLIBCXX_VISIBILITY(default)
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@ -1938,7 +1939,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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}
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common_iterator&
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constexpr common_iterator&
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operator=(const common_iterator& __x)
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noexcept(is_nothrow_copy_assignable_v<_It>
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&& is_nothrow_copy_assignable_v<_Sent>
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@ -1953,7 +1954,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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&& convertible_to<const _Sent2&, _Sent>
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&& assignable_from<_It&, const _It2&>
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&& assignable_from<_Sent&, const _Sent2&>
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common_iterator&
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constexpr common_iterator&
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operator=(const common_iterator<_It2, _Sent2>& __x)
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noexcept(is_nothrow_constructible_v<_It, const _It2&>
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&& is_nothrow_constructible_v<_Sent, const _Sent2&>
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@ -1973,7 +1974,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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_M_index = -1;
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[[fallthrough]];
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case 0b1001:
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::new((void*)std::__addressof(_M_sent)) _Sent(__x._M_sent);
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std::construct_at(std::__addressof(_M_sent), _Sent(__x._M_sent));
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_M_index = 1;
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break;
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case 0b0100:
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@ -1981,7 +1982,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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_M_index = -1;
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[[fallthrough]];
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case 0b1000:
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::new((void*)std::__addressof(_M_it)) _It(__x._M_it);
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std::construct_at(std::__addressof(_M_it), _It(__x._M_it));
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_M_index = 0;
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break;
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default:
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@ -1991,6 +1992,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return *this;
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}
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constexpr
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~common_iterator()
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{
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switch (_M_index)
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@ -2005,7 +2007,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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[[nodiscard]]
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decltype(auto)
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constexpr decltype(auto)
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operator*()
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{
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__glibcxx_assert(_M_index == 0);
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@ -2013,7 +2015,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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[[nodiscard]]
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decltype(auto)
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constexpr decltype(auto)
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operator*() const requires __detail::__dereferenceable<const _It>
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{
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__glibcxx_assert(_M_index == 0);
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@ -2021,7 +2023,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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[[nodiscard]]
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decltype(auto)
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constexpr decltype(auto)
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operator->() const requires __detail::__common_iter_has_arrow<_It>
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{
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__glibcxx_assert(_M_index == 0);
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@ -2036,7 +2038,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return __arrow_proxy{*_M_it};
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}
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common_iterator&
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constexpr common_iterator&
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operator++()
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{
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__glibcxx_assert(_M_index == 0);
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@ -2044,7 +2046,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return *this;
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}
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decltype(auto)
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constexpr decltype(auto)
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operator++(int)
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{
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__glibcxx_assert(_M_index == 0);
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@ -2066,7 +2068,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<typename _It2, sentinel_for<_It> _Sent2>
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requires sentinel_for<_Sent, _It2>
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friend bool
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friend constexpr bool
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operator== [[nodiscard]] (const common_iterator& __x,
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const common_iterator<_It2, _Sent2>& __y)
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{
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@ -2088,7 +2090,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<typename _It2, sentinel_for<_It> _Sent2>
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requires sentinel_for<_Sent, _It2> && equality_comparable_with<_It, _It2>
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friend bool
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friend constexpr bool
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operator== [[nodiscard]] (const common_iterator& __x,
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const common_iterator<_It2, _Sent2>& __y)
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{
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@ -2111,7 +2113,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<sized_sentinel_for<_It> _It2, sized_sentinel_for<_It> _Sent2>
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requires sized_sentinel_for<_Sent, _It2>
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friend iter_difference_t<_It2>
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friend constexpr iter_difference_t<_It2>
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operator- [[nodiscard]] (const common_iterator& __x,
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const common_iterator<_It2, _Sent2>& __y)
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{
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@ -2133,7 +2135,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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[[nodiscard]]
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friend iter_rvalue_reference_t<_It>
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friend constexpr iter_rvalue_reference_t<_It>
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iter_move(const common_iterator& __i)
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noexcept(noexcept(ranges::iter_move(std::declval<const _It&>())))
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requires input_iterator<_It>
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@ -2143,7 +2145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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template<indirectly_swappable<_It> _It2, typename _Sent2>
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friend void
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friend constexpr void
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iter_swap(const common_iterator& __x,
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const common_iterator<_It2, _Sent2>& __y)
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noexcept(noexcept(ranges::iter_swap(std::declval<const _It&>(),
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@ -2158,7 +2160,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<input_or_output_iterator _It2, sentinel_for<_It2> _Sent2>
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friend class common_iterator;
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bool _M_has_value() const noexcept { return _M_index < 2; }
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constexpr bool _M_has_value() const noexcept { return _M_index < 2; }
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union
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{
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@ -88,7 +88,7 @@ test02()
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VERIFY( i == (&i - out) );
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}
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void
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constexpr bool
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test03()
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{
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int arr[2] = { 1, 2 };
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@ -117,6 +117,9 @@ test03()
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VERIFY( (j - end) == -2 );
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VERIFY( (j - i) == 0 );
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if (std::is_constant_evaluated())
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return true;
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try
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{
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struct S { operator const int*() const { throw 1; } };
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@ -126,8 +129,12 @@ test03()
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catch (int)
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{
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}
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return true;
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}
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static_assert( test03() );
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void
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test04()
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{
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@ -32,18 +32,18 @@ struct iterator
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using difference_type = std::ptrdiff_t;
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using reference = value;
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value operator*() const { return value{counter}; }
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constexpr value operator*() const { return value{counter}; }
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iterator& operator++() { ++counter; return *this; }
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constexpr iterator& operator++() { ++counter; return *this; }
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iterator operator++(int) { auto i = *this; ++counter; return i; }
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constexpr iterator operator++(int) { auto i = *this; ++counter; return i; }
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bool operator==(sentinel s) const { return counter == s.limit; }
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constexpr bool operator==(sentinel s) const { return counter == s.limit; }
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int counter = 0;
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};
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void
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constexpr bool
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test01()
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{
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iterator i;
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@ -54,10 +54,12 @@ test01()
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VERIFY( begin->n == 1 );
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++begin;
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VERIFY( begin == end );
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return true;
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}
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int
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main()
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{
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test01();
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constexpr bool b1 = test01();
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}
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