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Update PR for 4383.
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‎xml/issue4383.xml‎

Lines changed: 87 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -77,61 +77,61 @@ struct <i>cw-operators</i> {
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// <i>pseudo-mutators</i>
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template&lt;<i>constexpr-param</i> T&gt;
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constexpr auto operator++(this T) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>++x<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;++x&gt;(); }
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{ return constant_wrapper&lt;[] { auto c = T::value; return ++c; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T&gt;
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constexpr auto operator++(this T, int) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x++<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x++&gt;(); }
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{ return constant_wrapper&lt;[] { auto c = T::value; return c++; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T&gt;
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constexpr auto operator--(this T) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>--x<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;--x&gt;(); }
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{ return constant_wrapper&lt;[] { auto c = T::value; return --c; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T&gt;
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constexpr auto operator--(this T, int) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x--<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x--&gt;(); }
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{ return constant_wrapper&lt;[] { auto c = T::value; return c--; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator+=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x += R::value<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x += R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v += R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator-=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x -= R::value<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x -= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v -= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator*=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x *= R::value<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x *= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v *= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator/=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x /= R::value<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x /= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v /= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator%=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x %= R::value<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x %= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v %= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator&amp;=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x &amp;= R::value<ins>&gt;()</ins>; }
118+
requires requires(T::value_type x) { constant_wrapper&lt;x &amp;= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v &amp;= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
121121
constexpr auto operator|=(this T, R) noexcept
122-
requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x |= R::value<ins>&gt;()</ins>; }
122+
requires requires(T::value_type x) { constant_wrapper&lt;x |= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v |= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator^=(this T, R) noexcept
126-
requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x ^= R::value<ins>&gt;()</ins>; }
126+
requires requires(T::value_type x) { constant_wrapper&lt;x ^= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v ^= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
129129
constexpr auto operator&lt;&lt;=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x &lt;&lt;= R::value<ins>&gt;()</ins>; }
130+
requires requires(T::value_type x) { constant_wrapper&lt;x &lt;&lt;= R::value&gt;(); }
131131
{ return constant_wrapper&lt;[] { auto v = T::value; return v &lt;&lt;= R::value; }()&gt;{}; }
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template&lt;<i>constexpr-param</i> T, <i>constexpr-param</i> R&gt;
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constexpr auto operator&gt;&gt;=(this T, R) noexcept
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requires requires(T::value_type x) { <ins>constant_wrapper&lt;</ins>x &gt;&gt;= R::value<ins>&gt;()</ins>; }
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requires requires(T::value_type x) { constant_wrapper&lt;x &gt;&gt;= R::value&gt;(); }
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{ return constant_wrapper&lt;[] { auto v = T::value; return v &gt;&gt;= R::value; }()&gt;{}; }
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};
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</pre>
@@ -142,7 +142,79 @@ struct <i>cw-operators</i> {
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</ol>
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</superseded>
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145-
<note>2025-11-04; Zach provides improved wording</note>
145+
<p>
146+
This wording is relative to <paper num="N5014"/>.
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</p>
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<ol>
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<li><p>Modify <sref ref="[const.wrap.class]"/>, class template <tt>constant_wrapper</tt> synopsis, as indicated:</p>
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<blockquote class="note">
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<p>
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[<i>Drafting note:</i> The requires clause follows the form of `constant_wrapper`'s
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function call operator.]
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</p>
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</blockquote>
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<blockquote>
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<pre>
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struct <i>cw-operators</i> { // <i>exposition only</i>
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[&hellip;]
164+
// <i>pseudo-mutators</i>
165+
template&lt;<i>constexpr-param</i> T&gt;
166+
constexpr auto operator++(this T) noexcept -&gt; constant_wrapper&lt;++Y&gt; { return {}; }
167+
template&lt;<i>constexpr-param</i> T&gt;
168+
constexpr auto operator++(this T, int) noexcept -&gt; constant_wrapper&lt;Y++&gt; { return {}; }
169+
template&lt;<i>constexpr-param</i> T&gt;
170+
constexpr auto operator--(this T) noexcept -&gt; constant_wrapper&lt;--Y&gt; { return {}; }
171+
template&lt;<i>constexpr-param</i> T&gt;
172+
constexpr auto operator--(this T, int) noexcept -&gt; constant_wrapper&lt;Y--&gt; { return {}; }
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174+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
175+
friend constexpr auto operator+=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value += V::value)&gt; { return {}; }
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template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
177+
friend constexpr auto operator-=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value -= V::value)&gt; { return {}; }
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template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
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friend constexpr auto operator*=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value *= V::value)&gt; { return {}; }
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template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
181+
friend constexpr auto operator/=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value /= V::value)&gt; { return {}; }
182+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
183+
friend constexpr auto operator%=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value %= V::value)&gt; { return {}; }
184+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
185+
friend constexpr auto operator&amp;=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value &amp;= V::value)&gt; { return {}; }
186+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
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friend constexpr auto operator|=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value |= V::value)&gt; { return {}; }
188+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
189+
friend constexpr auto operator^=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value ^= V::value)&gt; { return {}; }
190+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
191+
friend constexpr auto operator&lt;&lt;=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value &lt;&lt;= V::value)&gt; { return {}; }
192+
template&lt;<i>constexpr-param</i> U, <i>constexpr-param</i> V&gt;
193+
friend constexpr auto operator&gt;&gt;=(U, V) noexcept -&gt; constant_wrapper&lt;(U::value &gt;&gt;= V::value)&gt; { return {}; }
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};
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}
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197+
template&lt;exposition_only::cw_fixed_value X, typename&gt;
198+
struct constant_wrapper: exposition_only::cw_operators {
199+
static constexpr const auto &amp; value = X.data;
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using type = constant_wrapper;
201+
using value_type = typename decltype(X)::type;
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<del>template&lt;<i>constexpr-param</i> R&gt;
204+
constexpr auto operator=(R) const noexcept requires requires(value_type x) { x = R::value; }
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{ return constant_wrapper&lt;[] { auto v = value; return v = R::value; }()&gt;{}; }</del>
206+
<ins>template&lt;<i>constexpr-param</i> R&gt;
207+
constexpr auto operator=(R) const noexcept -&gt; constant_wrapper&lt;X = R::value&gt; { return {}; }</ins>
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constexpr operator decltype(auto)() const noexcept { return value; }
210+
};
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</pre>
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</blockquote>
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</li>
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</ol>
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</discussion>
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